PROCESS FOR DEHYDROGENATION OF ALKYL-CONTAINING COMPOUNDS USING MOLYBDENUM AND TUNGSTEN NITROSYL COMPLEXES

Abstract

A process for the dehydrogenation of alkyl-containing compounds comprises reacting an alkyl-containing compound and a Group VI nitrosyl complex characterized as a transition metal complex having the composition Cp′M(NO)(R1)(R2), wherein Cp′ is selected from certain substituted and unsubstituted η.sup.5-cyclopentadienyl groups; M is W or Mo; and R1 and R2 are independently selected from CH.sub.2C(CH.sub.3).sub.3; CH.sub.2Si(CH.sub.3).sub.3; CH.sub.2(C.sub.6H.sub.5); CH.sub.3; hydrogen; and η.sup.3-allyl; provided that if R1 is hydrogen, R2 is η.sup.3-allyl; under conditions such that the alkyl-containing compound is converted to an olefin, and in particular embodiments, a terminal olefin. The dehydrogenation can be carried out using a neat and/or undried alkyl-containing compound and/or may be conducted under air, and does not require a sacrificial olefin to drive the reaction, thereby increasing convenience and decreasing cost in comparison with some other dehydrogenation processes.

Claims

1. A process for a dehydrogenation, comprising: reacting an alkyl-containing compound and a transition metal complex having the composition
Cp′M(NO)(R1)(R2) wherein Cp′ is a substituted or unsubstituted η.sup.5-cyclopentadienyl group, wherein the substituents are independently selected from hydrogen and moieties containing from 1 to 40 non-hydrogen atoms selected from hydrocarbyl, arylalkyl, hydrocarbylsilyl, halo-substituted hydrocarbyl, hydrocarbyloxy-substituted hydrocarbyl, hydrocarbylamino-substituted hydrocarbyl, hydrocarbylsilyl-substituted hydrocarbyl, hydrocarbylamino, di(hydrocarbyl)amino, and hydrocarbyloxy moieties, and combinations thereof; and wherein M is selected from W and Mo; and wherein R1 and R2 are each independently selected from (a) CH.sub.2C(CH.sub.3).sub.3; (b) CH.sub.2Si(CH.sub.3).sub.3; (c) CH.sub.2(C.sub.6H.sub.5); (d) CH.sub.3; (e) hydrogen; and (f) η.sup.3-allyl; provided that if R1 is hydrogen, R2 is η.sup.3-allyl; under conditions such that the alkyl-containing compound is converted to an olefin.

2. The process of claim 1 wherein η.sup.3-allyl is an allyl ligand selected from: (a) η.sup.3—C.sub.nH.sub.(2n-1); (b) η.sup.3—CH.sub.2CH(CH.sub.3).sub.2; (c) η.sup.3—CH.sub.2CHCHSi(CH.sub.3).sub.3; (d) η.sup.3—CH.sub.2CHCH(C.sub.6H.sub.5); and (e) η.sup.3—CH(C.sub.6H.sub.5)CHCH(C.sub.6H.sub.5); wherein n is an integer from 3 to 10.

3. The process of claim 1 wherein the conditions include a temperature ranging from 25° C. to 200° C.; a pressure ranging from 101 kilopascals to 10,500 kilopascals; and a time ranging from 0.5 hour to 100 hours.

4. The process of claim 3 wherein the pressure ranges from 101 kilopascals to 5,000 kilopascals; and wherein when M is tungsten, the temperature ranges from 60° C. to 200° C., and wherein when M is molybdenum, the temperature ranges from 25° C. to 150° C.

5. The process of claim 1 wherein the alkyl-containing compound has a carbon number ranging from 2 to 20 carbons.

6. The process of claim 1 wherein the alkyl-containing compound contains no more than 0.01 weight percent of water prior to the reaction.

7. The process of claim 1 wherein the olefin includes at least a portion of one or more terminal olefins.

8. The process of claim 1 wherein the transition metal complex is selected from the group consisting of (a) (η.sup.5—C.sub.5(CH.sub.3).sub.5)W(NO)(CH.sub.2C(CH.sub.3).sub.3).sub.2; (b) (η.sup.5—C.sub.5(CH.sub.3).sub.5)Mo(NO)(CH.sub.2C(CH.sub.3).sub.3).sub.2; (c) (η.sup.5—C.sub.5H.sub.5)W(NO)(CH.sub.2C(CH.sub.3).sub.3).sub.2; (d) (η.sup.5—C.sub.5(CH.sub.3).sub.4(C.sub.2H.sub.5))W(NO)(CH.sub.2C(CH.sub.3).sub.3).sub.2; (e) (η.sup.5—C.sub.5(CH.sub.3).sub.5)W(NO)(CH.sub.2C(CH.sub.3).sub.3)(CH.sub.2Si(CH.sub.3).sub.3); (f) (η.sup.5—C.sub.5(CH.sub.3).sub.5)W(NO)(H)(η.sup.3—CH.sub.2CHCH(C.sub.6H.sub.5)); (g) (η.sup.5—C.sub.5(CH.sub.3).sub.5)W(NO)(H)(η.sup.3—CH.sub.2CHC(CH.sub.3).sub.2); (h) (η.sup.5—C.sub.5(CH.sub.3).sub.5)W(NO)(H)(η.sup.3—C.sub.5H.sub.9); (i) (η.sup.5 C.sub.5H.sub.4CH(CH.sub.3).sub.2)W(CH.sub.2C(CH.sub.3).sub.3).sub.2; and (j) combinations thereof.

