CATALYSTS SUITABLE FOR THE RING-OPENING POLYMERISATION OF CYCLIC ESTERS AND CYCLIC AMIDES
20210130542 · 2021-05-06
Inventors
Cpc classification
B01J2540/40
PERFORMING OPERATIONS; TRANSPORTING
B01J2540/10
PERFORMING OPERATIONS; TRANSPORTING
B01J31/2243
PERFORMING OPERATIONS; TRANSPORTING
B01J31/223
PERFORMING OPERATIONS; TRANSPORTING
B01J2540/225
PERFORMING OPERATIONS; TRANSPORTING
C08G63/823
CHEMISTRY; METALLURGY
International classification
Abstract
A new family of Group IV transition metal catalytic compounds are provided, which are capable of catalysing the ROP of cyclic esters and cyclic amides to yield polymers of high molecular weight and narrow PDI. The new family of catalysts are surprisingly active not only in catalysing the ROP of lactones such as caprolactone, but also macrolactones (e.g. ω-pentadecalactone, PDL), where the reduced amount of ring strain would typically compromise efficient polymerisation. Also provided is a process for the ring opening polymerisation (ROP) of a cyclic ester or a cyclic amide employing the new catalytic compounds.
Claims
1. A compound having a structure according to formula (I-A), (I-B) or (I-C) shown below: ##STR00023## wherein M is a Group IV transition metal, each X is independently selected from halo, hydrogen, a phosphonate, sulfonate or boronate group, (1-4C)dialkylamino, (1-6C)alkyl, (1-6C)alkoxy, aryl, and aryloxy, any of which may be optionally substituted one of more groups selected from halo, oxo, hydroxy, amino, nitro, (1-6C)alkyl, (2-6C)alkenyl, (2-6C)alkynyl, (1-6C)haloalkyl, (1-6C)alkoxy, aryl and Si[(1-4C)alkyl].sub.3, R.sub.2 is absent or is selected from hydrogen, halo, oxo, hydroxy, amino, nitro, (1-6C)alkyl, (2-6C)alkenyl, (2-6C)alkynyl, (1-6C)haloalkyl, (1-6C)alkoxy, aryl, aryloxy, heteroaryl, heteroaryloxy, carbocyclyl and heterocyclyl, any of which may be optionally substituted with one or more substituents selected from halo, oxo, hydroxy, amino, nitro, (1-6C)alkyl, (2-6C)alkenyl, (2-6C)alkynyl, (1-6C)haloalkyl and (1-6C)alkoxy, bond a is a carbon-nitrogen single bond (C—N) or a carbon-nitrogen double bond (C═N), with the proviso that when R.sub.2 is absent, bond a is a carbon-nitrogen double bond (C═N), and when R.sub.2 is other than absent, bond a is a carbon-nitrogen single bond (C—N), R.sub.3, R.sub.4, R.sub.5 and R.sub.6 are each independently selected from hydrogen, halo, oxo, hydroxy, amino, nitro, (1-6C)alkyl, (2-6C)alkenyl, (2-6C)alkynyl, (1-6C)haloalkyl, (1-6C)alkoxy, aryl, aryloxy, heteroaryl, heteroaryloxy, carbocyclyl and heterocyclyl, any of which may be optionally substituted with one or more substituents selected from halo, oxo, hydroxy, amino, nitro, (1-6C)alkyl, (2-6C)alkenyl, (2-6C)alkynyl, (1-6C)haloalkyl and (1-6C)alkoxy, R.sub.7 is selected from (1-6C)alkyl, (2-6C)alkenyl, (2-6C)alkynyl, (1-6C)haloalkyl, aryl, heteroaryl, carbocyclyl and heterocyclyl, any of which may be optionally substituted with one or more substituents selected from halo, oxo, hydroxy, amino, nitro, (1-6C)alkyl, (2-6C)alkenyl, (2-6C)alkynyl, (1-6C)haloalkyl and (1-6C)alkoxy, R.sub.1 is a group having the formula (II) shown below: ##STR00024## wherein R.sub.a is selected from (1-6C)alkyl, (2-6C)alkenyl, (2-6C)alkynyl, (1-6C)haloalkyl, (1-6C)alkoxy, aryl, aryloxy, heteroaryl, heteroaryloxy, carbocyclyl and heterocyclyl, any of which may be optionally substituted with one or more substituents selected from halo, oxo, hydroxy, amino, nitro, (1-6C)alkyl, (2-6C)alkenyl, (2-6C)alkynyl, (1-6C)haloalkyl, aryl, aryloxy, heteroaryl, heteroaryloxy, carbocyclyl and heterocyclyl, L is a group —[C(R.sub.x).sub.2].sub.n— wherein each R.sub.x is independently selected from hydrogen, (1-6C)alkyl, (2-6C)alkenyl, (2-6C)alkynyl, (1-6C)haloalkyl, (1-6C)alkoxy, aryl, aryloxy, heteroaryl, heteroaryloxy, carbocyclyl and heterocyclyl, any of which may be optionally substituted with one or more substituents selected from halo, oxo, hydroxy, amino, nitro, (1-6C)alkyl, (2-6C)alkenyl, (2-6C)alkynyl, (1-6C)haloalkyl and aryl, and n is 0, 1, 2, 3 or 4.
2. The compound of claim 1, wherein the compound has a structure according to formula (I-A) or (I-B).
3. The compound of claim 1, wherein the compound has a structure according to formula (I-A).
4. The compound of claim 1, wherein the compound has a structure according to formula (I-B).
5. The compound of claim 1, wherein the compound has a structure according to formula (I-C).
6. The compound of any preceding claim, wherein M is selected from titanium, zirconium and hafnium.
7. The compound of any preceding claim, wherein M is selected from titanium and zirconium.
8. The compound of any preceding claim, wherein M is titanium.
9. The compound of any preceding claim, wherein each X is independently selected from halo, hydrogen, (1-6C)alkoxy, —N(CH.sub.3).sub.2, —N(CH.sub.2CH.sub.3).sub.2 and aryloxy, any of which may be optionally substituted one of more groups selected from halo, oxo, hydroxy, amino, nitro, (1-6C)alkyl, (2-6C)alkenyl, (2-6C)alkynyl, (1-6C)haloalkyl, (1-6C)alkoxy, aryl and Si[(1-4C)alkyl].sub.3.
10. The compound of any preceding claim, wherein each X is independently selected from halo, hydrogen, (1-6C)alkoxy, and aryloxy, any of which may be optionally substituted one of more groups selected from halo, oxo, hydroxy, amino, nitro, (1-6C)alkyl, (2-6C)alkenyl, (2-6C)alkynyl, (1-6C)haloalkyl, (1-6C)alkoxy, aryl and Si[(1-4C)alkyl].sub.3.
11. The compound of any one of claims 1 to 9, wherein each X is independently selected from halo, hydrogen, (1-6C)alkoxy, —N(CH.sub.3).sub.2, —N(CH.sub.2CH.sub.3).sub.2 and aryloxy, any of which may be optionally substituted one of more groups selected from halo, oxo, hydroxy, amino, nitro, (1-6C)alkyl, (1-6C)haloalkyl, (1-6C)alkoxy and aryl.
12. The compound of claim 11, wherein each X is independently selected from halo, hydrogen, (1-6C)alkoxy, and aryloxy, any of which may be optionally substituted one of more groups selected from halo, oxo, hydroxy, amino, nitro, (1-6C)alkyl, (1-6C)haloalkyl, (1-6C)alkoxy and aryl.
13. The compound of any one of claims 1 to 9, wherein each X is independently selected from halo, hydrogen, (1-4C)alkoxy, —N(CH.sub.3).sub.2, —N(CH.sub.2CH.sub.3).sub.2 and phenoxy, any of which may be optionally substituted one of more groups selected from halo, oxo, hydroxy, amino, nitro, (1-4C)alkyl, (1-4C)haloalkyl, (1-4C)alkoxy and phenyl.
