Synthesis of novel vanadium alkylidyne complexes and their use in metathesis reactions
12522622 ยท 2026-01-13
Assignee
Inventors
Cpc classification
C07F9/00
CHEMISTRY; METALLURGY
B01J31/12
PERFORMING OPERATIONS; TRANSPORTING
International classification
Abstract
The subject invention provides a series of vanadium alkylidyne complexes with the metal center V being in high oxidation state, as well as novel methods for synthesizing these vanadium alkylidyne complexes using a vanadium oxo trialkoxyl complex as a starting material. The vanadium alkylidyne complexes of the subject invention can be used as catalysts for metathesis reactions.
Claims
1. A vanadium alkylidyne complex having a general formula of V(CR)X.sub.nL.sub.4-n, or a salt thereof, wherein n is 1, 2 or 3; X is an anionic ligand and each is independently selected from CH.sub.2SiMe.sub.3, a silane ligand, a siloxide ligand, a phenoxide ligand, an alkoxide ligand, an alkylthio ligand, an arylthiol ligand, a thioalkoxide ligand, a halide ligand, and an iminato ligand, or two X together form a bidentate ligand; L is a neutral ligand and each is independently selected from a pyridine ligand, a nitrile ligand, an ether ligand, a thioether ligand, a phosphine ligand, a N-heterocyclic carbene (NHC) ligand, and a cyclic(alkyl)(amino)carbene (CAAC) ligand, or two L together form a bidentate ligand; and R is alkyl, aryl or Si(R.sup.a).sub.3, wherein R.sup.a is selected from alkyl, substituted alkyl, aryl, and substituted aryl.
2. The vanadium alkylidyne complex of claim 1, having a general formula of: ##STR00039## wherein X.sub.1, X.sub.2, X.sub.5, X.sub.6, X.sub.7 and X.sub.8 are each independently selected from halogens, silyl, alkylthio, arylthiol, alkoxides, thioalkoxides, siloxides, iminato, phenoxides, NCO, NCS, and CH.sub.2SiMe.sub.3, or X.sub.1 and X.sub.2 together form a bidentate ligand, or two of X.sub.6, X.sub.7 and X.sub.8 together form a bidentate ligand; and L.sub.1, L.sub.2, L.sub.3, L.sub.4, L.sub.5 and L.sub.6 are each independently selected from phosphines, NHCs, pyridines, nitriles, ethers, thioethers, CAACs and substituted forms thereof, or L.sub.1 and L.sub.2 together form a bidentate ligand, or two of L.sub.3, L.sub.4, and L.sub.5 together form a bidentate ligand.
3. The vanadium alkylidyne complex of claim 2, wherein X.sub.1, X.sub.2, X.sub.5, X.sub.6, X.sub.7 and X.sub.8 are each independently selected from CH.sub.2SiMe.sub.3, OPh, SPh, OSiPh.sub.3, OSiMePh.sub.2, OSi(p-MeOC.sub.6H.sub.4).sub.3, OSiMe.sub.2Ph, o-MeOC.sub.6H.sub.4O, m-MeOC.sub.6H.sub.4O, p-MeOC.sub.6H.sub.4O, o-MeOC.sub.6H.sub.4S, m-MeOC.sub.6H.sub.4S, p-MeOC.sub.6H.sub.4S, 2,6-(MeO).sub.2C.sub.6H.sub.3O, 2,5-(MeO).sub.2C.sub.6H.sub.3O, 2,4-(MeO).sub.2C.sub.6H.sub.3O, 2,3-(MeO).sub.2C.sub.6H.sub.3O, 3,4-(MeO).sub.2C.sub.6H.sub.3O, 3,5-(MeO).sub.2C.sub.6H.sub.3O, OC(CF.sub.3).sub.3, OCPh(CF.sub.3).sub.2, OCMe(CF.sub.3).sub.2, OCMe.sub.2CF.sub.3, OCMe.sub.3, O-adamantyl (OAd), OBu.sup.1F.sub.6, OC.sub.6F.sub.5, I, F, Cl, Br, and ##STR00040##
4. The vanadium alkylidyne complex of claim 2, wherein L.sub.1, L.sub.2, L.sub.3, L.sub.4, L.sub.5 and L.sub.6 are each independently selected from PMe.sub.3, PEt.sub.3, NC.sub.5H.sub.5, NC.sub.5H.sub.4Br, NCCMe.sub.3, ##STR00041## or L.sub.1 and L.sub.2 together form a bipyridine ligand, or two of L.sub.3, L.sub.4, and L.sub.5 together form a bipyridine ligand.
5. The vanadium alkylidyne complex of claim 1, having a general formula of: ##STR00042## wherein each of X.sub.3 and X.sub.4 is independently selected from CH.sub.2SiMe.sub.3, OPh, SPh, OSiPh.sub.3, OSiMePh.sub.2, OSi(p-MeOC.sub.6H.sub.4).sub.3, OSiMe.sub.2Ph, o-MeOC.sub.6H.sub.4O, m-MeOC.sub.6H.sub.4O, p-MeOC.sub.6H.sub.4O, o-McOC.sub.6H.sub.4S, m-MeOC.sub.6H.sub.4S, p-MeOC.sub.6H.sub.4S, 2,6-(MeO).sub.2C.sub.6H.sub.3O, 2,5-(MeO).sub.2C.sub.6H.sub.3O, 2,4-(MeO).sub.2C.sub.6H.sub.3O, 2,3-(MeO).sub.2C.sub.6H.sub.3O, 3,4-(MeO).sub.2C.sub.6H.sub.3O, 3,5-(MeO).sub.2C.sub.6H.sub.3O, OC(CF.sub.3).sub.3, OCPh(CF.sub.3).sub.2, OCMe(CF.sub.3).sub.2, OCMe.sub.2CF.sub.3, OCMe.sub.3, OAd, OBu.sup.tF.sub.6, OC.sub.6F.sub.5, F, Cl, Br, and ##STR00043## or X.sub.3 and X.sub.4 together form a bidentate ligand.
6. The vanadium alkylidyne complex of claim 1, being ##STR00044## ##STR00045##
7. A composition comprising the vanadium alkylidyne complex, or a salt thereof, of claim 1.
Description
BRIEF DESCRIPTION OF DRAWINGS
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DETAILED DESCRIPTION OF THE INVENTION
(21) The subject invention provides catalytical compounds/complexes, and/or salts thereof, compositions comprising such compound/complex and/or salts thereof, synthesis of the compounds/complexes, and methods of using such compounds/complexes and/or salts thereof as catalysts in, for example, industrial processes producing chemicals employed in daily life, including plastics, advanced functional materials, household chemicals, agricultural compounds, pharmaceuticals, and many others.
(22) In certain embodiments, the subject invention provides catalytical compounds/complexes having a meter center of one of the Earth-abundant first-row metals, such as vanadium (V), titanium (Ti), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), and copper (Cu).
(23) The present invention provides a unique transformation involving anionic V(+5) alkylidene that converts a V(+5) oxo complex to a V(+5) alkylidyne in three steps without altering the oxidation state of the metal center. This method can be used to obtain rare 3d Schrock carbynes, which provide easy and scalable access to V(+5) alkylidynes. Those alkylidyne complexes can be utilized to mediate alkyne metathesis.
(24) Alkyne metathesis is a synthetic method for the synthesis of chemicals containing carbon-carbon triple bonds, including advanced materials that have potential applications in organic light-emitted diodes, organic photovoltaics, organic field-effect transistors, and optical and molecular sensors. The reversible nature of alkyne metathesis allows for the chemical recycling of resulting materials. In addition, alkynes are essential starting points for producing a large variety of organic compounds, taking advantage of the chemical versatility of a triple bond.
(25) Advantageously, the use of Earth-abundant first-row metal, such as vanadium, have an exceptionally broad impact on society by providing less expensive, greener, and energy-efficient alternatives. This, in turn, makes essential chemicals more accessible to consumers and decreases the human environmental footprint. Thus, first-row metal catalysts can offer a unique reactivity compared to second- and third-row counterparts.
(26) In certain embodiments, the subject invention provides a composition comprising a compound/complex having a metal center selected from first-row metals. In preferred embodiments, the composition of the subject invention further comprises a carrier, diluent, or excipient with which the compound/complex can be formulated or dissolved.
(27) In one embodiment, the subject invention provides a composition comprising the vanadium alkylidyne compound/complex of the subject invention. In one embodiment, the composition further comprises a carrier, diluent, or excipient with which the vanadium alkylidyne compound/complex can be formulated or dissolved. The carriers, diluents or excipients may include, for example, aqueous vehicles, non-aqueous vehicles, stabilizers, and solubility enhancers. In a specific embodiment, the carrier, diluent or excipient may be a solvent, e.g., an organic solvent such as toluene, pentane, or ether.
(28) In certain embodiments, the vanadium alkylidyne compound/complex of the subject invention is in a solid form or a liquid form when dissolved in a solvent. In specific embodiments, the solvent is selected from, for example, CDCl.sub.3, CD.sub.2Cl.sub.2, C.sub.6D.sub.6, toluene, C.sub.6H.sub.5F, THF, ether, DME, and pentane.
(29) In one embodiment, the subject invention provides a kit comprising the vanadium alkylidyne complex of the subject invention. The kit may further comprise a solvent, a container, and an instruction for use the vanadium alkylidyne complex.
(30) Vanadium Alkylidyne Complexes
(31) The subject invention provides a novel class of 3d Schrock carbyne, specifically a series of high oxidation state vanadium alkylidynes. In one embodiment, the present invention provides a vanadium alkylidyne complex having a general formula of V(CR)X.sub.nL.sub.4-n, wherein X is an anionic ligand; L is a neutral ligand; n is 1, 2 or 3; and R is alkyl, aryl or Si(R.sup.a).sub.3, wherein R.sup.a is selected from, for example, alkyl, substituted alkyl, aryl, and substituted aryl. In a specific embodiment, R is SiMe.sub.3.
(32) In certain embodiments, each X is independently selected from, for example, a silane based ligand, a siloxide based ligand, a phenoxide based ligand, an alkoxide based ligand, a thioalkoxide based ligand, a halide based ligand, and an iminato based ligand. In specific embodiments, each X is independently selected from, for example, halogens, alkoxides, thioalkoxides, siloxides, NCO, NCS, NO.sub.3, and pyrrolides.
(33) In certain embodiments, each L is independently selected from a pyridine based ligand, a nitrile based ligand, an ether based ligand, a thioether based ligand, a phosphine (such as trialkyl phosphine) based ligand, a saturated and unsaturated N-heterocyclic carbene (NHC) based ligand, and a cyclic(alkyl)(amino)carbene (CAAC) based ligand. In specific embodiments, each L is independently selected from, for example, phosphines, NHCs, pyridines, nitriles, ethers, thioethers, CAACs and substituted thereof.
(34) In certain embodiments, each of X and L can be a monodentate ligand, or two or three of X and L together form a bidentate ligand or a tridentate ligand.
(35) Generally, the nature of the alkylidyne group CR has a modest influence on the catalytic performance because it exchanges during the catalytic cycle. However, it is important for applications where the initiation step is crucial, such as ring-opening alkyne metathesis polymerization. In those cases, the right balance between the electronic and steric properties of the alkylidyne group is essential to ensure that the rate of initiation is higher than the rate of propagation to prevent undesired intra- and intermolecular chain-transfer processes and to obtain polymers with a narrow molecular weight distribution.
(36) By optimizing the ligand set around the Vanadium center, the vanadium alkylidynes provided by the present invention function as robust and reliable catalysts in, for example, alkyne cross-metathesis, ring-closing alkyne metathesis, ring-opening alkyne metathesis polymerization, and other related reactions.
(37) In one embodiment, the subject invention provides a vanadium alkylidyne complex having a structure of:
(38) ##STR00002## wherein L.sub.1 and L.sub.2 are neutral ligands; X.sub.1 and X.sub.2 are anionic ligands; and R is alkyl, aryl or Si(R.sup.a).sub.3, wherein R.sup.a is selected from, for example, alkyl, substituted alkyl, aryl, and substituted aryl. In a specific embodiment, R is SiMe.sub.3. In certain embodiments, each of X.sub.1, X.sub.2, L.sub.1 and L.sub.2 is a monodentate ligand, or two or three of X.sub.1, X.sub.2, L.sub.1 and L.sub.2 together form a bidentate ligand or a tridentate ligand.
(39) In a specific embodiment, one of X.sub.1, X.sub.2, L.sub.1 and L.sub.2 can be absent.
(40) In certain embodiments, each of X.sub.1 and X.sub.2 is independently selected from, for example, a silane based ligand, a siloxide based ligand, a phenoxide based ligand, an alkoxide based ligand, an alkylthio based ligand, an arylthiol based ligand, a thioalkoxide based ligand, a halide based ligand, and an iminato based ligand. In certain embodiments, X.sub.1 and X.sub.2 are each independently selected from, for example, halogens, alkoxides, silyl, alkylthio, arylthiol, thioalkoxides, siloxides, NCO, NCS, NO.sub.3, and pyrrolides.
(41) In preferred embodiments, X.sub.1 and X.sub.2 are each independently selected from, for example, CH.sub.2SiMe.sub.3, OPh, SPh, OSiPh.sub.3, OSiMePh.sub.2, OSi(p-MeOC.sub.6H.sub.4).sub.3, OSiMe.sub.2Ph, o-MeOC.sub.6H.sub.4O, m-MeOC.sub.6H.sub.4O, p-MeOC.sub.6H.sub.4O, o-MeOC.sub.6H.sub.4S, m-MeOC.sub.6H.sub.4S, p-MeOC.sub.6H.sub.4S, 2,6-(MeO).sub.2C.sub.6H.sub.3O, 2,5-(MeO).sub.2C.sub.6H.sub.3O, 2,4-(MeO).sub.2C.sub.6H.sub.3O, 2,3-(MeO).sub.2C.sub.6H.sub.3O, 3,4-(MeO).sub.2C.sub.6H.sub.3O, 3,5-(MeO).sub.2C.sub.6H.sub.3O, OC(CF.sub.3).sub.3, OCPh(CF.sub.3).sub.2, OCMe(CF.sub.3).sub.2, OCMe.sub.2CF.sub.3, OCMe.sub.3, OAd, OBu.sup.tF.sub.6, OC.sub.6F.sub.5, OTf, pyrrolyl, I, F, Cl, Br, NO.sub.3, and
(42) ##STR00003##
(43) In specific embodiments, X.sub.1 and X.sub.2 together form a bidentate ligand, such as 1,1-bi-2-naphthol (BINOL) ligand.