Description

EXAMPLE 1

I. Preparation of (η.SUP.5.—C.SUB.5.(CH.SUB.3.).SUB.5.)W(NO)(CH.SUB.2.C(CH.SUB.3.).SUB.3.).SUB.2 .(Transition Metal Complex (TMC) 1)

[0022] In a glove box, a Schlenk flask is charged with (η.sup.5—C.sub.5(CH.sub.3).sub.5)W(NO)Cl.sub.2 (8.537 grams (g), 20.33 millimoles (mmol) and tetrahydrofuran (THF) (approximately (ca.) 150 milliliters (mL)), then cooled to −78° C. in a dry ice/acetone bath. A second Schlenk flask is charged in the glove box with the reagent Mg(CH.sub.2C(CH.sub.3).sub.3).sub.2 (Titre: 122 grams per mole (g/mol), 2.473 g, 20.27 mmol) and THF (ca. 50 mL), and this mixture is added slowly via cannula to the original Schlenk flask. After the addition is complete, the Schlenk flask is removed from the cold bath, and its contents are stirred at room temperature for 0.5 h to obtain a dark purple mixture. The THF is removed in vacuo, and the contents are transferred with diethyl ether (Et.sub.2O) (6 mL×25 mL) to a second flask at −78° C. which is charged with Mg(CH.sub.2C(CH.sub.3).sub.3).sub.2 (Titre: 122 g/mol, 2.531 g, 20.75 mmol), Et.sub.2O (ca. 25 mL), and a magnetic stir bar. The flask is then removed from the dry ice/acetone bath, and its contents are stirred at room temperature for 2.5 h to obtain a burgundy-colored mixture that is transferred directly to the top of a basic alumina column (3 centimeters (cm)×6 cm) made up in diethyl ether (Et.sub.2O). Elution of the column with Et.sub.2O develops a pink-red band that elutes as a red solution. Removing the solvent from the eluate in vacuo affords (η.sup.5—C.sub.5(CH.sub.3).sub.5)W(NO)(CH.sub.2C(CH.sub.3).sub.3).sub.2 (TMC 1) as a burgundy-colored solid (6.767 g, 68 percent (%) yield). See also, e.g., Bau, R.; Mason, S. A.; Patrick, B. O.; Adams, C. S.; Sharp, W. B.; Legzdins, P. “Alpha-Agostic Interactions in Cp*W(NO)(CH.sub.2CMe.sub.3).sub.2 and Related Nitrosyl Complexes,” Organometallics 2001, 20, 4492-4501, which includes characterization data of a material corresponding to TMC 1.

II. Dehydrodegenations Using (η.SUP.5.—C.SUB.5.(CH.SUB.3.).SUB.5.)W(NO)(CH.SUB.2.C(CH.SUB.3.).SUB.3.).SUB.2 .(TMC 1)

[0023] (A) Dehydrogenation of Dried n-Pentane.

[0024] In a glove box a glass Schlenk flask is charged with (η.sup.5—C.sub.5(CH.sub.3).sub.5)W(NO)(CH.sub.2C(CH.sub.3).sub.3).sub.2 (TMC 1) (0.105 g, 0.214 mmol) and n-pentane (ca. 15 mL). The Schlenk flask is sealed with a KONTES™ (KONTES™ is a trademark of Kimble Kontes Asset Mgmt. Inc.) greaseless stopcock, and then its contents are heated for 15 h at 81° C. to produce a brown mixture. Analysis of the crude reaction mixture by .sup.1H NMR spectroscopy reveals the presence of 1-pentene and 2-pentene as well as three isomers of (η.sup.5—C.sub.5(CH.sub.3).sub.5)W(NO)(H)(η.sup.3—C.sub.5H.sub.9) (TMC 8). The ratio of terminal to internal pentene is 76:24. The volatile components of the reaction mixture are removed in vacuo to obtain (η.sup.5—C.sub.5(CH.sub.3).sub.5)W(NO)(H)(η.sup.3—C.sub.5H.sub.9) (TMC 8) as a brown solid residue (0.083 g, 93% yield). See also, e.g., Baillie, R. A.; Tran, T.; Lalonde, K. M.; Tsang, J. Y. K.; Thibault, M. E.; Patrick, B. O.; Legzdins, P. “Factors Influencing the Outcomes of Inter-molecular CH Activations of Hydrocarbons Initiated by CpW(NO)(CH.sub.2CMe.sub.3)(η.sup.3-Allyl) Complexes (Cp=η.sup.5—C.sub.5Me.sub.5 (Cp*), η.sup.5—C.sub.5Me.sub.4H (Cp′)),” Organometallics 2012, 31, 1055-1067, which includes characterization data for three isomers of a material corresponding to TMC 8.

[0025] (B) Dehydrogenation of Undried n-Pentane.