14. The compound of claim 13, wherein each X is independently selected from halo, hydrogen, (1-4C)alkoxy, and phenoxy, any of which may be optionally substituted one of more groups selected from halo, oxo, hydroxy, amino, nitro, (1-4C)alkyl, (1-4C)haloalkyl, (1-4C)alkoxy and phenyl.
15. The compound of any preceding claim, wherein each X is independently selected from halo, hydrogen, and (1-4C)alkoxy, any of which may be optionally substituted one of more groups selected from halo, hydroxy, amino, (1-4C)alkyl and (1-4C)alkoxy.
16. The compound of any preceding claim, wherein each X is independently selected from chloro, bromo and (1-4C)alkoxy.
17. The compound of any preceding claim, wherein each X is independently (1-4C)alkoxy.
18. The compound of any preceding claim, wherein each X is isopropoxy.
19. The compound of any one of claims 1 to 9, wherein each X is independently —N(CH.sub.3).sub.2 or —N(CH.sub.2CH.sub.3).sub.2.
20. The compound of any preceding claim, wherein R.sub.2 is absent or hydrogen.
21. The compound of any preceding claim, wherein R.sub.2 is absent.
22. The compound of any one or claims 1 to 20, wherein R.sub.2 is hydrogen.
23. The compound of any preceding claim, wherein R.sub.3, R.sub.4, R.sub.5 and R.sub.6 are each independently selected from hydrogen, halo, oxo, hydroxy, amino, nitro, (1-4C)alkyl, (2-4C)alkenyl, (2-4C)alkynyl, (1-4C)haloalkyl, (1-4C)alkoxy, aryl, aryloxy, heteroaryl, heteroaryloxy, carbocyclyl and heterocyclyl, any of which may be optionally substituted with one or more substituents selected from halo, oxo, hydroxy, amino, nitro, (1-4C)alkyl, (2-4C)alkenyl, (2-4C)alkynyl, (1-4C)haloalkyl and (1-4C)alkoxy.
24. The compound of any preceding claim, wherein R.sub.3, R.sub.4, R.sub.5 and R.sub.6 are each independently selected from hydrogen, halo, oxo, hydroxy, amino, nitro, (1-4C)alkyl, (1-4C)haloalkyl, (1-4C)alkoxy, aryl and heteroaryl, any of which may be optionally substituted with one or more substituents selected from halo, oxo, hydroxy, amino, nitro, (1-4C)alkyl, (1-4C)haloalkyl and (1-4C)alkoxy.
25. The compound of any preceding claim, wherein R.sub.3, R.sub.4, R.sub.5 and R.sub.6 are each independently selected from hydrogen, halo, amino, nitro, (1-4C)alkyl, (1-4C)haloalkyl, (1-4C)alkoxy, aryl and heteroaryl, any of which may be optionally substituted with one or more substituents selected from halo and (1-4C)alkyl.
26. The compound of any preceding claim, wherein R.sub.3 is hydrogen.
27. The compound of any preceding claim, wherein R.sub.3, R.sub.4, R.sub.5 and R.sub.6 are hydrogen.
28. The compound of any preceding claim, wherein R.sub.7 is selected from (1-6C)alkyl, (2-6C)alkenyl, (2-6C)alkynyl, (1-6C)haloalkyl, aryl and heteroaryl, any of which may be optionally substituted with one or more substituents selected from halo, oxo, hydroxy, amino, nitro, (1-6C)alkyl, (1-6C)haloalkyl and (1-6C)alkoxy.
29. The compound of any preceding claim, wherein R.sub.7 is selected from (1-4C)alkyl, (2-4C)alkenyl, (2-4C)alkynyl, (1-4C)haloalkyl, aryl and heteroaryl, any of which may be optionally substituted with one or more substituents selected from halo, oxo, hydroxy, amino, nitro, (1-4C)alkyl, (1-4C)haloalkyl and (1-4C)alkoxy.
30. The compound of any preceding claim, wherein R.sub.7 is selected from (1-4C)alkyl, (1-4C)haloalkyl, aryl and heteroaryl, any of which may be optionally substituted with one or more substituents selected from halo, hydroxy, amino, (1-4C)alkyl and (1-4C)alkoxy.