(44) In certain embodiments, each of L.sub.1 and L.sub.2 is independently selected from, for example, a pyridine based ligand, a nitrile based ligand, an ether based ligand, a thioether based ligand, a phosphine (such as trialkyl phosphine) based ligand, a saturated and unsaturated N-heterocyclic carbene (NHC) based ligand, and a cyclic(alkyl)(amino)carbene (CAAC) based ligand. In preferred embodiments, L.sub.1 and L.sub.2 are each independently selected from, for example, phosphines, NHCs, pyridines, nitriles, ethers, thiocthers, CAACs and substituted thereof.
(45) In specific embodiments, L.sub.1 and L.sub.2 are each independently phosphines having a general structure of P(R.sub.1)(R.sub.2)(R.sub.3), where R.sub.1, R.sub.2, and R.sub.3 are each independently selected from hydrogen, alkyl, substituted alkyl, aryl and substituted aryl.
(46) In some embodiments, L.sub.1 and L.sub.2 are each independently NHCs, e.g., saturated or unsaturated NHCs. In a specific embodiment, the NHC is
(47) ##STR00004##
wherein R.sub.4, R.sub.5, R.sub.6, R.sub.7 and R.sub.8 are independently selected from hydrogen, alkyl, substituted alkyl, cycloalkyl, substituted cycloalkyl, aryl, and substituted aryl.
(48) In certain embodiments, L.sub.1 and L.sub.2 are each independently pyridines having a structure of
(49) ##STR00005##
wherein R.sub.6, R.sub.7, R.sub.8, R.sub.9, R.sub.10 are each independently selected from, for example, hydrogen, halogens, alkyl, substituted alkyl, hydorxyl, acyl, and NH.sub.2.
(50) In certain embodiments, L.sub.1 and L.sub.2 are each independently nitriles selected from, for example,
(51) ##STR00006##
wherein R.sub.6, R.sub.7, R.sub.8, R.sub.9, R.sub.10 are each independently selected from hydrogen, halogens, alkyl, substituted alkyl, alkoxides, aryl, substituted aryl, hydorxyl, acyl, and NH.sub.2.
(52) In a specific embodiment, each of L.sub.1 and L.sub.2 is independently selected from, for example, PMe.sub.3, PEt.sub.3, NC.sub.5H.sub.5, NC.sub.5H.sub.4Br, NCCMe.sub.3,
(53) ##STR00007##
(54) In one embodiment, the present invention provides a vanadium alkylidyne complex, which is a neutral complex containing two anionic ligands and two neutral ligands in addition to the VCR group, having a general formula of:
(55) ##STR00008## wherein each of X.sub.1 and X.sub.2 is an anionic ligand, and each of L.sub.1 and L.sub.2 is a neutral ligand. In a specific embodiment, one of X.sub.1, X.sub.2, L.sub.1 and L.sub.2 can be absent.
(56) In formula (I), each of X.sub.1, X.sub.2, L.sub.1 and L.sub.2 can be a monodentate ligand, or two or three of X.sub.1, X.sub.2, L.sub.1 and L.sub.2 together form a bidentate ligand or a tridentate ligand.
(57) In certain embodiments, each of X.sub.1 and X.sub.2 is independently selected from, for example, a silane based ligand, a siloxide based ligand, a phenoxide based ligand, an alkoxide based ligand, an alkylthio based ligand, an arylthiol based ligand, a thioalkoxide based ligand, a halide based ligand, and an iminato based ligand. In certain embodiments, X.sub.1 and X.sub.2 are each independently selected from, for example, halogens, silyl, alkylthio, arylthiol, alkoxides, thioalkoxides, siloxides, NCO, NCS, NO.sub.3, and pyrrolides.
(58) In preferred embodiments, X.sub.1 and X.sub.2 are each independently selected from, for example, CH.sub.2SiMe.sub.3, OPh, SPh, OSiPh.sub.3, OSiMePh.sub.2, OSi(p-MeOC.sub.6H.sub.4).sub.3, OSiMe.sub.2Ph, o-MeOC.sub.6H.sub.4O, m-MeOC.sub.6H.sub.4O, p-MeOC.sub.6H.sub.4O, o-MeOC.sub.6H.sub.4S, m-MeOC.sub.6H.sub.4S, p-MeOC.sub.6H.sub.4S, 2,6-(MeO).sub.2C.sub.6H.sub.3O, 2,5-(MeO).sub.2C.sub.6H.sub.3O, 2,4-(MeO).sub.2C.sub.6H.sub.3O, 2,3-(MeO).sub.2C.sub.6H.sub.3O, 3,4-(MeO).sub.2C.sub.6H.sub.3O, 3,5-(MeO).sub.2C.sub.6H.sub.3O, OC(CF.sub.3).sub.3, OCPh(CF.sub.3).sub.2, OCMe(CF.sub.3).sub.2, OCMe.sub.2CF.sub.3, OCMe.sub.3, OAd, OBu.sup.tF.sub.6, OC.sub.6F.sub.5, OTf, pyrrolyl, I, F, Cl, Br, NO.sub.3, and
(59) ##STR00009##
In certain embodiments, each of L.sub.1 and L.sub.2 is independently selected from a pyridine based ligand, a nitrile based ligand, an ether based ligand, a thioether based ligand, a phosphine (such as trialkyl phosphine) based ligand, a saturated and unsaturated N-heterocyclic carbene (NHC) based ligand, and a cyclic(alkyl)(amino)carbene (CAAC) based ligand. Preferably, each of L.sub.1 and L.sub.2 is independently selected from PMe.sub.3, PEt.sub.3, NC.sub.5H.sub.5, NC.sub.5H.sub.4Br, NCCMe.sub.3,
(60) ##STR00010##
(61) In certain embodiments, L.sub.1 and L.sub.2 together form a bidentate ligand selected from, for example, bipyridine ligands such as 4,4-bis(tert-butyl)-2,2-bipyridine (dtbbpy), and phenanthroline ligands.
(62) In some embodiments, the anionic ligand and the neutral ligand in the vanadium alkylidyne can be monodentate or polydentate (such as bidentate or tridentate) ligands. In certain embodiments, the vanadium alkylidyne provided by the subject invention contains substituted 2,2-bipyridine (dtbbpy) as a neutral ligand, wherein the dtbbpy ligand can be used to stabilize intermediates in the synthesis of the vanadium alkylidyne.
(63) In certain embodiments, the vanadium alkylidyne complex provided by the subject invention contains two identical neutral ligands. In certain embodiments, the vanadium alkylidyne complex provided by the subject invention is a non-symmetrical vanadium alkylidyne that contains two types of neutral ligands: 1) strong o-donating neutral ligands, such as trialkyl phosphines, saturated and unsaturated N-heterocyclic carbenes (NHCs), and cyclic(alkyl)(amino)carbenes (CAACs) to ensure that those ligands will be coordinated to electrophilic V center during the catalysis; and 2) weakly coordinated neutral ligands, such as pyridines, nitriles, and ethers to facilitate the initiation step and open up the coordination site for incoming alkyne. The Tolman Electronic parameter (TEP) and buried volume parameter (% V.sub.bur) can be used to identify neutral ligands that can coordinate to each specific V complex depending on present alkylidyne and anionic ligands.
(64) Representative vanadium alkylidynes provided by the subject invention include, but are not limited to, those shown in formulas (Ia)-(Ic).
(65) ##STR00011##
(66) The use of pyridine as a labile ligand that readily dissociates during the initiation step is an attractive method for preparing active catalysts. The variation of pyridine substituents can easily control the binding constant of pyridine derivatives. Furthermore, pyridine is a relatively small ligand. Thus, the % V.sub.bur of parent pyridine is only 20.6 (2.0 ), which is significantly smaller than PMe.sub.3 (26.1, 2.0 ). As a result, pyridine-containing alkylidenes can accommodate larger NHC or anionic ligands X than phosphine-containing counterparts.
(67) Another attractive class of neutral labile ligands is nitriles as nitrile-containing precatalysts exhibit higher initiation rates than analogous complexes containing pyridine. In certain embodiments, the vanadium alkylidyne provided by the subject invention contains bulky or electron-deficient nitriles to avoid possible [2+2]cycloaddition between an alkylidyne and a nitrile. In certain embodiments, the vanadium alkylidyne provided by the subject invention contains ether- and thioether-based ligands for facilitating the initiation step.
(68) In some embodiments, the vanadium alkylidyne complex provided by the subject invention can be synthesized using two strategies shown in
(69) The choice of anionic ligand(s) is an important part of the vanadium alkylidyne that affects its activity, selectivity, and stability. To achieve high catalytic performance of vanadium alkylidynes, the right balance of electronic properties is required for efficient catalysis. Because the electronegativity of V is lower compared to Mo/W, the proper ligand set is needed for vanadium alkylidyne catalysts to temper its Lewis acidity.
(70) In some embodiments, the anionic ligands with weak to moderate electron-withdrawing abilities can be beneficial. Suitable ligands may be selected based on the ligand donor parameter (LDP) (electronic properties) and/or % V.sub.bur (steric properties) in order to achieve an optimal ligand set around V for alkyne metathesis (
(71) Representative vanadium alkylidynes provided by the subject invention further include, but are not limited to, those shown in formulas (Id)-(Ig):
(72) ##STR00012##
(73) In some embodiments, these vanadium alkylidyne complexes can be synthesized using corresponding silyl chlorides to introduce the siloxide groups and protonation of the alkyl group by corresponding acid (HX). The siloxide group can also be replaced by the protonation reaction. In certain embodiments, salt metathesis can be utilized for the anionic ligand exchange.
(74) In some embodiments, the present invention provides a vanadium alkylidyne complex having a general formula of:
(75) ##STR00013## wherein each of X.sub.3 and X.sub.4 is an anionic ligand.
(76) In specific embodiments, in formula (II), each of X.sub.3 and X.sub.4 can be a monodentate ligand, or X.sub.3 and X.sub.4 together form a bidentate ligand.
(77) In certain embodiments, each of X.sub.3 and X.sub.4 is independently selected from, for example, a silane based ligand, a siloxide based ligand, a phenoxide based ligand, an alkoxide based ligand, an alkylthio based ligand, an arylthiol based ligand, a thioalkoxide based ligand, a halide based ligand, and an iminato based ligand. In certain embodiments, X.sub.3 and X.sub.4 are each independently selected from, for example, halogens, silyl, alkylthio, arylthiol, aikoxides, thioaikoxides, siloxides, NCO, NCS, NO.sub.3, and pyrrolides.
(78) In preferred embodiments, each of X.sub.3 and X.sub.4 is independently selected from CH.sub.2SiMe.sub.3, OPh, SPh, OSiPh.sub.3, OSiMePh.sub.2, OSi(p-MeOC.sub.6H.sub.4).sub.3, OSiMe.sub.2Ph, o-MeOC.sub.6H.sub.4O, m-MeOC.sub.6H.sub.4O, p-MeOC.sub.6H.sub.4O, o-MeOC.sub.6H.sub.4S, m-MeOC.sub.6H.sub.4S, p-MeOC.sub.6H.sub.4S, 2,6-(MeO).sub.2C.sub.6H.sub.3O, 2,5-(MeO).sub.2C.sub.6H.sub.3O, 2,4-(MeO).sub.2C.sub.6H.sub.3O, 2,3-(MeO).sub.2C.sub.6H.sub.3O, 3,4-(MeO).sub.2C.sub.6H.sub.3O, 3,5-(MeO).sub.2C.sub.6H.sub.3O, OC(CF.sub.3).sub.3, OCPh(CF.sub.3).sub.2, OCMe(CF.sub.3).sub.2, OCMe.sub.2CF.sub.3, OCMe.sub.3, OAd, OBu.sup.tF.sub.6, OC.sub.6F.sub.5, OTf, NO.sub.3, pyrrolyl, I, F, Cl, Br, and
(79) ##STR00014##
(80) In certain embodiments, X.sub.3 and X.sub.4 together form a bidentate ligand, such as 1,1-bi-2-naphthol (BINOL) ligand.
(81) Representative vanadium alkylidynes provided by the subject invention further include, but are not limited to, those shown in formulas (IIa)-(IIc):
(82) ##STR00015##
(83) In some embodiments, the present invention provides a vanadium alkylidyne complex, which is a cationic complex comprising one anionic ligand and three neutral ligands in addition to the VCR group, wherein the vanadium alkylidyne complex has a structure of:
(84) ##STR00016## wherein L.sub.3, L.sub.4 and L.sub.5 are neutral ligands, and optionally, one of L.sub.3, L.sub.4 and L.sub.5 can be absent; X.sub.5 is an anionic ligand; and R is alkyl, aryl or Si(R.sup.a).sub.3, wherein R.sup.a is selected from, for example, alkyl, substituted alkyl, aryl, and substituted aryl. In a specific embodiment, R is SiMe.sub.3. In certain embodiments, each of X.sub.5, L.sub.3, L.sub.4 and L.sub.5 is a monodentate ligand, or two or three of X.sub.5, L.sub.3, L.sub.4 and L.sub.5 together form a bidentate ligand or a tridentate ligand.
(85) In certain embodiments, X.sub.5 is selected from, for example, a silane based ligand, a siloxide based ligand, a phenoxide based ligand, an alkoxide based ligand, an alkylthio based ligand, an arylthiol based ligand, a thioalkoxide based ligand, a halide based ligand, and an iminato based ligand. In certain embodiments, X.sub.5 is selected from, for example, halogens, silyl, alkylthio, arylthiol, alkoxides, thioalkoxides, siloxides, NCO, NCS, NO.sub.3, and pyrrolides.