[0026] Replicate Example 1(II)(A), but replace dried n-pentane with undried n-pentane (water content greater than 0.01 wt %) and carry out dehydrogenation at 81° C. for 61 h. .sup.1H NMR spectroscopic analysis of the crude reaction mixture reveals a selectivity of 1-pentene to 2-pentene of 67:33.

[0027] (C) Dehydrogenation of Undried n-Hexane.

[0028] In a glove box, a glass Schlenk flask is charged with (η.sup.5—C.sub.5(CH.sub.3).sub.5)W(NO)(CH.sub.2C(CH.sub.3).sub.3).sub.2 (TMC 1) (0.172 g, 0.350 mmol) and undried n-hexane (ca. 15 mL). The Schlenk flask is then sealed with a KONTES™ greaseless stopcock, and then its contents are heated for 16 h at 81° C. to produce a dark brown mixture. Analysis of the crude reaction mixture by .sup.1H NMR spectroscopy reveals the presence of isomers of hexene and isomers of (η.sup.5—C.sub.5(CH.sub.3).sub.5)W(NO)(H)(η.sup.3—C.sub.6H.sub.11) (TMC 9). The ratio of 1-hexene to the internal isomers of hexene is 65:35. The volatile components of the reaction mixture are removed in vacuo and TMC 9 is obtained as a brown solid residue (0.148 g, 98% yield). TMC 9 is characterized by .sup.1H NMR spectroscopy, IR spectroscopy, and mass spectrometry.

[0029] (D) Dehydrogenation of Undried n-Octane.

[0030] Replicate Example 1(II)(A), but replace dried n-pentane with undried n-octane (ca. 15 mL), use (η.sup.5—C.sub.5(CH.sub.3).sub.5)W(NO)(CH.sub.2C(CH.sub.3).sub.3).sub.2 (TMC 1) (0.094 g, 0.248 mmol), and heat the contents of the flask for 90 h at 90° C. A dark brown final mixture is obtained, and an analysis of the mixture by .sup.1H NMR spectroscopy reveals the ratio of 1-octene to all internal isomers of octene is 35:65.

[0031] (E) Dehydrogenation of Undried Ethylbenzene.

[0032] In a glove box, a sample of (η.sup.5—C.sub.5(CH.sub.3).sub.5)W(NO)(CH.sub.2C(CH.sub.3).sub.3).sub.2 (TMC 1) (0.093 g, 0.19 mmol) is dissolved in undried ethylbenzene (ca. 5 mL) and transferred to a Schlenk flask, which is then sealed with a greaseless KONTES™ stopcock. The flask is placed in an 81° C. ethylene glycol bath for 16 h to produce a dark purple mixture. Analysis of the crude reaction mixture by .sup.1H NMR spectroscopy reveals the presence of styrene.

[0033] (F) Dehydrogenation of Undried Propylbenzene.

[0034] Replicate Example 1(II)(E), using (η.sup.5—C.sub.5(CH.sub.3).sub.5)W(NO)(CH.sub.2C(CH.sub.3).sub.3).sub.2 (TMC 1) (0.142 g, 0.289 mmol) and undried propylbenzene (ca. 5 mL) in place of ethylbenzene. The mixture is heated using an ethylene glycol bath at 81° C. for 16 h whereupon the solution changes from burgundy to dark purple in color. An analysis of the crude reaction mixture is performed by .sup.1H NMR spectroscopy to reveal the presence of trans-6-methylstyrene.

EXAMPLE 2

I. Preparation of (η.SUB.5.—C.SUB.5.(CH.SUB.3.).SUB.5.)Mo(NO)(CH.SUB.2.C(CH.SUB.3.).SUB.3.).SUB.2 .(TMC 2)

[0035] Replicate Example 1(1), preparation of TMC 1, but use (η.sup.5—C.sub.5(CH.sub.3).sub.5)Mo(NO)Cl.sub.2 (3.848 g, 11.58 mmol) and Mg(CH.sub.2C(CH.sub.3).sub.3).sub.2 (Titre: 142 g/mol, 1.643 g, 11.57 mmol), to form (η.sup.5—C.sub.5(CH.sub.3).sub.5)Mo(NO)—(CH.sub.2C(CH.sub.3).sub.3)Cl as a dark purple solid. The second Schlenk flask is charged with Mg(CH.sub.2C(CH.sub.3).sub.3).sub.2 (Titre: 142 g/mol, 1.668 g, 11.75 mmol) to obtain (η.sup.5—C.sub.5(CH.sub.3).sub.5)Mo(NO)(CH.sub.2C(CH.sub.3).sub.3).sub.2 (TMC 2) as a burgundy solid (2.993 g, 63% yield). See also, e.g., Pamplin, C. B.; Legzdins, P., ibid., which includes characterization data of a material corresponding to TMC 2.

II. Dehydrogenations Using (η.SUP.5.—C.SUB.5.(CH.SUB.3.).SUB.5.)Mo(NO)(CH.SUB.2.C(CH.SUB.3.).SUB.3.).SUB.2 .(TMC 2)

[0036] (A) Dehydrogenation of Undried n-Pentane.