31. The compound of any preceding claim, wherein R.sub.7 is selected from (1-4C)alkyl and aryl, any of which may be optionally substituted with one or more substituents selected from halo, hydroxy, amino, (1-4C)alkyl and (1-4C)alkoxy.
32. The compound of any preceding claim, wherein R.sub.7 is selected from (1-2C)alkyl and phenyl, any of which may be optionally substituted with one or more substituents selected from halo, hydroxy, amino and (1-4C)alkyl.
33. The compound of any preceding claim, wherein R.sub.7 is selected from (1-2C)alkyl, which may be optionally substituted with one or more substituents selected from halo (e.g. fluoro).
34. The compound of any preceding claim, wherein R.sub.7 is (1-2C)alkyl.
35. The compound of any preceding claim, wherein R.sub.7 is methyl.
36. The compound of any preceding claim, wherein R.sub.a is selected from (1-4C)alkyl, (2-4C)alkenyl, (2-4C)alkynyl, (1-4C)haloalkyl, (1-4C)alkoxy, aryl, aryloxy, heteroaryl, heteroaryloxy, carbocyclyl and heterocyclyl, any of which (for example the aryl group) may be optionally substituted with one or more substituents selected from halo, oxo, hydroxy, amino, nitro, (1-6C)alkyl, (2-6C)alkenyl, (2-6C)alkynyl, (1-6C)haloalkyl, aryl, aryloxy, heteroaryl, heteroaryloxy, carbocyclyl and heterocyclyl.
37. The compound of any preceding claim, wherein R.sub.a is selected from (1-4C)alkyl, (2-4C)alkenyl, (2-4C)alkynyl, (1-4C)haloalkyl, (1-4C)alkoxy, aryl, aryloxy, heteroaryl, heteroaryloxy, carbocyclyl and heterocyclyl, any of which (for example the aryl group) may be optionally substituted with one or more substituents selected from halo, oxo, hydroxy, amino, nitro, (1-6C)alkyl, (1-6C)haloalkyl, aryl, aryloxy, heteroaryl and heteroaryloxy.
38. The compound of any preceding claim, wherein R.sub.a is selected from (1-4C)alkyl, (1-4C)haloalkyl, (1-4C)alkoxy, aryl, aryloxy, heteroaryl, heteroaryloxy, carbocyclyl and heterocyclyl, any of which (for example the aryl group) may be optionally substituted with one or more substituents selected from halo, oxo, hydroxy, amino, nitro, (1-6C)alkyl, (1-6C)haloalkyl, aryl, aryloxy, heteroaryl and heteroaryloxy.
39. The compound of any preceding claim, wherein R.sub.a is selected from aryl, aryloxy, heteroaryl, heteroaryloxy, carbocyclyl and heterocyclyl, any of which (for example the aryl group) may be optionally substituted with one or more substituents selected from halo, oxo, hydroxy, amino, nitro, (1-6C)alkyl, (1-6C)haloalkyl, aryl, aryloxy, heteroaryl and heteroaryloxy.
40. The compound of any preceding claim, wherein R.sub.a is selected from phenyl, phenoxy, 5-7 membered heteroaryl, 5-7 membered heteroaryloxy, 5-12 membered carbocyclyl and 5-12 membered heterocyclyl, any of which (for example the phenyl group) may be optionally substituted with one or more substituents selected from halo, oxo, hydroxy, amino, nitro, (1-5C)alkyl, (1-5C)haloalkyl, phenyl, phenoxy, heteroaryl and heteroaryloxy.
41. The compound of any preceding claim, wherein R.sub.a is selected from phenyl, 5-7 membered heteroaryl and 5-12 membered carbocyclyl, any of which (for example the phenyl group) may be optionally substituted with one or more substituents selected from halo, oxo, hydroxy, amino, nitro, (1-5C)alkyl, (1-5C)haloalkyl, phenyl, and heteroaryl.