(86) In preferred embodiments, X.sub.5 is selected from, for example, CH.sub.2SiMe.sub.3, OPh, SPh, OSiPh.sub.3, OSiMePh.sub.2, OSi(p-MeOC.sub.6H.sub.4).sub.3, OSiMe.sub.2Ph, o-MeOC.sub.6H.sub.4O, m-MeOC.sub.6H.sub.4O, p-MeOC.sub.6H.sub.4O, o-MeOC.sub.6H.sub.4S, m-MeOC.sub.6H.sub.4S, p-MeOC.sub.6H.sub.4S, 2,6-(MeO).sub.2C.sub.6H.sub.3O, 2,5-(MeO).sub.2C.sub.6H.sub.3O, 2,4-(MeO).sub.2C.sub.6H.sub.3O, 2,3-(MeO).sub.2C.sub.6H.sub.3O, 3,4-(MeO).sub.2C.sub.6H.sub.3O, 3,5-(MeO).sub.2C.sub.6H.sub.3O, OC(CF.sub.3).sub.3, OCPh(CF.sub.3).sub.2, OCMe(CF.sub.3).sub.2, OCMe.sub.2CF.sub.3, OCMe.sub.3, OAd, OBu.sup.tF.sub.6, OC.sub.6F.sub.5, OTf, pyrrolyl, I, F, Cl, Br, NO.sub.3, and
(87) ##STR00017##
(88) In certain embodiments, each of L.sub.3, L.sub.4, and L.sub.5 is independently selected from, for example, a pyridine based ligand, a nitrile based ligand, an ether based ligand, a thioether based ligand, a phosphine (such as trialkyl phosphine) based ligand, a saturated and unsaturated N-heterocyclic carbene (NHC) based ligand, and a cyclic(alkyl)(amino)carbene (CAAC) based ligand. In preferred embodiments, L.sub.3, L.sub.4, and L.sub.5 are each independently selected from, for example, phosphines, NHCs, pyridines, nitriles, ethers, thioethers, CAACs and substituted thereof.
(89) In specific embodiments, phosphines have a general structure of P(R.sub.1)(R.sub.2)(R.sub.3), where R.sub.1, R.sub.2, and R.sub.3 are each independently selected from hydrogen, alkyl, substituted alkyl, aryl and substituted aryl.
(90) In specific embodiments, the NHC is
(91) ##STR00018##
wherein R.sub.4, R.sub.5, R.sub.6, R.sub.7 and R.sub.8 are independently selected from hydrogen, alkyl, substituted alkyl, cycloalkyl, substituted cycloalkyl, aryl, and substituted aryl.
(92) In certain embodiments, pyridines have a structure of
(93) ##STR00019##
wherein R.sub.6, R.sub.7, R.sub.8, R.sub.9, R.sub.10 are each independently selected from, for example, hydrogen, halogens, alkyl, substituted alkyl, hydorxyl, acyl, and NH.sub.2.
(94) In certain embodiments, nitriles are selected from, for example,
(95) ##STR00020##
wherein R.sub.6, R.sub.7, R.sub.8, R.sub.9, R.sub.10 are each independently selected from hydrogen, halogens, alkyl, substituted alkyl, alkoxides, aryl, substituted aryl, hydorxyl, acyl, and NH.sub.2.
(96) In a specific embodiment, each of L.sub.3, L.sub.4 and L.sub.5 is independently selected from, for example, PMe.sub.3, PEt.sub.3, NC.sub.5H.sub.5, NC.sub.5H.sub.4Br, NCCMe.sub.3, Me.sub.3,
(97) ##STR00021##
(98) In some embodiments, the present invention provides a cationic vanadium alkylidyne complex having a general formula of:
(99) ##STR00022## wherein X.sub.5 is an anionic ligand, and each of L.sub.3, L.sub.4 and L.sub.5 is a neutral ligand, and wherein X.sub.5 is selected from a silane based ligand, a siloxide based ligand, a phenoxide based ligand, an alkoxide based ligand, an alkylthio based ligand, an arylthiol based ligand, a thioalkoxide based ligand, a halide based ligand, and an iminato based ligand. Preferably, X.sub.5 is selected from CH.sub.2SiMe.sub.3, OPh, SPh, OSiPh.sub.3, OSiMePh.sub.2, OSi(p-MeOC.sub.6H.sub.4).sub.3, OSiMe.sub.2Ph, o-MeOC.sub.6H.sub.4O, m-MeOC.sub.6H.sub.4O, p-MeOC.sub.6H.sub.4O, o-MeOC.sub.6H.sub.4S, m-MeOC.sub.6H.sub.4S, p-MeOC.sub.6H.sub.4S, 2,6-(MeO).sub.2C.sub.6H.sub.3O, 2,5-(MeO).sub.2C.sub.6H.sub.3O, 2,4-(MeO).sub.2C.sub.6H.sub.3O, 2,3-(MeO).sub.2C.sub.6H.sub.3O, 3,4-(MeO).sub.2C.sub.6H.sub.3O, 3,5-(MeO).sub.2C.sub.6H.sub.3O, OC(CF.sub.3).sub.3, OCPh(CF.sub.3).sub.2, OCMe(CF.sub.3).sub.2, OCMe.sub.2CF.sub.3, OCMe.sub.3, OAd, OBu.sup.tF.sub.6, OC.sub.6F.sub.5, OTf, pyrrolyl, I, F, Cl, Br, NO.sub.3, and
(100) ##STR00023##
(101) In certain embodiments, each of L.sub.3, L.sub.4 and L.sub.5 is independently selected from a pyridine based ligand, a nitrile based ligand, an ether based ligand, a thioether based ligand, a phosphine (such as trialkyl phosphine) based ligand, a saturated and unsaturated N-heterocyclic carbene (NHC) based ligand, and a cyclic(alkyl)(amino)carbene (CAAC) based ligand. Preferably, each of L.sub.3, L.sub.4 and L.sub.5 is independently selected from PMe.sub.3, PEt.sub.3, NC.sub.5H.sub.5, NC.sub.5H.sub.4Br, NCCMe.sub.3,
(102) ##STR00024##
(103) In certain embodiments, two of L.sub.3, L.sub.4 and L.sub.5 together form a bidentate ligand selected from bipyridine ligand such as 4,4-bis(tert-butyl)-2,2-bipyridine (dtbbpy), and phenanthroline ligand.
(104) In a specific embodiment, one of L.sub.3, L.sub.4 and L.sub.5 can be absent.
(105) Representative vanadium alkylidyne cationic complexes provided by the subject invention include, but are not limited to, those shown in formulas (IIIa)-(IIId) (anions are not shown for simplicity).
(106) ##STR00025##
(107) In some embodiments, these vanadium alkylidyne cationic complexes can be synthesized from the corresponding vanadium alkylidyne neutral complexes V(CR)X.sub.2L.sub.2 by utilizing Brookhart's acid or NaBArF to replace one anionic ligand X with one neutral ligand L.
(108) In some embodiments, the present invention provides a vanadium alkylidyne complex, which is an anionic complex containing three anionic ligands and one neutral ligand, wherein the anionic vanadium alkylidyne complex has a structure of:
(109) ##STR00026## wherein L.sub.6 is a neutral ligand; X.sub.6, X.sub.7, and X.sub.8 are anionic ligands; and R is alkyl, aryl or Si(R.sup.a).sub.3, wherein R.sup.a is selected from, for example, alkyl, substituted alkyl, aryl, and substituted aryl. In a specific embodiment, R is SiMe.sub.3. In certain embodiments, each of X.sub.6, X.sub.7, X.sub.8 and L.sub.6 is a monodentate ligand, or two or three of X.sub.6, X.sub.7, X.sub.8 and L.sub.6 together form a bidentate ligand or a tridentate ligand. In specific embodiments, two of X.sub.6, X.sub.7 and X.sub.8 together (e.g., X.sub.6 and X.sub.7, and X.sub.7 and X.sub.8) form a bidentate ligand, such as 1,1-bi-2-naphthol (BINOL) ligand.
(110) In certain embodiments, each of X.sub.6, X.sub.7, and X.sub.8 is independently selected from, for example, a silane based ligand, a siloxide based ligand, a phenoxide based ligand, an alkoxide based ligand, an alkylthio based ligand, an arylthiol based ligand, a thioalkoxide based ligand, a halide based ligand, and an iminato based ligand. In certain embodiments, X.sub.6, X.sub.7, and X.sub.8 are each independently selected from, for example, halogens, silyl, alkylthio, arylthiol, alkoxides, thioalkoxides, siloxides, NCO, NCS, NO.sub.3, and pyrrolides.
(111) In preferred embodiments, X.sub.6, X.sub.7, and X.sub.8 are each independently selected from, for example, CH.sub.2SiMe.sub.3, OPh, SPh, OSiPh.sub.3, OSiMePh.sub.2, OSi(p-MeOC.sub.6H.sub.4).sub.3, OSiMe.sub.2Ph, o-MeOC.sub.6H.sub.4O, m-MeOC.sub.6H.sub.4O, p-MeOC.sub.6H.sub.4O, o-MeOC.sub.6H.sub.4S, m-MeOC.sub.6H.sub.4S, p-MeOC.sub.6H.sub.4S, 2,6-(MeO).sub.2C.sub.6H.sub.3O, 2,5-(MeO).sub.2C.sub.6H.sub.3O, 2,4-(MeO).sub.2C.sub.6H.sub.3O, 2,3-(MeO).sub.2C.sub.6H.sub.3O, 3,4-(MeO).sub.2C.sub.6H.sub.3O, 3,5-(MeO).sub.2C.sub.6H.sub.3O, OC(CF.sub.3).sub.3, OCPh(CF.sub.3).sub.2, OCMe(CF.sub.3).sub.2, OCMe.sub.2CF.sub.3, OCMe.sub.3, OAd, OBu.sup.tF.sub.6, OC.sub.6F.sub.5, OTf, pyrrolyl, I, F, Cl, Br, NO.sub.3, and
(112) ##STR00027##
(113) In certain embodiments, L.sub.6 is selected from, for example, a pyridine based ligand, a nitrile based ligand, an ether based ligand, a thioether based ligand, a phosphine (such as trialkyl phosphine) based ligand, a saturated and unsaturated N-heterocyclic carbene (NHC) based ligand, and a cyclic(alkyl)(amino)carbene (CAAC) based ligand. In preferred embodiments, L.sub.6 is selected from, for example, phosphines, NHCs, pyridines, nitriles, ethers, thioethers, CAACs and substituted thereof.
(114) In some embodiments, the present invention provides an anionic vanadium alkylidyne complex having a general formula of:
(115) ##STR00028## wherein each of X.sub.6, X.sub.7 and X.sub.8 is an anionic ligand, and L.sub.6 is a neutral ligand; wherein each of X.sub.6, X.sub.7 and X.sub.8 is independently selected from a silane based ligand, a siloxide based ligand, a phenoxide based ligand, an alkoxide based ligand, an alkylthio based ligand, an arylthiol based ligand, a thioalkoxide based ligand, a halide based ligand, and an iminato based ligand. Preferably, each of X.sub.6, X.sub.7 and X.sub.8 is independently selected from CH.sub.2SiMe.sub.3, OPh, SPh, OSiPh.sub.3, OSiMePh.sub.2, OSi(p-MeOC.sub.6H.sub.4).sub.3, OSiMe.sub.2Ph, o-MeOC.sub.6H.sub.4O, m-MeOC.sub.6H.sub.4O, p-MeOC.sub.6H.sub.4O, o-MeOC.sub.6H.sub.4S, m-MeOC.sub.6H.sub.4S, p-MeOC.sub.6H.sub.4S, 2,6-(MeO).sub.2C.sub.6H.sub.3O, 2,5-(MeO).sub.2C.sub.6H.sub.3O, 2,4-(MeO).sub.2C.sub.6H.sub.3O, 2,3-(MeO).sub.2C.sub.6H.sub.3O, 3,4-(MeO).sub.2C.sub.6H.sub.3O, 3,5-(MeO).sub.2C.sub.6H.sub.3O, OC(CF.sub.3).sub.3, OCPh(CF.sub.3).sub.2, OCMe(CF.sub.3).sub.2, OCMe.sub.2CF.sub.3, OCMe.sub.3, OAd, OBu.sup.tF.sub.6, OC.sub.6F.sub.5, OTf, pyrrolyl, I, F, Cl, Br, NO.sub.3, and
(116) ##STR00029##
(117) In formula (IV), each of X.sub.6, X.sub.7, X.sub.8 and L.sub.6 can be a monodentate ligand, or two or three of X.sub.6, X.sub.7, X.sub.8 and L.sub.6 together form a bidentate ligand or a tridentate ligand. In certain embodiments, two of X.sub.6, X.sub.7 and X.sub.8 together form a bidentate ligand, such as 1,1-bi-2-naphthol (BINOL) ligand.
(118) In certain embodiments, L.sub.6 is selected from a pyridine based ligand, a nitrile based ligand, an ether based ligand, a thioether based ligand, a phosphine (such as trialkyl phosphine) based ligand, a saturated and unsaturated N-heterocyclic carbene (NHC) based ligand, and a cyclic(alkyl)(amino)carbene (CAAC) based ligand. Preferably, L.sub.6 is selected from PMe.sub.3, PEt.sub.3, NC.sub.5H.sub.5, NC.sub.5H.sub.4Br, NCCMe.sub.3,
(119) ##STR00030##
(120) Representative anionic vanadium alkylidyne complexes provided by the subject invention include, but are not limited to, those shown in formulas (IVa)-(IVb) (cations are not shown for simplicity).
(121) ##STR00031##
(122) In some embodiments, these vanadium alkylidyne anionic complexes can be synthesized, for example, from neutral complexes V(CR)X.sub.2L.sub.2 and corresponding salts MX (M=Li, Na, K, R.sub.4N.sup.+, R.sub.4P.sup.+, (Ph.sub.3P).sub.2N.sup.+, etc.) in the presence of Lewis acids to remove one neutral ligand L.
(123) In some embodiments, the vanadium alkylidyne complex provided by the present invention contains a polydentate ligand (bi- or tridentate ligand) for preventing ligand dissociation and preserving five-coordinate MCBD. Representative vanadium alkylidynes containing a polydentate ligand provided by the subject invention include, but are not limited to, those shown in formulas (Va)-(Ve) (counterions are not shown for simplicity).
(124) ##STR00032##
(125) In some embodiments, these vanadium alkylidynes can be synthesized from neutral complexes V(CR)X.sub.2L.sub.2 and corresponding bi- and tridentate ligands by protonation or salt metathesis to introduce anionic moieties and ligand exchange to introduce neutral ligands.
(126) In some embodiments, the vanadium alkylidyne presented by the subject invention is a five-coordinated complex containing four ligands in addition to the VCR group, wherein each of the four ligands is an anionic ligand or a neutral ligand. In certain embodiments, the vanadium alkylidyne presented by the subject invention is a four-coordinated complex comprising three ligands in addition to the VCR group, wherein each of the three ligands is an anionic ligand or a neutral ligand.