[0037] In a glove box a glass Schlenk flask is charged with (η.sup.5—C.sub.5(CH.sub.3).sub.5)Mo(NO)(CH.sub.2C(CH.sub.3).sub.3).sub.2 (TMC 2) (0.160 g, 0.397 mmol) and undried n-pentane (ca. 15 mL) and then sealed with a KONTES™ greaseless stopcock. The Schlenk flask is placed in an ethylene glycol bath maintained at 40° C. for 4 days (d) to obtain a dark brown mixture. Volatiles are removed by distillation from the final mixture and analyzed by .sup.1H NMR spectroscopy which reveals the formation of 1-pentene exclusively.

[0038] (B) Dehydrogenation of Undried n-Hexane.

[0039] Replicate Example 2(II)(A), using (η.sup.5—C.sub.5(CH.sub.3).sub.5)Mo(NO)(CH.sub.2C(CH.sub.3).sub.3).sub.2 (TMC 2) (0.081 g, 0.20 mmol) and undried n-hexane (ca. 15 mL), stir the mixture at room temperature for 16 h to obtain a dark brown mixture. Analysis of the reaction mixture by .sup.1H NMR spectroscopy reveals the formation of 1-hexene exclusively.

[0040] (C) Dehydrogenation of Undried n-Octane.

[0041] Replicate Example 2(II)(A), using (η.sup.5—C.sub.5(CH.sub.3).sub.5)Mo(NO)(CH.sub.2C(CH.sub.3).sub.3).sub.2 (TMC 2) (0.133 g, 0.327 mmol) and undried n-octane (ca. 18 mL), and the flask is then sealed with a KONTES™ greaseless stopcock. The burgundy-colored mixture is stirred at room temperature for 2.5 d to obtain a dark brown mixture. Analysis of this mixture by .sup.1H NMR spectroscopy reveals the exclusive formation of 1-octene.

EXAMPLE 3

I. Preparation of (η.SUP.5.—C.SUB.5.H.SUB.5.)W(NO)(CH.SUB.2.C(CH.SUB.3.).SUB.3.).SUB.2 .(TMC 3)

[0042] Replicate Example 1(1), preparation of TMC 1, but use (η.sup.5—C.sub.5H.sub.5)W(NO)Cl.sub.2 (2.721 g, 7.78 mmol), Mg(CH.sub.2C(CH.sub.3).sub.3).sub.2 (Titre: 115 g/mol, 0.855 g, 7.44 mmol), to form (η.sup.5—C.sub.5H.sub.5)W(NO)(CH.sub.2C(CH.sub.3).sub.3)Cl as a purple solid. The second Schlenk flask is charged with Mg(CH.sub.2C(CH.sub.3).sub.3).sub.2 (Titre: 115 g/mol, 0.850 g, 7.39 mmol) to obtain (η.sup.5—C.sub.5H.sub.5)W(NO)(CH.sub.2C(CH.sub.3).sub.3).sub.2 (TMC 3) as a dark red solid (0.850 g, 27% yield). See also, e.g., Legzdins, P.; Rettig, S. J.; Sanchez, L. “Organometallic nitrosyl chemistry. 37. Synthesis, characterization, and some chemical properties of unusual 16-electron dialkyl (η.sup.5-cyclopentadienyl)-nitrosylmolybdenum and tungsten complexes,” Organometallics 1988, 7, 2394-2403, which includes characterization data of a material corresponding to TMC 3.

II. Dehydrogenation Using (η.SUP.5.—C.SUB.5.H.SUB.5.)W(NO)(CH.SUB.2.C(CH.SUB.3.).SUB.3.).SUB.2 .(TMC 3)

[0043] (A) Dehydrogenation of Undried n-Pentane.

[0044] Replicate Example 1(II)(A), using (η.sup.5—C.sub.5H.sub.5)W(NO)(CH.sub.2C(CH.sub.3).sub.3).sub.2 (TMC 3) (0.260 g, 0.617 mmol) and undried n-pentane (ca. 10 mL), and the flask is then sealed with a KONTES™ greaseless stopcock. The Schlenk flask is placed in an ethylene glycol bath maintained at 81° C. for 70 h to obtain a dark brown mixture. .sup.1H NMR spectroscopic analysis of the crude reaction mixture reveals a selectivity of 1-pentene to 2-pentene of 67:33.

EXAMPLE 4

I. Preparation of (η.SUP.5.—C.SUB.5.(CH.SUB.3.).SUB.4.(C.SUB.2.H.SUB.5.))W(NO)(CH.SUB.2.C(CH.SUB.3.).SUB.3.).SUB.2 .(TMC 4)