(127) In some embodiments, the subject invention provides a vanadium alkylidyne complex comprising two anionic ligands and one neutral ligand in addition to the VCR group, which has a structure of:
(128) ##STR00033## wherein L is a neutral ligand; X.sub.1 and X.sub.2 are anionic ligands; and R is alkyl, aryl or Si(R.sup.a).sub.3, wherein R.sup.a is selected from, for example, alkyl, substituted alkyl, aryl, and substituted aryl. In a specific embodiment, R is SiMe.sub.3. In certain embodiments, each of X.sub.1, X.sub.2, and L is a monodentate ligand, or two of X.sub.1, X.sub.2, and L together form a bidentate ligand or a tridentate ligand.
(129) In certain embodiments, each of X.sub.1 and X.sub.2 is independently selected from, for example, a silane based ligand, a siloxide based ligand, a phenoxide based ligand, an alkoxide based ligand, an alkylthio based ligand, an arylthiol based ligand, a thioalkoxide based ligand, a halide based ligand, and an iminato based ligand. In certain embodiments, X.sub.1 and X.sub.2 are each independently selected from, for example, halogens, silyl, alkylthio, arylthiol, alkoxides, thioalkoxides, siloxides, NCO, NCS, NO.sub.3, and pyrrolides.
(130) In some embodiments, the vanadium alkylidyne complex provided by the present invention comprises a tripodal ligand to form a trigonal-pyramidal geometry. One of the crucial features of a tripodal scaffold is the destabilization of the MCBD intermediate and the formation of metallatetrahedrane (MTd), which opens up an alternative mechanism for alkyne metathesis. Since the stability of MCBD is the main challenge in V-mediated alkyne metathesis, introducing tripodal ligands can be highly beneficial for reactivity.
(131) Representative vanadium alkylidynes containing a tripodal ligand provided by the subject invention include, but are not limited to, those shown in formulas (VIa)-(VIc) (anion in the cationic complex is not shown for simplicity).
(132) ##STR00034##
(133) In some embodiments, these vanadium alkylidynes can be synthesized from neutral complexes V(CR)X.sub.2L.sub.2 and corresponding tripodal ligands by protonation or salt metathesis to introduce anionic moieties and ligand exchange to introduce neutral ligands.
(134) Methods of Synthesizing Vanadium Alkylidyne Complexes
(135) In one embodiment, the subject invention provides methods for synthesizing vanadium alkylidyne complexes of the subject invention. The method described herein can be used to synthesize vanadium alkylidyne complexes that are neutral, cationic or anionic.
(136) The present invention provides simple, scalable, and reproducible methods for converting a V(+5) oxo complex to a V(+5) alkylidyne in three steps without altering the oxidation state of the metal center. This method involves a unique transformation using the anionic V alkylidene intermediate, which ultimately leads to a reduction in the bond order between V and the oxo ligand. Such transformation is rare, considering the high strength of the VO bond.
(137) In specific embodiments, the method of the subject invention involves creating an anionic V alkylidene complex that contains a nucleophilic oxygen atom, making it reactive toward electrophiles such as silyl chlorides. Subsequent -hydrogen abstraction from the alkylidene results in the formation of alkylidynes.
(138) In a specific embodiment, the subject invention provides a method of synthesizing the vanadium alkylidyne complex of the subject invention, in which the V oxo trialkyl complex VO(CH.sub.2TMS).sub.3 reacts with strong bases, including MN(TMS).sub.2 (M=Li or K), or organolithium reagents (RLi), to form V anionic alkylidene. Those complexes react with R.sub.3SiCl in the presence of bipyridine to form V alkylidynes. Then, V alkylidynes react with alkynes to form metallacyclobutadiene, a key intermediate in alkyne metathesis.
(139) In specific embodiments, the vanadium alkylidyne complex provided by the subject invention can be synthesized using two strategies shown in
(140) In some embodiments, the present invention provides a method of synthesizing a vanadium alkylidyne complex, the method comprising steps of: (1) reacting a vanadium oxo trialkoxyl complex with an alkylating agent to form a vanadium oxo trialkyl complex; (2) treating the vanadium oxo trialkyl complex with an alkaline reagent in the presence of one or more neutral ligands (e.g., a bipyridine ligand) to form an anionic vanadium alkylidene intermediate; and (3) reacting the anionic vanadium alkylidene intermediate with an electrophile.
(141) In certain embodiments, the vanadium oxo trialkoxyl complex is selected from, for example, VO(OCH.sub.3).sub.3 (Vanadium oxo trimethoxide), VO(OCH.sub.2CH.sub.3).sub.3 (Vanadium oxo triethoxide), VO(O.sup.iPr).sub.3 (Vanadium oxo triisopropoxide or vanadium oxytriisopropoxide), VO(O.sup.tBu).sub.3 (Vanadium oxo tri-tert-butoxide), and VO(OC.sub.6H.sub.5).sub.3 (Vanadium oxo triphenoxide). In certain embodiments, the alkylating agent is selected from, for example, TMSCH.sub.2Li, TMSCH.sub.2MgCl, (TMSCH.sub.2).sub.2Zn, (TMSCH.sub.2).sub.3Al, and any combination thereof.
(142) The ratio of the vanadium oxo trialkoxyl complex to the alkylating agent is a key factor to avoid the reduction of V species. In certain embodiments, about 1.0-3.0, about 1.1-2.9, about 1.2-2.9, about 1.3-2.9, about 1.4-2.9, about 1.5-2.9, about 1.6-2.9, about 1.7-2.9, about 1.8-2.9, about 1.9-2.9, about 2.0-2.9, about 2.1-2.9, about 2.2-2.9, about 2.3-2.9, about 2.4-2.9, about 2.5-2.9, about 2.6-2.9, about 2.7-2.9, about 2.8-2.9, about 1.0-2.8, about 1.0-2.7, about 1.0-2.6, about 1.0-2.5, about 1.0-2.4, about 1.0-2.3, about 1.0-2.2, about 1.0-2.1, about 1.0-2.0, about 1.0-1.9, about 1.0-1.8, about 1.0-1.7, about 1.0-1.6, about 1.0-1.5, about 1.0-1.4, about 1.0-1.3, about 1.0-1.2, or about 1.0-1.1 equivalents of the alkylating agent are used in step (1) for every 1 equivalent of the vanadium oxo trialkoxyl complex. In a specific embodiment, the amount of the alkylating agent used in step (1) is not 3.0 equivalents for every 1 equivalent of the vanadium oxo trialkoxyl complex. In certain embodiments, about 1.7-2.9, about 1.8-2.8, about 1.9-2.7, about 2.0-2.6, about 2.1-2.5, or about 2.2-2.4 equivalents of the alkylating agent are used in step (1) for every 1 equivalent of the vanadium oxo trialkoxyl complex. In preferred embodiments, about 2.3 equivalents of the alkylating agent are used in step (1) for every 1 equivalent of the vanadium oxo trialkoxyl complex.
(143) In one embodiment, reacting a vanadium oxo trialkoxyl complex with an alkylating agent to form a vanadium oxo trialkyl complex comprises mixing the vanadium oxo trialkoxyl complex with the alkylating agent or adding the alkylating agent to the vanadium oxo trialkoxyl complex.
(144) In certain embodiments, the reaction of step (1) can be carried out in a solvent selected from, for example, pentane, hexane, heptane, cyclohexane, isohexane, diethyl ether (Et.sub.2O), tetrahydrofuran (THF), dioxane, dimethyl ether (DME), methyl tert-butyl ether (MTBE), and any combination thereof.
(145) In certain embodiments, the solvent is a mixture of a solvent selected from pentane, hexane, heptane, cyclohexane and isohexane, and a solvent selected from Et.sub.2O, THF, dioxane, DME and MTBE, with two solvents mixed at a volume ratio of about 8:1 to about 2:1, about 7:1 to about 2:1, about 6:1 to about 2:1, about 8:1 to about 3:1, about 8:1 to about 4:1, about 8:1 to about 5:1, about 7:1 to about 3:1, about 6:1 to about 3:1, about 7:1 to about 4:1, about 7:1 to about 5:1, about 6:1 to about 4:1, or about 6:1 to about 5:1.
(146) In certain embodiments, step (1) comprises mixing the vanadium oxo trialkoxyl complex with the alkylating agent in a solvent at a temperature of about 60 to 90 C., stirring the reaction mixture at the above temperature for about 10-60 mins, and then allowing the reaction mixture to stir at a temperature of about 10 to 40 C. for an additional about 10-60 mins. In some embodiments, the vanadium oxo trialkoxyl complex can be mixed with the alkylating agent in the solvent at a temperature of about 60 to 90 C., about 65 to 90 C., about 70 to 90 C., about 75 to 90 C., about 60 to 85 C., about 60 to 80 C., about 65 to 85 C., about 70 to 85 C., about 75 to 85 C., or about 75 to 80 C.
(147) In some embodiments, step (1) comprises stirring the reaction mixture at a temperature of about 60 to 90 C. for about 10-60 mins, about 20-60 mins, about 30-60 mins, about 10-50 mins, about 10-40 mins, about 10-30 mins, about 20-50 mins, about 30-50 mins, about 20-40 mins, or about 20-30 mins. In some embodiments, step (1) further comprises stirring the reaction mixture at a temperature of about 10 to 40 C., about 20 to 40 C., about 20 to 30 C., or about 20 to 25 C. for an additional about 10-60 mins, about 20-60 mins, about 30-60 mins, about 10-50 mins, about 10-40 mins, about 10-30 mins, about 20-50 mins, about 30-50 mins, about 20-40 mins, or about 20-30 mins.
(148) In certain embodiments, the reaction of step (1) is carried out under an inert atmosphere of argon or nitrogen.
(149) In specific embodiments, the reaction of step (1) produces a vanadium oxo trialkyl complex such as VO(CH.sub.2TMS).sub.3, which is then used in step (2) as a reactant. In some embodiments, step (1) further comprises purifying the vanadium oxo trialkyl complex such as VO(CH.sub.2TMS).sub.3 via crystallization, distillation, chromatography, extraction, sublimation, precipitation, filtration, dialysis, or any combination thereof. In certain embodiments, the vanadium oxo trialkyl complex such as VO(CH.sub.2TMS).sub.3, obtained from step (1) can be purified by dissolving in Et.sub.2O and recrystallizing at about 35 C.
(150) In certain embodiments, treating the vanadium oxo trialkyl complex with an alkaline reagent in the presence of one or more neutral ligands comprises mixing the alkaline reagent and one or more neutral ligands with the vanadium oxo trialkyl complex or adding the alkaline reagent and one or more neutral ligands to the product of step (1).
(151) In specific embodiments, the one or more neutral ligands are selected from bipyridine ligands. In certain embodiments, the bipyridine ligand is selected from, for example, 2,2-bipyridine (bipy or bpy), 4,4-dimethyl-2,2-bipyridine, 4,4-di-tert-butyl-2,2-bipyridine (dtbbpy), 5,5-dimethyl-2,2-bipyridine, 6,6-dimethyl-2,2-bipyridine, 4,4-di-tert-butyl-6,6-dimethyl-2,2-bipyridine, 4,4-dicarboxy-2,2-bipyridine, 4,4-diamino-2,2-bipyridine, 3,3-bipyridine, and 6,6-bis(phenyl)-2,2-bipyridine.
(152) In certain embodiments, the alkaline reagent is MN(TMS).sub.2 (M=Li or K), or an organolithium reagent (RLi). Examples of the organolithium reagent include, but are not limited to, methyllithium (MeLi), ethyllithium (EtLi), n-butyllithium (n-BuLi), sec-butyllithium (s-BuLi), tert-butyllithium (t-BuLi), phenyllithium (PhLi), o-tolyllithium (o-CH.sub.3C.sub.6H.sub.4Li), m-tolyllithium (m-CH.sub.3C.sub.6H.sub.4Li), p-tolyllithium (p-CH.sub.3C.sub.6H.sub.4Li), lithium naphthalenide (LiC.sub.10H.sub.8), vinyllithium (CH.sub.2CHLi), lithium (trimethylsilyl) ethynyllithium (Me.sub.3SiCCLi), lithium diisopropylamide (LDA, (.sup.iPr).sub.2NLi), lithium tetramethylpiperidide (LiTMP), and lithium hexamethyldisilazide (LiHMDS).
(153) In certain embodiments, for every 1 equivalent of the vanadium oxo trialkyl complex such as VO(CH.sub.2TMS).sub.3, about 1.0-1.5, about 1.0-1.4, about 1.0-1.3, or about 1.0-1.2 equivalents of the alkaline reagent, and about 1.0-1.5, about 1.0-1.4, about 1.0-1.3, about 1.0-1.2, or about 1.0-1.1 equivalents of the bipyridine ligand are used. In preferred embodiments, about 1.1 equivalents of the alkaline reagent and about 1.0 equivalent of the bipyridine ligand are used for every 1 equivalent of the vanadium oxo trialkyl complex such as VO(CH.sub.2TMS).sub.3.
(154) In certain embodiments, the reaction of step (2) is carried out in a solvent selected from, for example, pentane, hexane, heptane, cyclohexane, isohexane, diethyl ether (Et.sub.2O), tetrahydrofuran (THF), dioxane, dimethyl ether (DME), methyl tert-butyl ether (MTBE), and any combination thereof. In certain embodiments, the solvent suitable for use in step (2) is a mixture of a solvent selected from pentane, hexane, heptane, cyclohexane and isohexane, and a solvent selected from Et.sub.2O, THF, dioxane, DME and MTBE, with the two solvents mixed at a volume ratio of about 2:1 to about 1:2, about 1.5:1 to about 1:2, about 1:1 to about 1:2, about 1:1.5 to about 1:2, about 2:1 to about 1:1.5, about 2:1 to about 1:1, about 1.5:1 to about 1:1.5.
(155) In certain embodiments, step (2) comprises mixing the alkaline reagent and the vanadium oxo trialkyl complex such as VO(CH.sub.2TMS).sub.3, at a temperature of about 10 to 40 C., about 20 to 40 C., about 20 to 30 C., or about 20 to 25 C., adding the bipyridine ligand to the obtained mixture at the above temperature, and then stirring the reaction mixture at the above temperature for at least about 5-30 mins, about 10-25 mins, about 10-20 mins, or about 10-15 mins.
(156) In some embodiments, step (2) further comprises purifying the anionic vanadium alkylidene intermediate via crystallization, distillation, chromatography, extraction, sublimation, precipitation, filtration, dialysis, or any combination thereof. In certain embodiments, the anionic vanadium alkylidene intermediate obtained from step (2) can be purified by recrystallization from pentane, Et.sub.2O, or isopropyl ether (.sup.iPr.sub.2O). The anionic vanadium alkylidene intermediate contains a nucleophilic oxygen atom, making it reactive toward electrophiles such as silyl chlorides.
(157) In certain embodiments, reacting the anionic vanadium alkylidene intermediate with an electrophile comprises mixing the anionic vanadium alkylidene intermediate with the electrophile, adding the electrophile to the anionic vanadium alkylidene intermediate or adding the electrophile to the product of step (2).
(158) In certain embodiments, the electrophile is a silyl chloride. Examples of silyl chlorides include, but are not limited to, SiMe.sub.2PhCl, SiMePh.sub.2Cl, and SiPh.sub.3Cl.
(159) In certain embodiments, about 1.0-1.5, about 1.0-1.4, about 1.0-1.3, about 1.0-1.2, or about 1.0-1.1 equivalents of the electrophile are used in step (3) for every 1 equivalent of the anionic vanadium alkylidene intermediate. In preferred embodiments, about 1.0 equivalent of the electrophile is used in step (3) for every 1 equivalent of the anionic vanadium alkylidene intermediate.
(160) In certain embodiments, the reaction of step (3) can be carried out in a solvent selected from Et.sub.2O, THF, dioxane, DME, MTBE, and any combination thereof.
(161) In certain embodiments, step (3) comprises dissolving the anionic vanadium alkylidene intermediate in the solvent, cooling the obtained solution to about 20 to 50 C., about 20 to 45 C., about 20 to 40 C., about 25 to 50 C., about 30 to 50 C., or about 30 to 40 C., adding the electrophile at the above temperature, and stirring the reaction mixture at a temperature of about 10 to 40 C., about 20 to 40 C., about 20 to 30 C., or about 20 to 25 C. for at least about 5-30 mins, about 10-25 mins, about 10-20 mins, or about 10-15 mins.
(162) In some embodiments, step (3) further comprises purifying the product via crystallization, distillation, chromatography, extraction, sublimation, precipitation, filtration, dialysis, or any combination thereof. In certain embodiments, the product obtained from step (3) can be purified by recrystallization from hexane or Et.sub.2O.
(163) In some embodiments, the method of synthesizing a vanadium alkylidyne further comprises a step of: (4) reacting the product of step (3) with an alcohol reagent or a phenol reagent.
(164) In certain embodiments, the alcohol reagent or the phenol reagent is selected from, for example, silanols, phenols, and thiophenols. Examples of the alcohol reagents or phenol reagents include, but are not limited to, SiPh.sub.3OH, SiMePh.sub.2OH, Si(p-MeOC.sub.6H.sub.4).sub.3OH, SiMe.sub.2PhOH, o-MeOC.sub.6H.sub.4OH, m-MeOC.sub.6H.sub.4OH, p-MeOC.sub.6H.sub.4OH, o-MeOC.sub.6H.sub.4SH, m-MeOC.sub.6H.sub.4SH, p-MeOC.sub.6H.sub.4SH, 2,6-(MeO).sub.2C.sub.6H.sub.3OH, 2,5-(MeO).sub.2C.sub.6H.sub.3OH, 2,4-(MeO).sub.2C.sub.6H.sub.3OH, 2,3-(MeO).sub.2C.sub.6H.sub.3OH, 3,4-(MeO).sub.2C.sub.6H.sub.3OH, and 3,5-(MeO).sub.2C.sub.6H.sub.3OH.
(165) In some embodiments, the method for synthesizing the vanadium alkylidyne complexes of the subject invention involves the use of corresponding silyl chlorides to introduce the siloxide groups and protonation of the alkyl group by corresponding acid (HX). The siloxide group can also be replaced by the protonation reaction. In certain embodiments, salt metathesis can be utilized for the anionic ligand exchange.
(166) In some embodiments, the method for synthesizing the vanadium alkylidyne complexes of the subject invention further comprises replacing an anionic ligand X with a neutral ligand L of the vanadium alkylidyne neutral complexes V(CR)X.sub.2L.sub.2 by utilizing, for example, Brookhart's acid or NaBArF in the presence of the neutral ligand L to arrive at a vanadium alkylidyne cationic complexes. In a specific embodiment, such step comprises mixing the method for synthesizing the vanadium alkylidyne complexes of the subject invention further comprises with an acid, e.g., Brookhart's acid and NaBArF, and a neutral ligand.
(167) In some embodiments, the method for synthesizing the vanadium alkylidyne complexes of the subject invention further comprises converting the vanadium alkylidyne neutral complexes V(CR)X.sub.2L.sub.2 to vanadium alkylidyne anionic complexes by mixing or adding corresponding salts MX (M=Li, Na, K, R.sub.4N.sup.+, R.sub.4P.sup.+, (Ph.sub.3P).sub.2N.sup.+, etc.) in the presence of Lewis acids to remove one neutral ligand L.
(168) In some embodiments, the method of the subject invention further comprises exchanging ligands of the vanadium alkylidyne neutral complexes with bi- and tridentate ligands by protonation or salt metathesis
(169) In some embodiments, the method of the subject invention further comprises exchanging ligands of the vanadium alkylidyne neutral complexes with tripodal ligands by protonation or salt metathesis.
(170) Applications
(171) In one embodiment, the subject invention provides a method of using compounds/complexes having a metal center of a first-row metal, such as vanadium, for synthesizing unsaturated compounds via metathesis reactions.
(172) In some embodiments, the method for synthesizing an unsaturated compound via a metathesis reaction (e.g., olefin metathesis or alkyne metathesis) comprises contacting at least one, two or three substrates with a compound/complex having a metal center selected from first-row metals or the composition comprising the compound/complex having a metal center selected from first-row metals. In specific embodiments, the substrates are selected from olefins and alkynes.
(173) In one embodiment, the subject invention provides a method of using the vanadium alkylidyne complexes of the subject invention in various metathesis reactions (e.g., alkyne metathesis), the method comprising contacting/mixing at least one substrate with a vanadium alkylidyne complex of the subject invention or the composition comprising a vanadium alkylidyne complex of the subject invention.
(174) In certain embodiments, the substates are unsaturated compounds such as olefins and alkynes. In specific embodiments, the substrates are compounds having an internal alkyne or a terminal alkyne.
(175) The vanadium alkylidyne complexes as prepared and described herein can serve as catalysts in various metathesis reactions. Thus, the present invention also provides methods and processes involving the use of such new catalytic species, or any mixture of such species, or such catalytic systems, in a wide range of organic synthesis reactions including the metathesis of unsaturated compounds such as olefins and alkynes, and reactions involving the transfer of an atom or group to an ethylenically or acetylenically unsaturated compound or another reactive substrate, such as atom transfer radical polymerization, atom transfer radical addition, vinylation, cyclopropanation of ethylenically unsaturated compounds, and the like.
(176) In one embodiment, the subject invention provides a method of performing a metathesis reaction of an unsaturated compound in the presence of a catalytic component, in particular, the vanadium alkylidyne complexes described and prepared herein, comprising contacting the unsaturated compound with the catalytic component or mixing the unsaturated compound with the catalytic component.
(177) In preferred embodiments, the vanadium alkylidyne complex described herein is the only catalytic component used in the metathesis reaction.
(178) The metathesis reaction according to the present invention can be olefin metathesis reactions or alkyne metathesis reactions, in particular, nitrile-alkyne metathesis, phosphaalkyne-alkyne metathesis, acyclic diyne metathesis polymerization (ADIMET), ring expansion alkyne metathesis polymerization (REAMP), and ring-opening alkyne metathesis polymerization (ROAMP). Accordingly, the unsaturated compound can be an olefin or an alkyne, for example, an internal alkyne such as ArCCMe (Ar=Ph or p-MeOC.sub.6H.sub.4), or a terminal alkyne. Employing these vanadium alkylidyne complexes in alkyne metathesis reactions, leading to the formation of metallacyclobutadiene intermediates essential for catalytic efficiency. Advantageously, the reversible nature of alkyne metathesis allows the chemical recycling of resulting materials.
(179) The metathesis reaction of an unsaturated compound according to the present invention may be conducted in a continuous, semi-continuous, or batch manner and may involve a liquid and/or gas recycling operation, as desired. In particular, the metathesis reaction may be carried out in a liquid reaction medium that contains a solvent for the active catalyst, preferably one in which the reactants, including catalyst, are substantially soluble at the reaction temperature.
(180) In one embodiment, the subject invention provides a method for synthesizing an unsaturated compound via a metathesis reaction, the method comprising contacting at least one, two, or three substrates with the vanadium alkylidyne complex of the subject invention or the composition comprising the vanadium alkylidyne complex of the subject invention,
(181) In one embodiment, the subject invention provides a method for synthesizing an unsaturated compound via alkyne cross-metathesis, the method comprising: providing a first substrate and a second substrate, each of the first and second substrate comprising at least one internal alkyne and/or a terminal alkyne; contacting the first and second substrates with a vanadium alkylidyne complex of the subject invention or a composition comprising the vanadium alkylidyne complex of the subject invention, wherein the vanadium alkylidyne complex catalyzes the alkyne cross-metathesis to produce the unsaturated compound comprising an internal alkyne and/or a terminal alkyne resulted from the cross metathesis of the first substrate and the second substrates; and optionally, collecting the unsaturated compound.
(182) In one embodiment, the subject invention provides a method for synthesizing a polymer (e.g., unsaturated polymer) via acyclic diyne metathesis polymerization (ADIMET), the method comprising: providing at least one substrate, the at least one substrate comprising at least one internal alkyne and/or a terminal alkyne; contacting the at least one substrate with a vanadium alkylidyne complex of the subject invention or a composition comprising the vanadium alkylidyne complex of the subject invention, wherein the vanadium alkylidyne complex catalyzes the ADIMET to produce a polymer comprising a plurality of alkynes resulted from the ADIMET of the at least one substrate; and optionally, collecting the polymer.
(183) In certain embodiments, the method for synthesizing a polymer via ADIMET comprises contacting two or more substrates with a vanadium alkylidyne complex of the subject invention or a composition comprising the vanadium alkylidyne complex of the subject invention.
(184) In one embodiment, the subject invention provides a method for synthesizing a polymer (e.g., unsaturated polymer) via ring expansion alkyne metathesis polymerization (REAMP), the method comprising: providing at least one substrate, the at least one substrate comprising at least one internal alkyne and/or a terminal alkyne; contacting the at least one substrate with a vanadium alkylidyne complex of the subject invention or a composition comprising the vanadium alkylidyne complex of the subject invention, wherein the vanadium alkylidyne complex catalyzes the REAMP to produce a polymer comprising a plurality of alkynes resulted from the REAMP of the at least one substrate; and optionally, collecting the polymer.
(185) In certain embodiments, the method for synthesizing a polymer via REAMP comprises contacting two or more substrates with a vanadium alkylidyne complex of the subject invention or a composition comprising the vanadium alkylidyne complex of the subject invention.
(186) In one embodiment, the subject invention provides a method for synthesizing a polymer (e.g., unsaturated polymer) via ring-opening alkyne metathesis polymerization (ROAMP), the method comprising: providing at least one substrate, the at least one substrate comprising at least one internal alkyne and/or a terminal alkyne; contacting the at least one substrate with a vanadium alkylidyne complex of the subject invention or a composition comprising the vanadium alkylidyne complex of the subject invention, wherein the vanadium alkylidyne complex catalyzes the ROAMP to produce a polymer comprising a plurality of alkynes resulted from the ROAMP of the at least one substrate; and optionally, collecting the polymer.
(187) In certain embodiments, the method for synthesizing a polymer via ROAMP comprises contacting two or more substrates with a vanadium alkylidyne complex of the subject invention or a composition comprising the vanadium alkylidyne complex of the subject invention.
(188) In specific embodiment, the subject invention provides a method for synthesizing an unsaturated compound via a metathesis reaction (e.g., olefin metathesis or alkyne metathesis), the method comprising contacting at least one, two or three substrates with the vanadium alkylidyne complex of the subject invention (e.g., vanadium alkylidyne complexes having formula I, II, III, and IV) or the composition comprising the vanadium alkylidyne complex of the subject invention (e.g., vanadium alkylidyne complexes having formula I, II, III, and IV). In specific embodiments, the substrates are selected from olefins and alkynes. The vanadium alkylidyne complex catalyzes a cross-metathesis reaction between the substrates or a polymerization of the at least one, two or three substrates.
(189) Definitions
(190) To facilitate an understanding of the present invention, a number of terms and phrases are defined below. The terminology used herein is used only for the purpose of describing particular embodiments of the present invention and is not intended to be limiting in any way.
(191) As used herein, the singular forms a, an, and the are intended to include the plural forms as well, unless the context clearly indicates otherwise. Furthermore, to the extent that the terms including, includes, having, has, with, or variants thereof are used in either the detailed description and/or the claims, such terms are intended to be inclusive in a manner similar to the term comprising. The transitional terms/phrases (and any grammatical variations thereof) comprising, comprises, and comprise can be used interchangeably; consisting essentially of, and consists essentially of can be used interchangeably; and consisting, and consists can be used interchangeably.
(192) The transitional term comprising, comprises, or comprise is inclusive or open-ended and does not exclude additional, unrecited elements or method steps. By contrast, the transitional phrase consisting of excludes any element, step, or ingredient not specified in the claim. The phrases consisting or consists essentially of indicate that the claim encompasses embodiments containing the specified materials or steps and those that do not materially affect the basic and novel characteristic(s) of the claim. Use of the term comprising contemplates other embodiments that consist or consisting essentially of the recited component(s).
(193) Except in the examples, or where otherwise expressly indicated, all numerical quantities in this description indicating amounts of material and/or use are to be understood as modified by the word about in describing the broadest scope of the invention. Practice within the numerical limits stated is generally preferred.