[0045] In a glove box, a Schlenk flask is charged with (η.sup.5—C.sub.5(CH.sub.3).sub.4(C.sub.2H.sub.5))W(NO)Cl.sub.2 (2.918 g, 6.74 mmol), a light green powder, Mg(CH.sub.2C(CH.sub.3).sub.3).sub.2 (Titre: 118 g/mol, 0.794 g, 6.73 mmol), a white powder, and a magnetic stir bar. The mixture is cooled to −196° C. with a liquid nitrogen bath and Et.sub.2O (ca. 150 mL) is added dropwise via cannulation. The Schlenk flask is warmed to room temperature while being stirred for 1 h, resulting in a dark purple solution. A second Schlenk flask is charged with Mg(CH.sub.2C(CH.sub.3).sub.3).sub.2 (Titre: 118 g/mol, 0.822 g, 6.966 mmol), which is cooled to −196° C. using a liquid nitrogen bath. The mixture from the first flask is then transferred dropwise via cannulation into the second flask. After the addition the flask is allowed to warm up to room temperature while being stirred for 1 h to produce a dark maroon-colored solution. The mixture is then filtered through CELITE™ (CELITE™ is a trademark of Imerys Minerals California, Inc.) using a porous frit to remove the magnesium salts. The solvent is removed in vacuo to give an oily residue. The sample is re-dissolved in pentane and chromatographed on a basic alumina column (3.5 cm×0.5 cm). A maroon-colored band is eluted with 3:1 pentane/Et.sub.2O to give a maroon solution. Solvent is removed in vacuo and affords (η.sup.5—C.sub.5(CH.sub.3).sub.4(C.sub.4H.sub.5))W(NO)(CH.sub.2C(CH.sub.3).sub.3).sub.2 (TMC 4) as maroon-colored needles (1.042 g, 31% yield). Characterization data confirming TMC 4 is obtained via .sup.1H and .sup.13C NMR spectroscopy, IR spectroscopy and mass spectrometry.

II. Dehydrogenation Using (η.SUP.5.—C.SUB.5.(CH.SUB.3.).SUB.4.(C.SUB.2.H.SUB.5.))W(NO)(CH.SUB.2.C(CH.SUB.3.).SUB.3.).SUB.2 .(TMC 4)

[0046] (A) Dehydrogenation of Undried n-Pentane.

[0047] Replicate Example 1(II)(A), using (η.sup.5—C.sub.5(CH.sub.3).sub.4(C.sub.2H.sub.5))W(NO)(CH.sub.2C(CH.sub.3).sub.3).sub.2 (TMC 4) (0.100 g, 0.198 mmol) and undried n-pentane (ca. 10 mL), and the flask is then sealed with a KONTES™ greaseless stopcock. The Schlenk flask is placed in an ethylene glycol bath maintained at 81° C. for 61 h to obtain a dark brown mixture. .sup.1H NMR spectroscopic analysis of the crude reaction mixture reveals a selectivity of 1-pentene to 2-pentene of 76:24.

EXAMPLE 5

I. Preparation of (η.SUP.5.—C.SUB.5.(CH.SUB.3.).SUB.5.)W(NO)(CH.SUB.2.C(CH.SUB.3.).SUB.3.)(CH.SUB.2.Si(CH.SUB.3.).SUB.3.)(TMC 5)

[0048] Replicate Example 1(1), preparation of TMC 1, but use (η.sup.5—C.sub.5(CH.sub.3).sub.5)W(NO)Cl.sub.2 (3.289 g, 7.829 mmol), Mg(CH.sub.2C(CH.sub.3).sub.3).sub.2 (Titre: 130 g/mol, 1.013 g, 7.79 mmol), to form (η.sup.5—C.sub.5(CH.sub.3).sub.5)W(NO)—(CH.sub.2C(CH.sub.3).sub.3)Cl as a dark purple solid. The second Schlenk flask is charged with Mg(CH.sub.2Si(CH.sub.3).sub.3).sub.2 (Titre: 200 g/mol, 1.582 g, 7.91 mmol) to obtain (η.sup.5—C.sub.5(CH.sub.3).sub.5)W(NO)(CH.sub.2C(CH.sub.3).sub.3)(CH.sub.2Si(CH.sub.3).sub.3) (TMC 5) as a purple solid (2.148 g, 54% yield). Characterization data confirming TMC 5 is obtained via .sup.1H and .sup.13C NMR spectroscopy, IR spectroscopy and mass spectrometry.

II. Dehydrogenation Using (η.SUP.5.—C.SUB.5.(CH.SUB.3.).SUB.5.)W(NO)(CH.SUB.2.C(CH.SUB.3.).SUB.3.)(CH.SUB.2.Si(CH.SUB.3.).SUB.3.) (TMC 5)

[0049] (A) Dehydrogenation of Undried n-Pentane.

[0050] Replicate Example 1(II)(A), using (η.sup.5—C.sub.5(CH.sub.3).sub.5)W(NO)(CH.sub.2C(CH.sub.3).sub.3)(CH.sub.2Si(CH.sub.3).sub.3) (TMC 5) (0.057 g, 0.112 mmol) and undried n-pentane (ca. 10 mL), and the flask is then sealed with a KONTES™ greaseless stopcock. The Schlenk flask is placed in an ethylene glycol bath maintained at 120° C. for 20 h to obtain a dark brown mixture. .sup.1H NMR spectroscopic analysis of the crude reaction mixture reveals a selectivity of 1-pentene to 2-pentene of 70:30.