(194) The term about or approximately means within an acceptable error range for the particular value as determined by one of ordinary skill in the art, which will depend in part on how the value is measured or determined, i.e., the limitations of the measurement system. For example, about can mean within 1 or more than 1 standard deviation, per the practice in the art. Alternatively, about can mean a range of up to 0-20%, 0 to 10%, 0 to 5%, or up to 1% of a given value. Where particular values are described in the application and claims, unless otherwise stated the term about meaning within an acceptable error range for the particular value should be assumed. In the context of compositions containing amounts of concentrations of ingredients where the term about is used, these values include a variation (error range) of 0-10% around the value (X10%).
(195) Ranges are stated in shorthand to avoid having to set out at length and describe each and every value within the range. Any appropriate value within the range can be selected, where appropriate, as the upper value, lower value, or the terminus of the range. For example, a range of 0.1-1.0 represents the terminal values of 0.1 and 1.0, as well as the intermediate values of 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, and all intermediate ranges encompassed within 0.1-1.0, such as 0.2-0.5, 0.2-0.8, 0.7-1.0, etc. Values having at least two significant digits within a range are envisioned, for example, a range of 5-10 indicates all the values between 5.0 and 10.0 as well as between 5.00 and 10.00 including the terminal values. When ranges are used herein, combinations and subcombinations of ranges (e.g., subranges within the disclosed range) and specific embodiments therein are explicitly included.
(196) The term and/or as used herein refers to and encompasses any and all possible combinations of one or more of the associated listed items. For example, the phrase A, B, and/or C includes A alone, B alone, C alone, the combination of A and B, the combination of A and C, the combination of B and C, and the combination of A, B, and C. Also, the term or is used in its inclusive sense (and not in its exclusive sense) so that when used, for example, to connect a list of items, the term or means one, some, or all of the items in the list. Conjunctive language such as the phrase at least one of X, Y, and Z, unless specifically stated otherwise, is otherwise understood with the context as used in general to convey that an item, term, etc. may be either X, Y, or Z; X and Y; X and Z; Y and Z; or X, Y, and Z (i.e., any combination of X, Y, and Z).
(197) As used herein, the term complex or coordinated compound, refers to the result of a donor-acceptor mechanism or Lewis acid-base reaction between a metal (the acceptor) and several neutral molecules or ionic compounds called ligands, each containing a non-metallic atom or ion (the donor).
(198) As used herein, the term monodentate ligand refers to a ligand that has only one atom with lone pairs of electrons (i.e. only one point of attachment to the metal center) and therefore occupies one coordination site; the term polydentate ligand refers to a ligand that has more than one atom with lone pairs of electrons (i.e. more than one point of attachment to the metal center) and therefore occupies more than one coordination site. Depending upon the number of coordination sites occupied, the ligands described herein include monodentate, bidentate, and tridentate ligands.
(199) The term alkene refers to any hydrocarbon that contains one or more carbon-carbon double bonds. Alkene can include straight-chain, branched, and cyclic alkenes (including monocyclic and polycyclic alkenes). Examples include, but are not limited to, ethane, propene, butene, pentene, hexene, heptene, octene, nonene, decene, dodecene, propadiene, butadiene, pentadiene, hexadiene, octadiene, and the like.
(200) The term alkyne refers to any hydrocarbon that contains one or more carbon-carbon triple bonds. Alkyne can include straight-chain, branched, and cyclic alkynes. Those with one triple bond have a general formula of C.sub.nH.sub.2n-2. Examples include, but are not limited to, ethyne, propyne, butyne, pentyne, hexyne, heptyne, octyne, nonyne, decyne, and the like.
(201) As used herein, alkyl refers to saturated monovalent radicals of at least one carbon atom or a branched saturated monovalent of at least three carbon atoms. It can include straight-chain alkyl groups, branched-chain alkyl groups, cycloalkyl (alicyclic) groups, alkyl substituted cycloalkyl groups, and cycloalkyl substituted alkyl groups. It may include hydrocarbon radicals of at least one carbon atom, which may be linear. Examples include, but are not limited to, methyl, ethyl, propyl, 2-propyl, n-butyl, iso-butyl, tert-butyl, pentyl, hexyl, and the like.
(202) As used herein, aryl refers to a carbocyclic (all carbon) monocyclic or multicyclic aromatic ring system (including fused ring systems where two carbocyclic rings share a chemical bond). The number of carbon atoms in an aryl group can vary. For example, the aryl group can be a C.sub.6-C.sub.14 aryl group, a C.sub.6-C.sub.10 aryl group, or a C.sub.6 aryl group. Examples of aryl groups include, but are not limited to, phenyl, benzyl, -naphthyl, -naphthyl, biphenyl, anthryl, tetrahydronaphthyl, fluorenyl, indanyl, biphenylenyl, and acenaphthenyl. Preferred aryl groups are phenyl and naphthyl.
(203) As used herein, halogen refers to an atom of fluorine, chlorine, bromine or iodine.
(204) As used herein, a substituted group may be substituted with one or more group(s) individually and independently selected from, for example, alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl, cycloalkynyl, benzyl, substituted benzyl, aryl, heteroaryl, heteroalicyclyl, aralkyl, heteroaralkyl, (heteroalicyclyl)alkyl, hydroxy, protected hydroxyl, alkoxy, aryloxy, acyl, mercapto, alkylthio, arylthio, cyano, halogen, thiol, thiocarbonyl, O-carbamyl, N-carbamyl, O-thiocarbamyl, N-thiocarbamyl, C-amido, N-amido, S-sulfonamido, N-sulfonamido, C-carboxy, protected C-carboxy, O-carboxy, isocyanato, thiocyanato, isothiocyanato, nitro, silyl, sulfenyl, sulfinyl, sulfonyl, haloalkyl, haloalkoxy, trihalomethanesulfonyl, trihalomethanesulfonamido, an amino, a mono-substituted amino group and a di-substituted amino group, and protected derivatives thereof.
(205) As used herein, the term alcohol is art-recognized and refers to any substance having an OH group attached to a carbon. In certain embodiments, the alcohol is a primary alcohol, a secondary alcohol, or a tertiary alcohol. In some embodiments, the alcohol is a monohydric alcohol or a polyhydric alcohol. In certain embodiments, the alcohol is a diol, triol, tetraol, pentol, or hexol. In one embodiment, the alcohol is an aliphatic alcohol including saturated aliphatic or unsaturated aliphatic alcohol. In some embodiments, the alcohol is an allylic, homoallylic, doubly allylic, doubly homoallylic, propargylic, homopropargylic, doubly propargylic, doubly homopropargylic, benzylic, homobenzylic, doubly benzylic, or doubly homobenzylic alcohol. In certain embodiments, the alcohol is a glycol, a glycerol, an erythritol, a xylitol, a mannitol, an inositol, a menthol or a naturally or non-naturally occurring sugar. In other embodiments, the alcohol is a cycloalkanol, a phenol or other aryl alcohol, or a heteroaryl alcohol. Any of the aforementioned alcohols may be optionally substituted with one or more halogens, alkyls, alkenyls, alkynyls, hydroxyls, aminos, nitros, thiols, amines, imines, amides, phosphonates, phosphines, carbonyls, carboxyls, silyls, ethers, thioethers, sulfonyls, selenoethers, ketones, aldehydes, esters, fluoroalkyls, trifluoromethyl, and cyano groups. Examples include, but are not limited to, methanol, ethanol, isopropyl alcohol, butyl alcohol, isobutyl alcohol, t-butanol, pentanol, pentan-2-ol, pentan-3-ol, hexanol, heptanol, octanol, cyclopentanol, cyclohexanol, benzyl alcohol, 2-phenylethan-1-ol, 2-phenylpropan-2-ol, 5-phenyl-pent-1-ol, 2,2,2-trifluoroethan-1-ol, 2-methoxyethan-1-ol and the like.
(206) Throughout this application, where publications are referenced, the disclosures of these publications in their entireties are hereby referred to in this application to more fully describe the state of the art to which this invention pertains.
(207) Abbreviations used herein include: V, vanadium; NBO, natural bond orbital; NHC, N-heterocyclic carbene; iPr, isopropyl; THF, tetrahydrofuran; TMS, trimethylsilyl group.
(208) Unless otherwise defined, all terms of art, notations and other scientific terms or terminology used herein are intended to have the meanings commonly understood by those of skill in the art to which this invention pertains. In some cases, terms with commonly understood meanings are defined herein for clarity and/or for ready reference, and the inclusion of such definitions herein should not necessarily be construed to represent a substantial difference over what is generally understood in the art. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and/or as otherwise defined herein.
EXAMPLES
Materials and Methods
General Experimental Details
(209) All reactions involving air and moisture-sensitive materials were performed in a nitrogen-filled MBraun glovebox or otherwise in a Schlenk line. All glassware was oven-dried prior to use (160 C.). Solvents used, such as diethyl ether (Et.sub.2O), n-hexane, pentane, etc., were dried using the Na/benzophenone system and stored in the glovebox under an inert atmosphere over 3 A molecular sieves (which were also oven-dried beforehand). C.sub.6D.sub.6 was stored in the glovebox under 3 molecular sieves as well. NMR spectra were obtained on Bruker 400 MHz and 600 MHz spectrometers. Chemical shifts for .sup.1H and .sup.13C spectra are reported in parts per million (ppm) and use the residual .sup.1H and .sup.13C resonances of the deuterated solvent as reference (.sup.1H S: CD.sub.2Cl.sub.2 5.32, C.sub.6D.sub.6 7.16, .sup.13C : CD.sub.2Cl.sub.2 53.84, C.sub.6D.sub.6 128.06). All NMR data shown have the following format: chemical shift, multiplicity (s=singlet, d=doublet, t=triplet, m=multiplet, br=broad), coupling constants (Hz), and integration.
Starting Materials
(210) Reagents were purchased at the highest commercial quality and utilized without further purification unless otherwise stated. Vanadium(V) oxytriisopropoxide (97.0%+), (Trimethylsilyl) methyl magnesium chloride (1.00 M solution in Et.sub.2O), triphenylchlorosilane (95%+), triphenylsilanol (95%+), and phenyldimethylchlorosilane (96%+) were purchased from TCI America. 4,4-di-tert-butyl-2,2-bipyridine (dtbbpy) (98.0%+) was purchased from Sigma Aldrich. Lithium bis(trimethylsilyl)amide (LiN(TMS).sub.2, 95%+) and chloro(methyl) diphenylsilane (97%+) were purchased from Thermo Scientific Chemicals.
Vanadium(V) oxytriisopropoxide
(211) ##STR00035##
(212) Vanadium(V) oxytriisopropoxide is commercially available, whose spectra is provided as:
(213) .sup.1H NMR: (C.sub.6D.sub.6, 400 MHz) 5.11 (sept, 3H, J=6.4 Hz), 1.33 (d, 18H, J=6.4 Hz).
(214) .sup.51V NMR: (C.sub.6D.sub.6, 105 MHz) 630 ppm.
Synthesis of Vanadium Alkylidene Complexes
VO(CH.SUB.2.TMS).SUB.3 .(1)
(215) Inside the glovebox, vanadium(V) oxytriisopropoxide (7.84 g, 32.10 mmol, 1 equiv.) was placed in a Schlenk flask. The flask was sealed with a septum, taken out from the glovebox, and connected to the Schlenk line via a hose. The hose was connected to a vacuum for one minute and then to nitrogen. The procedure was repeated twice (three times total) to ensure there was no air between the Schlenk line and the Schlenk flask in the hose. The Schlenk flask's valve was opened to nitrogen. The septum was removed, and 400 ml of pentane was added (HPLC grade pentane; no additional purification was used). The flask was sealed with a septum. The flask was immersed in an acetone/dry ice bath. The reaction mixture was stirred in the cooling bath for 10 minutes to ensure the reaction mixture (RM) was cooled down. During that time, RM remained colorless. Solution of TMSCH.sub.2MgCl in Et.sub.2O (1.0 M, 73.8 ml, 73.82 mmol, 2.3 equiv.) was slowly added dropwise to the stirred solution via syringe at 78 C. RM becomes red-brown during this time. RM was stirred for 30 minutes in an acetone/dry ice bath. The cooling bath was removed, and RM was stirred at room temperature for 30 minutes. A white precipitate formed (Mg salts) during warming up, while the RM became a yellow-green suspension. The flask was transferred to the glovebox. The precipitate was filtered off with celite and washed with pentane until the precipitate (Mg salts) became an off-white solid. The yellow-green pentane solution was connected to a vacuum to remove pentane and produce a yellow-green solid. The green solid was dissolved in the minimal amount of Et.sub.2O and placed in the freezer at 35 C. to recrystallize. After overnight the yellow crystals were filtered off and dried under vacuum (
(216) .sup.1H NMR: (C.sub.6D.sub.6, 400 MHz) 1.71-1.92 (br. s, 6H), 0.17 (s, 27H).
(217) .sup.51V NMR: (C.sub.6D.sub.6, 105 MHz) 483 ppm.
VOLi(dtbbpy)(CHSiMe.SUB.3.)(CH.SUB.2.SiMe.SUB.3.).SUB.2 .(2.Math.dtbbpy)
(218) 4,4-di-tert-butyl-2,2-bipyridine (dtbbpy) (1.94 g, 7.24 mmol, 1.0 equiv.) was dissolved in 58 mL of Et.sub.2O to form a clear, colorless solution. A solution of LiN(TMS).sub.2 (1.33 g, 7.96 mmol, 1.1 equiv.) in n-hexane (58 mL) was added to solid complex 1 (2.38 g, 7.24 mmol, 1.0 equiv.) under stirring to generate an anionic alkylidene complex 2, upon addition the solution changed from yellow to dark green. The solution of the dtbbpy in ether was then added to the solution of the anionic alkylidene complex 2. The reaction was allowed to stir for 10-15 min. at RT, during which the solution changed from dark green to dark blue. Upon completion, the solvents were removed, and the dark blue residue that formed was washed with n-hexane, filtered, dried, and placed into the glovebox freezer as a lavender powder (
(219) .sup.1H NMR: (C.sub.6D.sub.6, 400 MHz) 15.73 (s, 2H), 9.30 (d, J=5.3 Hz, 4H), 8.04 (d, J=1.5 Hz, 4H), 7.21 (dd, J=5.3, 1.7 Hz, 4H), 1.11 (s, 36H), 0.39 (d, J=11.0 Hz, 4H), 0.24 (s, 18H), 0.17 (s, 36H), 0.09 (d, J=10.3 Hz, 4H).