EXAMPLE 6

I. Preparation of (η.SUP.5.—C.SUB.5.(CH.SUB.3.).SUB.5.)W(NO)(H)(η.SUP.3.—CH.SUB.2.CHCH(C.SUB.6.H.SUB.5.)) (TMC 6)

[0051] In a glove box, a Schlenk flask is charged with (η.sup.5—C.sub.5(CH.sub.3).sub.5)W(NO)Cl.sub.2 (5.000 g, 11.90 mmol) and a magnetic stir bar. A second Schlenk flask is charged with Mg(CH.sub.2CH═CH(C.sub.6H.sub.5)).sub.2 (Titre: 218 g/mol, 2.592 g, 11.90 mmol) and a magnetic stir bar. On a Schlenk line under argon, dry THF (ca. 100 mL each) is cannulated into each Schlenk flask, and each mixture is stirred until all solid material dissolved. Both Schlenk flasks are then placed into a dry ice/acetone bath (−78° C.) while stirring of their contents is maintained. Once cold, the contents of the second Schlenk flask are cannulated slowly into the first Schlenk flask. The resulting mixture is then removed from the cold bath and is allowed to reach room temperature while being stirred for 1 h. The first Schlenk flask is then placed back into the dry ice/acetone bath, and its contents are cooled to −78° C. A solution of lithium borohydride (LiBH.sub.4) in THF (2.0 M, 6.5 mL, 13 mmol) is added to the Schlenk flask in a dropwise fashion. The mixture develops a strong red-brown color, and it is removed from the cold bath and allowed to reach room temperature while being stirred for 3 h. Removal of the THF in vacuo leaves behind a reddish brown oily residue. On the bench top, this residue is re-dissolved in Et.sub.2O and the mixture is then filtered through CELITE™ using a porous frit to remove the magnesium salts. The ether layer is dark reddish brown in color at this stage, and it is reduced in volume in vacuo to obtain a concentrated solution of the crude product. Purification is performed over neutral alumina, with the chromatography column (10 cm×2.5 cm) being prepared with hexanes. A yellow band is eluted with a gradient of 0-50% Et.sub.2O in hexane to give a yellow solution. Solvent is removed in vacuo and affords (η.sup.5—C.sub.5(CH.sub.3).sub.5)W(NO)(H)(η.sup.3—CH.sub.2CHCH(C.sub.6H.sub.5)) (TMC 6) as a yellow powder (1.1145 g, 20% yield). Characterization data for TMC 6 is obtained, including .sup.1H and .sup.13C NMR spectroscopy, IR spectroscopy and mass spectrometry.

II. Dehydrogenation Using (η.SUP.5.—C.SUB.5.(CH.SUB.3.).SUB.5.)W(NO)(H)(η.SUP.3.—CH.SUB.2.CHCH(C.SUB.6.H.SUB.5.)) (TMC 6)

[0052] (A) Dehydrogenation of Undried n-Pentane.

[0053] Replicate Example 1(II)(A), using (η.sup.5—C.sub.5(CH.sub.3).sub.5)W(NO)(H)(η.sup.3—CH.sub.2CHCH(C.sub.6H.sub.5)) (TMC 6) (0.0844 g, 0.180 mmol) and undried n-pentane (ca. 15 mL), and the flask is then sealed with a KONTES™ greaseless stopcock. The Schlenk flask is placed in an ethylene glycol bath maintained at 81° C. for 5 d, subsequently placed in an ethylene glycol bath maintained at 120° C. for 12 h to obtain a dark brown mixture. .sup.1H NMR spectroscopic analysis of the crude reaction mixture reveals a selectivity of 1-pentene to 2-pentene of 61:39.

EXAMPLE 7

I. Preparation of (η.SUP.5.—C.SUB.5.(CH.SUB.3.).SUB.5.)W(NO)(H)(η.SUP.3.—CH.SUB.2.CHC(CH.SUB.3.).SUB.2.) (TMC 7)

[0054] In a glove box, a glass Schlenk flask is charged with (η.sup.5—C.sub.5(CH.sub.3).sub.5)W(NO)Cl.sub.2 (4.210 g, 10.00 mmol) and THF (ca. 60 mL), and then cooled in a dry ice/acetone bath (−78° C.). A second Schlenk flask is charged with Mg(CH.sub.2CHC(CH.sub.3).sub.2).sub.2 (Titre: 128 g/mL, 1.314 g, 10.00 mmol) and THF (ca. 50 mL), and then its contents are transferred to the first flask dropwise via cannula. Following this addition, the reaction mixture is allowed to warm to room temperature and is then stirred for 1 h to obtain a yellow-brown mixture. The Schlenk flask is again cooled again to −78° C., and LiBH.sub.4 in THF (2.0 M, 5.0 mL, 10.00 mmol) is added slowly via syringe. The contents of the Schlenk flask are warmed to room temperature and stirred for 3 h to obtain a brown mixture. The THF is removed from this mixture in vacuo, and the residue is taken up in Et.sub.2O (ca. 50 mL) and washed with H.sub.2O (3×50 mL). The Et.sub.2O layer is filtered through a glass frit, and then the solvent is removed from the filtrate under reduced pressure to obtain a brown solid. The solid is re-dissolved in Et.sub.2O, and the solution is transferred to the top of a basic alumina column (3 cm×5 cm) that has been made up in hexanes. A yellow band is developed with Et.sub.2O as eluent and is collected as a yellow eluate. The Et.sub.2O is removed from the eluate in vacuo, and the residue is washed with cold pentane to obtain (η.sup.5—C.sub.5(CH.sub.3).sub.5)W(NO)(H)(η.sup.3—CH.sub.2CHC(CH.sub.3).sub.2) (TMC 7) as a yellow solid (2.866 g, 65% yield).