(220) .sup.13C NMR (C.sub.6D.sub.6, 101 MHz) 343.1, 171.0, 161.6, 156.3, 121.0, 115.1, 29.7, 13.6, 7.8, 26.1, 26.6.
(221) .sup.51V NMR: (C.sub.6D.sub.6, 105 MHz) 883.8 ppm.
(222) Anal. Calcd for C.sub.60H.sub.112Li.sub.2N.sub.4O.sub.2Si.sub.6V.sub.2: C, 59.76%; H, 9.36%; N, 4.65%. Found: C, 58.28%; H, 8.50%; N, 4.67%.
General Procedure for 6a-c
(223) Complex 2.Math.dtbbpy (0.754 g, 1.25 mmol, 1.0 equiv.) was dissolved in 7.5 mL Et.sub.2O and cooled to 35 C. for 30 minutes before the corresponding chlorosilane (1.25 mmol, 1.0 equiv.) was added slowly. The reaction mixture was allowed to stir for 10-15 min., during which the solution changed from dark blue to brown, before being filtered to another container (to remove the LiCl that forms). The Et.sub.2O was evaporated, and the resulting brown residue was washed with n-hexane, filtered, and dried under a vacuum. The alkylidyne products appear as brown powder-like solids (
V(CSiMe.SUB.3.)(dtbbpy)(CH.SUB.2.SiMe.SUB.3.)(OSiPhMe.SUB.2.) (6a)
(224) ##STR00036##
(225) Purification of 6a can be conducted via various means, such as washing with pentane. M=0.650 g (81%).
(226) .sup.1H NMR: (C.sub.6D.sub.6, 400 MHz) 9.96 (d, J=5.8 Hz, 2H), 8.40 (d, J=7.2 Hz, 2H), 7.60 (d, J=1.3 Hz, 2H), 7.47 (t, J=7.4 Hz, 3H), 7.35 (dd, J=9.4, 5.2 Hz, 1H), 6.74 (d, J=4.8 Hz, 2H), 2.97 (d, J=13.2 Hz, 1H), 1.22 (s, 3H), 1.07 (d, J=13.2 Hz, 1H), 1.05 (s, 3H), 0.92 (s, 18H), 0.14 (s, 9H), 0.01 (s, 9H).
(227) .sup.13C NMR: (C.sub.6D.sub.6, 151 MHz) 417.2, 163.2, 153.3, 152.4, 145.2, 134.7, 128.7, 128.3, 121.6, 117.0, 46.2, 34.9, 30.1, 3.6, 3.2, 3.0, 1.4.
(228) .sup.51V NMR: (C.sub.6D.sub.6, 105 MHz) 573.5.
(229) Anal. Calcd for C.sub.34H.sub.55N.sub.2OSi.sub.3V: C, 63.51%; H, 8.62%; N, 4.36%. Found: C, 60.16%; H, 8.16%; N, 3.72%.
V(CSiMe.SUB.3.)(dtbbpy)(CH.SUB.2.SiMe.SUB.3.)(OSiPh.SUB.2.Me) (6b)
(230) ##STR00037##
(231) Recrystallized from n-hexane at 35 C. M=0.606 g (69%).
(232) .sup.1H NMR: (C.sub.6D.sub.6, 600 MHz) 9.95 (d, J=5.2 Hz, 2H), 8.47 (d, J=7.2 Hz, 2H), 8.29 (d, J=7.2 Hz, 2H), 7.61 (s, 2H), 7.43 (t, J=7.3 Hz, 2H), 7.40 (t, J=7.3 Hz, 2H), 7.34-7.28 (m, 2H), 6.74 (s, 2H), 3.02 (d, J=13.1 Hz, 1H), 1.35 (s, 3H), 0.99 (d, J=13.1 Hz, 1H), 0.93 (s, 18H), 0.09 (s, 9H), 0.06 (s, 9H).
(233) .sup.13C NMR: (C.sub.6D.sub.6, 151 MHz) 419.3, 163.3, 153.4, 152.4, 143.1, 142.7, 135.8, 135.5, 128.9, 128.3, 128.0, 121.6, 117.1, 48.3, 34.9, 30.1, 2.9, 2.2, 1.3.
(234) .sup.51V NMR: (C.sub.6D.sub.6, 105 MHz) 590.0.
(235) Anal. Calcd for C.sub.39H.sub.57N.sub.2OSi.sub.3V: C, 66.43%; H, 8.15%; N, 3.97%. Found: C, 65.25%; H, 8.10%; N, 3.86%.
V(CSiMe.SUB.3.)(dtbbpy)(CH.SUB.2.SiMe.SUB.3.)(OSiPh.SUB.3.) (6c)
(236) ##STR00038##
(237) Recrystallized from Et.sub.2O at 35 C. M=0.805 g (84%).
(238) .sup.1H NMR: (CD.sub.2Cl.sub.2, 400 MHz) 9.78 (d, J=5.8 Hz, 2H), 8.15 (s, 2H), 7.98 (d, J=7.1 Hz, 6H), 7.40 (dd, J=13.0, 6.7 Hz, 9H), 2.58 (d, J=12.8 Hz, 1H), 1.48 (s, 1811), 0.30 (d, J=12.7 Hz, 1H), 0.42 (s, 9H), 0.56 (s, 9H).
(239) .sup.13C NMR: (CD.sub.2Cl.sub.2, 101 MHz) 421.0, 163.8, 152.8, 152.1, 140.0, 135.9, 128.6, 127.2, 121.3, 117.6, 49.1, 35.2, 30.1, 1.8, 0.1.
(240) .sup.51V NMR: (CD.sub.2Cl.sub.2, 105 MHz) 617.0.
(241) Anal. Calcd for C.sub.44H.sub.59N.sub.2OSi.sub.3V: C, 68.89%; H, 7.75%; N, 3.65%. Found: C, 68.38%; H, 7.77%; N, 3.70%.
VOLi(CHSiMe.SUB.3.)(CH.SUB.2.SiMe.SUB.3.).SUB.2 .(2)
(242) A solution of LiHMDS (14 mg, 0.084 mmol, 1.1 equiv.) in 0.6 ml of C.sub.6D.sub.6 was added to stirred solid complex 1 (25 mg, 0.076 mmol, 1.0 equiv.) to generate the anionic alkylidene complex 2 in situ. Upon mixing, the solution changed from colorless to dark green. The reaction scheme is shown in
(243) .sup.1H NMR: (C.sub.6D.sub.6, 400 MHz) 15.07 (s, 1H), 1.49 (d, J=10.6 Hz, 2H), 0.85 (d, J=10.6 Hz, 2H), 0.41 (s, 9H), 0.29 (s, 19H).
(244) .sup.13C NMR: (C.sub.6D.sub.6, 151 MHz) 303.9, 62.9, 2.6, 0.1.
(245) Base Screening
(246) Complex 1 (25 mg, 0.076 mmol, 1.0 equiv.) was mixed with a base (0.084 mmol, 1.1 equiv.) in 0.6 ml of C.sub.6D.sub.6. The resulting mixture was analyzed by .sup.1H NMR. 1. LiHMDS gives a clean conversion to 2. 2. KHMDS leads to the formation of alkylidene, but peaks broadening was observed, suggesting the formation of paramagnetic species. 3. TMSCH.sub.2Li leads to the formation of alkylidene, but peaks broadening was observed, suggesting the formation of paramagnetic species. 4. t-BuOK leads to the formation of alkylidene; however, the reaction of alkylidene with t-BuOH causes the slow decomposition of alkylidene to occur over a few hours. 5. Ph.sub.3SiOKno reaction. 6. NaHdecomposition.
The Reaction Between 2 and Ph.sub.3SiOH
(247) A solution of LiHMDS (14 mg, 0.084 mmol, 1.1 equiv.) in 0.6 ml of C.sub.6D.sub.6 was added to stirred solid complex 1 (25 mg, 0.076 mmol, 1.0 equiv.) to generate the anionic alkylidene complex 2 in situ. The reaction was stirred at room temperature for 1 hour before the solid Ph.sub.3SiOH (23.13 mg, 0.084 mmol, 1.1 equiv.) was added all at once, which turned the solution from dark green to brown. The reaction scheme and the reaction between complex 2 and Ph.sub.3SiOH are shown in
(248) The Reaction Between 2 and Ph.sub.2MeSiCl
(249) A solution of LiHMDS (14 mg, 0.084 mmol, 1.1 equiv.) in 0.6 ml of C.sub.6D.sub.6 was added to stirred solid complex 1 (25 mg, 0.076 mmol, 1.0 equiv.) to generate the anionic alkylidene complex 2 in situ. The reaction was stirred at room temperature for 1 hour before Ph.sub.2MeSiCl (19.48 mg, 0.084 mmol, 1.1 equiv.) was added dropwise. .sup.1H NMR was taken after 1 hour at room temperature. The reaction scheme and the reaction between complex 2 and Ph.sub.2MeSiCl are shown in
(250) DOSY NMR Experiment
(251) DOSY experiment was performed in the presence of 1,3,5-tert-butylbenezene (
(252) TABLE-US-00001 TABLE 1 DOSY NMR experiment. Chemical logD MW MW Compound shifts, ppm [m2/s] D calc. actual Complex 2 15.07, 1.49, 9.25 5.62e10 907.3 0.85, 0.41, 0.29 1,3,5-tert- 7.38, 1.35 8.90 12.59e10 168.5 246.4 butylbenezene
(253) MW was calculated using SEGWE software. DOSY experiment suggests that compound 2 forms oligomers in the C.sub.6D.sub.6 at 298K.
(254) NBO Calculations
(255) Geometry was optimized at the b97X-D level of density functional theory with the 6-31G* basis set. Then, the natural bond orbital (NBO) analysis was carried out at the b97X-D/cc-pVTZ level of theory to determine natural bond orders for chemical bonds (Table 2B and
(256) TABLE-US-00002 TABLE 2A NBO calculations of natural charges. atom charge V +1.15 O 0.88 Li +0.91 C (from VC) 1.08 C (from VC) 1.35 Si (from VCSi) +1.79 Si (from VCSi) +1.85, +1.86 N 0.52, 0.53
(257) TABLE-US-00003 TABLE 2B NBO calculations of bond orders. bond order VO 0.99 VC 1.91 VC 0.96, 0.97
X-Ray Structures
2.Math.dtbbpy
(258) C.sub.60H.sub.110Li.sub.2N.sub.4O.sub.2Si.sub.6V.sub.2, crystallizes in the triclinic space group P1_ with a=13.09416(15), b=15.8002(2), c=18.3952(2), =101.0189(8), =99.5205(9), =90.9343(9), V3679.66(8).sub.3, Z=2, and d.sub.calc=1.087 g/cm3. X-ray intensity data were collected on a Rigaku XtaLAB Synergy-S HPC area detector (HyPix-6000HE), employing confocal multilayer optic-monochromated Mo-K radiation (=0.71073 ) at a temperature of 100K. Preliminary indexing was performed from a series of thirty 0.50 rotation frames with exposures of 1.5 seconds. A total of 1844 frames (12 runs) were collected employing scans with a crystal to detector distance of 34.0 mm, rotation widths of 0.5 and exposures of 5 seconds.
(259) Rotation frames were integrated using CrysAlisPro, producing a listing of unaveraged F2 and (F2) values. A total of 111986 reflections were measured over the ranges 3.568256.564, 17h17, 21k21, 24124 yielding 18275 unique reflections (Rint=0.0315). The intensity data were corrected for Lorentz and polarization effects and for absorption using SCALE3 ABSPACK (minimum and maximum transmission 0.8831, 1.0000). The structure was solved by direct methods SHELXT. There are two molecules in the unit cell, both lying on crystallographic centers-of-symmetry (at , , and , 0, 0). The t-Butyl group C15-C16-C17-C18 was rotationally disordered with relative occupancies of 0.65/0.35. Refinement was by full-matrix least squares based on F2 using SHELXL-2018. All reflections were used during refinement. The weighting scheme used was w=1/[.sup.2(Fo.sup.2)+(0.0440P).sup.2+1.3232P] where P=(Fo.sup.2+2F.sub.c.sup.2)/3. Non-hydrogen atoms were refined anisotropically and hydrogen atoms were refined using a riding model. Refinement converged to R1=0.0311 and wR2=0.0847 for 16153 observed reflections for which F>4(F) and R1=0.0361 and wR2=0.0871 and GOF=1.052 for all 18275 unique, non-zero reflections and 739 variables. The maximum / in the final cycle of least squares was 0.001 and the two most prominent peaks in the final difference Fourier were +0.84 and 0.43 e/.sup.3.
(260) Tables 3A-3D list cell information, data collection parameters, and refinement data. The crystal structures are shown in
(261) TABLE-US-00004 TABLE 3A Crystal Data for complex 2dtbbpy. Crystal data F(000) = 1300 Chemical formula C.sub.60H.sub.110Li.sub.2N.sub.4O.sub.2Si.sub.6V.sub.2 M.sub.r 1203.81 Crystal system, Triclinic, P1 space group Temperature (K.) 100 a, b, c () 13.09416(15), 15.8002 (2), 18.3952 (2) () 101.0189 (8) () 99.5205 (9) 90.9343 (9) V (.sup.3) 3679.66 (8) Z 2 Radiation type Mo K (mm.sup.1) 0.39 Crystal size (mm) 0.25 0.18 0.18 2 range for 3.568 56.564 data collection Index ranges 17 h 17, 21 k 21, 24 1 24 Reflections collected 111986 Independent reflections 18275[R(int) = 0.0315] Data/restraints/parameters 18275/19/739 Goodness-of-fit on F.sup.2 1.052 Final R indexes R.sub.1 = 0.0311, wR.sub.2 = 0.0847 [I >= 2 (I)] Final R indexes [all data] R.sub.1 = 0.0361, wR.sub.2 = 0.0871 Largest diff. peak/hole 0.84/0.43 e.sup.3
(262) TABLE-US-00005 TABLE 3B Crystal Data for complex 6b. Crystal data F(000) = 3032 Chemical formula C.sub.39H.sub.58N.sub.2OSi.sub.3V M.sub.r 706.08 Crystal system, space group Monoclinic, P1.sub.2/a Temperature (K.) 273.15 a, b, c () 26.032 (4), 11.5481 (17), 30.838 (5) () 90 () 103. 169 (15) () 90 V (.sup.3) 9027 (2) Z 8 .sub.calc 1.039 Radiation type Mo K ( = 0.71073) (mm.sup.1) 0.327 Crystal size (mm) 0.2 0.15 0.1 Data collection Diffractometer Bruker D8 Quest PHOTON II Absorption correction Multi-scan 2 range for data collection/ 4.756 to 50.41 Index ranges 31 h 31, 13 k 13, 36 1 36 Reflections collected 24107 Independent reflections 8049 [R.sub.int = 0.2624, R.sub.sigma = 0.3055] Data/restraints/parameters 8049/18/428 Goodness-of-fit on F.sup.2 1.019 Final R indexes [I >= 2 (I)] R.sub.1 = 0.1417, wR.sub.2 = 0.2940 Final R indexes [all data] R.sub.1 = 0.2801, wR.sub.2 = 0.3656 Largest diff. peak/hole/e .sup.3 0.56/0.55
Computing Details
(263) Data collection: Bruker APEX3; cell refinement: SAINT V8.401B; data reduction: SAINT V8.401B; program(s) used to solve structure: SHELXT 2018/2; program(s) used to refine structure: XL; molecular graphics: Olex2 1.3; software used to prepare material for publication: Olex2 1.3.
V(CSiMe.SUB.3.)(dtbbpy)(CH.SUB.2.SiMe.SUB.3.)(OSiPh.SUB.3.) (6c)
(264) TABLE-US-00006 TABLE 3C Crystal Data for complex 6c. Crystal data Chemical formula C.sub.44H.sub.59N.sub.2OSi.sub.3V M.sub.r 767.14 Crystal system, space group P2.sub.1/c Temperature (K.) 170 a, b, c () 11.130 (4), 29.284 (11), 13.734 (5) () 100.816 (6) V (.sup.3) 4397 (3) Z 4 Radiation type Mo K (mm.sup.1) 0.34 Crystal size (mm) 0.10 0.06 0.04 Data collection Diffractometer Bruker D8 Quest PHOTON II Absorption correction Multi-scan SADABS2016/2 (Bruker, 2016/2) was used for absorption correction. wR2(int) was 0.1008 before and 0.0769 after correction. The Ratio of minimum to maximum transmission is 0.6690. The /2 correction factor is Not present. T.sub.min, T.sub.max 0.499, 0.745 No. of measured, 31181, 7540, 4846 independent and observed [I > 2(I)] reflections R.sub.int 0.084 (sin 0/)max (.sup.1) 0.590 Refinement R[F.sup.2 > 2(F.sup.2)], wR(F.sup.2), S 0.077, 0.215, 1.09 No. of reflections 7540 No. of parameters 472 H-atom treatment H-atom parameters constrained w = 1/[.sup.2(F.sub.o.sup.2) + (0.0688P).sup.2 + 10.3264P] where P = (F.sub.o.sup.2 + 2F.sub.c.sup.2)/3 max, min (e A.sup.3) 0.67, 0.41
(265) Computer programs: Bruker Apex3, SAINT V8.401B, SHELXT 2018/2, XL, Olex2 1.3.
(266) Computing Details
(267) Data collection: Bruker APEX3; cell refinement: SAINT V8.401B; data reduction: SAINT V8.401B; program(s) used to solve structure: SHELXT 2018/2; program(s) used to refine structure: XL; molecular graphics: Olex2 1.3; software used to prepare material for publication: Olex2 1.3.
(268) TABLE-US-00007 TABLE 3D Crystal Data for complex 6c. Crystal data C.sub.44H.sub.59N.sub.2OSi.sub.3V F(000) = 1640 M.sub.r = 767.14 Dx = 1.159 Mg m.sup.3 Monoclinic, P2.sub.1/c Mo K radiation, = 0.71073 a = 11.130 (4) Cell parameters from 8127 reflections b = 29.284 (11) = 2.6-24.0 c = 13.734 (5) = 0.34 mm.sup.1 = 100.816 (6) T = 170K V = 4397 (3) .sup.3 Plate, brown Z = 4 0.10 0.06 0.04 mm Data collection Bruker D8 Quest PHOTON II T.sub.min = 0.499, T.sub.max = 0.745 Diffractometer 31181 measured reflections scans 7540 independent reflections Absorption correction: 4846 reflections with I > 2(I) multi-scan SADABS2016/2 R.sub.int = 0.084 (Bruker, 2016/2) was used .sup.max = 24.8, .sub.min = 2.3 for absorption correction. h = 13.fwdarw.13 wR2(int) was 0.0740 before k = 34.fwdarw.34 and 0.0769 after correction. l = 15.fwdarw.16 The Ratio of minimum to maximum transmission is 0.6690. The /2 correction factor is Not present. Refinement Refinement on F.sup.2 Secondary atom site location: diffmap Least-squares matrix: full Hydrogen site location: inferred from neighboring sites R[F.sup.2 > 2(F.sup.2)] = 0.033 H-atom parameters constrained wR(F.sup.2) = 0.097 w = 1/[.sup.2(F.sub.o.sup.2) + (0.0688P).sup.2 + 10.3264P] S = 1.07 where P = (F.sub.o.sup.2 + 2F.sub.c.sup.2)/3 7540 reflections (/)max < 0.001 472 parameters .sub.max = 0.67 e .sup.3 0 restraints .sub.min = 0.41 e .sup.3 Primary atom site location: dual
Special Details
(269) Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes.
Example 1Synthesis of Alkylidyne Complexes
(270) The examples provided herein exemplarily describe the development of a series of V oxo alkylidenes, a new class of compounds that exhibit unique reactivity in olefin metathesis. The key starting material for the synthesis of those catalysts is VO(CH.sub.2TMS).sub.3 (complex 1). Complex 1 was made from the oxidation reaction between V(CH.sub.2TMS).sub.3-THF and styrene oxide. The reaction was challenging and suffered from scalability and reproducibility. To improve the synthesis of complex 1, several reaction conditions and reagents were screened, including commercially available V(+5) oxo complexes and alkylating agents (TMSCH.sub.2Li, TMSCH.sub.2MgCl, (TMSCH.sub.2).sub.2Zn, and (TMSCH.sub.2).sub.3Al).
(271) The key finding is the use of 2.3 equiv of TMSCH.sub.2MgCl (instead of 3.0 equiv) and VO(O.sup.iPr).sub.3 at 78 C. to avoid the reduction of V species, which can be easily seen by the appearance of a green color during the reaction.
(272) During the screening of optimal conditions, a new peak was observed in the alkylidene region by .sup.1H NMR in the reactions in which an excess of alkylating agents was used. In separate experiments, it was found that complex 1 reacts with strong bases, including MN(TMS).sub.2 (M=Li or K), or organolithium reagents (RLi), to form the V anionic alkylidene 2 (
(273) The intermolecular -hydrogen abstraction to form alkylidenes from metal alkyl complexes is unusual as there are no reported instances of anionic alkylidenes forming from metal oxo alkyl species. This transformation is exciting by itself from a fundamental standpoint and can provide some crucial insights about the classical intramolecular -hydrogen abstraction reaction.
(274) Complexes 2 (as Li or K salts) are stable and isolable but not crystalline. DOSY NMR experiment suggests that complex 2 (Li salt) forms oligomers in benzene solution. The crystalline Li salt of complex 2 was isolated as a 4,4-bis(tert-butyl)-2,2-bipyridine complex (2-dtbbpy) in 88% isolated yield (
(275) The X-ray structure of 2-dtbbpy revealed a dimer with bridged Li cations with a slightly distorted tetrahedral geometry at the V center. The comparison of structure details of 2-dtbbpy to the known four-coordinate tetrahedral V oxo alkylidene 3 confirmed the presence of one alkylidene and two alkyl groups (
(276) NBO calculations further support the structure of 2.Math.dtbbpy. Thus, the computed VO bond order is 0.99, with charges on the vanadium and oxygen atoms of +1.15 and 0.88, respectively (
(277) The resulting complex resembles a simple carbon-based enolate anion and might react with electrophiles, for example, with silyl chlorides, to provide siloxide complexes in analogy to the formation of enol silyl ethers, taking advantage of the strength of the SiO bond. Indeed, complexes 2 (as a Li or K salt) slowly react with silyl chlorides to form new alkylidenes by .sup.1H NMR that are assigned as V alkylidene siloxide complexes (
(278) The reaction between 2-dtbbpy and silyl chlorides provides V alkylidyne complexes 6a-c (
(279) Complexes 6b (
(280) The presented method is a rare example of converting an oxo ligand at V to a vanadium oxygen single bond (VO to VOR). From a fundamental standpoint, the illustrated transformation is an elegant strategy to convert early transition metal oxo alkyl complexes to siloxide alkylidynes.
(281) The present invention provides a new synthetic pathway to produce d.sup.0 V alkylidynes, an underdeveloped class of 3d Schrock carbynes. In a preferred embodiment, the process involves creating an anionic V alkylidene complex that contains a nucleophilic oxygen atom, making it reactive toward electrophiles such as silyl chlorides. Subsequent -hydrogen abstraction from the alkylidene results in the formation of alkylidynes. The reactivity of the obtained complexes, for example, in alkyne metathesis, is further investigated.
Example 2Reactivity Studies
(282) Evidence of the Cycloaddition Step
(283) Further reactivity studies showed that the prepared V alkylidynes readily react with various internal alkynes to form MCBD complexes and free dtbbpy (
(284) DFT (Density Functional Theory) Studies
(285) To probe the feasibility of the V-based alkyne metathesis, DFT studies of cycloaddition and cycloreversion steps with complex 6c were performed. The dissociation of dtbbpy to form 3-coordinate 8a is highly unfavorable (
(286) In this case, the reaction takes a few hours to complete at room temperature or within one hour under heating at 50 C. This finding highlights the difference between classical alkyne metathesis systems and V reactivity. Thus, the Schrock catalysts are 4-coordinate alkylidynes that form 5-coordinate MCBDs. It is believed that the cycloaddition reaction via associative pathway results from the high electrophilicity of the V atom, which is confirmed spectroscopically. Thus, the .sup.13C NMR chemical shift of the alkylidyne carbon is a valuable tool to access the electrophilicity of the metal center. The alkylidyne carbon in complex 6c has a chemical shift of 421 ppm, significantly higher than the corresponding chemical shift in typical Mo-based catalysts (300 ppm).
(287) The coordination of alkyne followed by the cycloaddition step proceeds trans to stronger -donor ligand (alkyl group in 6c and 9a), which aligns well with the known data. The dissociation of bipyridine ligand leads to thermodynamically favorable 10a, which corresponds with the experiments. The direct cycloreversion from 10a to form 8b is uphill. Therefore, the binding of bipyridine or other neutral ligands is necessary for the efficient cycloreversion step. However, in the case of 10a, the energy barrier to form 6c is 38.4 kcal/mol, which would require substantial heating. Unfortunately, observed V MCBDs decompose above 80 C. Alternatively, the use of strongly donating neural ligands is required to lower the energy barrier of the cycloreversion step.
(288) The ground state of the MCBD isomer 10b was also calculated (
(289) The influence of the anionic ligand at V on the stability of MCBD was explored. The result shows that the substitution of the alkyl group in 10b with siloxide and phenoxide ligands increases the energy of MCBD (
(290) Evidence of the Cycloreversion Step
(291) Complex 6c reacts with silanols, phenols, and thiophenols in Et.sub.2O at RT to form complexes 11 (
(292) The reactivity of the complexes 11 with internal alkynes was explored. Complexes 11a, 11c, and 11e reacted with PhCCMe at 50 C. to form corresponding MCBDs. Interestingly, complex lid does not react with PhCCMe even at 80 C. (lid decomposes above 80 C.). This observation supports the associative pathway. Thus, the bulky 2,6-(MeO).sub.2C.sub.6H.sub.3O ligand might prevent the coordination of the alkyne to the V center, which is crucial to initiate the cycloaddition step.
(293) The formation of only one isomer of MCBD in all three cases (13a, 13c, and 13e) and free bipyridine ligand were observed by .sup.1H NMR. It was observed that 13c showed evidence of the cycloreversion step. Thus, heating the reaction mixture led to the formation of Me.sub.3SiCCMe, which was detected by .sup.1H and .sup.13C NMR. The observed transformation is the first reported alkyne metathesis with a first-row metal. The MeO-group in the ortho position of the phenoxide ligand might play a role in the cycloreversion step by binding to the V center in complex 13c. To reproduce the cycloreversion reaction, 6c was reacted with p-MeOC.sub.6H.sub.4CCMe, which led to the formation of Me.sub.3SiCCMe.
(294) Based on the reactivity studies, it can be concluded: 1. The cycloreversion step requires the formation of a five- or six-coordinated MCBD. It is believed that the coordination of strongly donating ligands is necessary for following alkyne dissociation for two reasons: 1) to lower electrophilicity (Lewis acidity) of the V metal center; 2) to increase a steric bulk around V. Therefore, coordination of a neutral (or anionic) ligand to 13 is preferred for the alkyne metathesis reactions. 2. The electronic properties of the anionic ligand are essential for the efficient cycloreversion step. Thus, it is believed that the -donating anionic ligands are necessary to destabilize the MCBD 13, that is confirmed by DFT and experimentally. The -donating abilities decrease in the row o-MeOC.sub.6H.sub.4O>Ph.sub.3SiO>o-MeOC.sub.6H.sub.4S (LDP=12.14, 13.28, and 14.22, respectively), explaining why the cycloreversion reaction only in the case of o-MeOC.sub.6H.sub.4O (13c) was observed. 3. The steric properties of the ligands are important for the cycloaddition step, which proceeds via an associative pathway. The use of bulky 2,6-(MeO).sub.2C.sub.6H.sub.30 ligand prevents the coordination of the alkyne for the efficient cycloaddition reaction.
(295) All patents, patent applications, provisional applications, and publications referred to or cited herein are incorporated by reference in their entirety, including all figures and tables, to the extent they are not inconsistent with the explicit teachings of this specification.
(296) It should be understood that the examples and embodiments described herein are for illustrative purposes only and that various modifications or changes in light thereof will be suggested to persons skilled in the art and are to be included within the spirit and purview of this application and the scope of the appended claims. These examples should not be construed as limiting. In addition, any elements or limitations of any invention or embodiment thereof disclosed herein can be combined with any and/or all other elements or limitations (individually or in any combination) or any other invention or embodiment thereof disclosed herein, and all such combinations are contemplated within the scope of the invention without limitation thereto.