II. Dehydrogenation Using (η.SUP.5.—C.SUB.5.(CH.SUB.3.).SUB.5.)W(NO)(H)(η.SUP.3.—CH.SUB.2.CHC(CH.SUB.3.).SUB.2.) (TMC 7)

[0055] (A) Dehydrogenation of Dried n-Pentane

[0056] Replicate Example 1(II)(A), using (η.sup.5—C.sub.5(CH.sub.3).sub.5)W(NO)(H)(η.sup.3—CH.sub.2CHC(CH.sub.3).sub.2) (TMC 7) (0.079 g, 0.188 mmol) and dried n-pentane (ca. 10 mL), and the flask is then sealed with a KONTES™ greaseless stopcock. The Schlenk flask is placed in an ethylene glycol bath maintained at 81° C. for 3 d to obtain a dark brown mixture. .sup.1H NMR spectroscopic analysis of the crude reaction mixture reveals a selectivity of 1-pentene to 2-pentene of 70:30.

EXAMPLE 8

I. Preparation of (η.SUP.5.—C.SUB.5.(CH.SUB.3.).SUB.5.)W(NO)(H)(η.SUP.3.—C.SUB.5.H.SUB.9.) (TMC 8)

[0057] In a glove box, a Schlenk flask is charged with (η.sup.5—C.sub.5(CH.sub.3).sub.5)W(NO)(CH.sub.2C(CH.sub.3).sub.3).sub.2 (TMC 1) (1.065 g, 2.17 mmol) and dried n-pentane (ca. 300 mL) and then sealed with a KONTES™ stopcock. The Schlenk flask is placed in an ethylene glycol bath maintained at 81° C. for 16 h. The solution changes from burgundy to brown in color. Once removed from the bath, all of the solvent and volatiles are removed from the mixture in vacuo. The solid is re-dissolved in Et.sub.2O, and the solution is transferred to the top of a basic alumina column (3 cm×10 cm) made up in hexanes. A yellow band is developed with Et.sub.2O as eluent and is collected as a yellow eluate. The Et.sub.2O is removed from the eluate in vacuo, and the residue is washed with cold pentane to obtain (η.sup.5—C.sub.5(CH.sub.3).sub.5)W(NO)(H)(η.sup.3—C.sub.5H.sub.9) (TMC 8) as a yellow solid (0.331 g, 36% yield). See also, e.g., Baillie, R. A.; Tran, T., et al., ibid., which includes characterization data corresponding to a TMC 8 material.

II. Dehydrogenation with (η.SUP.5.—C.SUB.5.(CH.SUB.3.).SUB.5.)W(NO)(H)(η.SUP.3.—C.SUB.5.H.SUB.9.) (TMC 8)

[0058] (A) Dehydrogenation of Undried Propylbenzene.

[0059] In a glove box a Schlenk flask is charged with (η.sup.5—C.sub.5(CH.sub.3).sub.5)W(NO)(H)(η.sup.3—C.sub.5H.sub.9) (TMC 8) and undried propylbenzene (ca. 10 mL) and then sealed with a KONTES™ greaseless stopcock. The Schlenk flask is placed in an ethylene glycol bath maintained at 71° C. for 90 h. An analysis of a sample from the final reaction mixture is performed by .sup.1H NMR spectroscopy which confirms the formation of trans-6-methylstyrene.

EXAMPLE 9

I. Preparation of (η.SUP.5.—C.SUB.5.H.SUB.4.CH(CH.SUB.3.).SUB.2.)W(CH.SUB.2.C(CH.SUB.3.).SUB.3.).SUB.2 .(TMC 10)

[0060] A standard solution of (η.sup.5—C.sub.5H.sub.4CH(CH.sub.3).sub.2)W(NO)(CO).sub.2 in Et.sub.2O (9.5 mL) is prepared under anaerobic conditions. An aliquot (0.3 mL) is extracted via syringe and combined with a known amount of ferrocene (0.0216 g, 0.116 mmol) to determine the concentration of the (η.sup.5—C.sub.5H.sub.4CH(CH.sub.3).sub.2)W(NO)(CO).sub.2 (11.4 mmol) via integration of the .sup.1H NMR spectrum of the sample in benzene-d.sub.6. In the glovebox, a Schlenk flask is charged with PCl.sub.5 (2.350 g, 11.3 mmol). The contents of the Schlenk are cooled to −196° C. with a liquid nitrogen bath and Et.sub.2O (ca. 150 mL) is added via cannulation, followed by addition of the orange standard solution. The Schlenk flask is warmed to room temperature while being stirred for 2 h, resulting in a dark green solution of (η.sup.5—C.sub.5H.sub.4CH(CH.sub.3).sub.2)W(NO)Cl.sub.2. In the glovebox, a second Schlenk flask is charged with Mg(CH.sub.2C(CH.sub.3).sub.3).sub.2 (Titre: 170.5 g/mol, 1.955 g, 11.5 mmol) and Et.sub.2O (ca. 100 mL). The mixture is then transferred dropwise via cannulation into the reaction Schlenk flask with (η5-C.sub.5H.sub.4CH(CH.sub.3).sub.2)W(NO)Cl.sub.2 placed into a dry ice/acetone bath (−78° C.). The flask is then removed from the bath, and its contents are stirred at room temperature for 30 minutes (min) to produce a dark brown solution. The mixture is then filtered through CELITE™ using a porous frit to remove the magnesium salts. The sample is transferred into another reaction Schlenk flask charged with Mg(CH.sub.2C(CH.sub.3).sub.3).sub.2 (Titre: 170.5 g/mol, 1.950 g, 11.4 mmol) and Et.sub.2O (ca. 100 mL) at −78° C. The flask is then removed from the dry ice/acetone bath, and its contents are stirred at room temperature for 30 min to obtain burgundy-colored mixture. After the volume of the reaction mixture is reduced in vacuo, the solution is transferred to the top of a basic alumina column (3 cm×6 cm) made up in Et.sub.2O. A red band is eluted with Et.sub.2O to give a burgundy solution. Solvent is removed in vacuo to afford (η.sup.5—C.sub.5H.sub.4CH(CH.sub.3).sub.2)W(CH.sub.2C(CH.sub.3).sub.3).sub.2 as a burgundy-colored solid (1.787 g, 3.86 mmol, 34% yield).

[0061] Characterization data included .sup.1H NMR spectroscopy, IR spectroscopy, and mass spectrometry.

II. Dehydrogenation Using (η.SUP.5.—C.SUB.5.H.SUB.4.CH(CH.SUB.2.)W(CH.SUB.2.CMe.SUB.3.).SUB.2 .(TMC 10)

[0062] (A) Dehydrogenation of Undried n-Pentane.

[0063] Replicate Example 1(II)(A), using (η.sup.5—C.sub.5H.sub.4CH(CH.sub.3).sub.2)W(CH.sub.2C(CH.sub.3).sub.3).sub.2 (0.106 g, 0.229 mmol) and undried n-pentane (ca. 10 mL). The Schlenk flask is placed in an ethylene glycol bath maintained at 60° C. for 2 d to obtain a dark brown mixture. .sup.1H NMR spectroscopic analysis of the crude reaction mixture reveals a selectivity of 1-pentene to 2-pentene of 70:30.

[0064] Table 1 includes TMCs 1-10 and shows the dehydrogenation performance data for each, except for TMC 9, which has not been tested in a dehydrogenation.

TABLE-US-00001 TABLE 1 Identification of TMCs 1-10 and Dehydrogenation Performance Data for TMCs 1-8 and 10 TMC # TMC formula Dehydrogenation Substrate Dehydrogenation Yield and Ratio 1 (η.sup.5-C.sub.5(CH.sub.3).sub.5)W(NO)(CH.sub.2C(CH.sub.3).sub.3).sub.2 n-pentane (dried*) 1-pentene:2-pentene 76:24 n-pentane (undried**) 1-pentene:2-pentene 67:33 n-hexane (undried) 1-hexene:internal isomers 65:35 n-octane (undried) 1-octene:internal isomers 35:65 ethylbenzene (undried) styrene propylbenzene (undried) trans-β-methylstyrene 2 (η.sup.5-C.sub.5(CH.sub.3).sub.5)Mo(NO)(CH.sub.2C(CH.sub.3).sub.3).sub.2 n-pentane (undried) 1-pentene n-hexane (undried) 1-hexene n-octane (undried) 1-octene 3 (η.sup.5-C.sub.5H.sub.5)W(NO)(CH.sub.2C(CH.sub.3).sub.3).sub.2 n-pentane(undried) 1-pentene:2-pentene 67:33 4 (η.sup.5-C.sub.5(CH.sub.3).sub.4(C.sub.2H.sub.5))W(NO)(CH.sub.2C(CH.sub.3).sub.3).sub.2 n-pentane (undried) 1-pentene:2-pentene 72:28 5 (η.sup.5-C.sub.5(CH.sub.3).sub.5)W(NO)(CH.sub.2C(CH.sub.3).sub.3)(CH.sub.2Si(CH.sub.3).sub.3) n-pentane (undried) 1-pentene:2-pentene 70:30 6 (η.sup.5-C.sub.5(CH.sub.3).sub.5)W(NO)(H)(η.sup.3-CH.sub.2CHCH(C.sub.6H.sub.5)) n-pentane (undried) 1-pentene:2-pentene 61:39 7 (η.sup.5-C.sub.5(CH.sub.3).sub.5)W(NO)(H)(η.sup.3-CH.sub.2CHC(CH.sub.3).sub.2) n-pentane (dried) 1-pentene:2-pentene 70:30 8 (η.sup.5-C.sub.5(CH.sub.3).sub.5)W(NO)(H)(η.sup.3-C.sub.5H.sub.9) propylbenzene (undried) trans-β-methylstyrene 9 (η.sup.5-C.sub.5(CH.sub.3).sub.5)W(NO)(H)(η.sup.3-C.sub.6H.sub.11) n/a n/a 10 (η.sup.5-C.sub.5H.sub.4CH(CH.sub.3).sub.2)W(CH.sub.2C(CH.sub.3).sub.3).sub.2 n-pentane (undried) 1-pentene:2-pentene 70:30 *dried indicates that the alkyl containing compound contains less than 0.0001 wt % of water prior to reaction. **undried indicates that the alkyl containing compound contains from 0.0001 to 0.01 wt % of water prior to reaction. n/a indicates not tested in a dehydrogenation