42. The compound of any preceding claim, wherein R.sub.a is selected from phenyl and 5-12 membered carbocyclyl, any of which (for example the phenyl group) may be optionally substituted with one or more substituents selected from halo, hydroxy, amino, (1-5C)alkyl, (1-5C)haloalkyl, phenyl, and heteroaryl.
43. The compound of any preceding claim, wherein R.sub.a is selected from phenyl, cyclohexyl and adamantyl, any of which (for example the phenyl group) may be optionally substituted with one or more substituents selected from halo, (1-5C)alkyl, phenyl, and heteroaryl.
44. The compound of any preceding claim, wherein each R.sub.x is independently selected from hydrogen, (1-6C)alkyl, (1-6C)alkoxy and aryl, any of which may be optionally substituted with one or more substituents selected from halo, oxo, hydroxy, amino, nitro, (1-6C)alkyl and (1-6C)haloalkyl.
45. The compound of any preceding claim, wherein each R.sub.x is independently selected from hydrogen, (1-4C)alkyl, (1-4C)alkoxy and phenyl, any of which may be optionally substituted with one or more substituents selected from halo, amino and (1-6C)alkyl.
46. The compound of any preceding claim, wherein each R.sub.x is independently selected from hydrogen, (1-4C)alkyl, and phenyl, any of which may be optionally substituted with one or more substituents selected from halo, amino and (1-3C)alkyl.
47. The compound of any preceding claim, wherein each R.sub.x is phenyl.
48. The compound of any preceding claim, wherein n is 0, 1 or 2.
49. The compound of any preceding claim, wherein n is 0 or 1.
50. The compound of any preceding claim, wherein the compound is immobilized on a supporting substrate.
51. The compound of claim 50, wherein the supporting substrate is a solid.
52. The compound of claim 50 or 51, wherein the supporting substrate is selected from silica, alumina, zeolite and layered double hydroxide.
53. A process for the ring opening polymerisation (ROP) of a cyclic ester or a cyclic amide, the process comprising the step of: a) contacting a compound as defined in any preceding claim with one or more cyclic esters or cyclic amides.
54. The process of claim 53, wherein the one or more cyclic esters or cyclic amides has a structure according to formula (III) shown below: ##STR00025## wherein Q is selected from O or NR.sub.y, wherein R.sub.y is selected from hydrogen, (1-6C)alkyl, (2-6C)alkenyl and (2-6C)alkynyl; and ring A is a 4-23 membered heterocycle containing 1 to 4 O or N ring heteroatoms in total, wherein the heterocycle is optionally substituted with one or more substituents selected from oxo, (1-6C)alkyl, (2-6C)alkenyl, (2-6C)alkynyl, (1-6C)alkoxy, aryl and heteroaryl.
55. The process of claim 54, wherein Q is selected from O or NR.sub.y, wherein R.sub.y is selected from hydrogen, (1-3C)alkyl, (2-3C)alkenyl or (2-3C)alkynyl.
56. The process of claim 54 or 55, wherein Q is O.
57. The process of claim 54, 55 or 56, wherein ring A is a 4-18 membered heterocycle containing 1 to 3 O or N ring heteroatoms in total, wherein the heterocycle is optionally substituted with one or more substituents selected from oxo, (1-6C)alkyl, (1-6C)alkoxy and aryl.
58. The process of any one of claims 54 to 57, wherein ring A is a 4-, 6-, 7- or 16-membered heterocycle containing 1 to 3 O or N ring heteroatoms in total, wherein the heterocycle is optionally substituted with one or more substituents selected from oxo, (1-6C)alkyl, (1-6C)alkoxy and aryl.
59. The process of any one of claims 54 to 58, wherein ring A does not contain any N ring heteroatoms.
60. The process of any one of claims 53 to 59, wherein the cyclic ester or cyclic amide is a lactone.
61. The process of any one of claims 53 to 59, wherein the cyclic ester or cyclic amide is a lactide.
62. The process of any one of claims 53 to 58, wherein the cyclic ester or cyclic amide is a lactam.
63. The process of any one of claims 53 to 60, wherein the cyclic ester or cyclic amide is w-pentadecalactone
64. The process of any one of claims 53 to 63, wherein, in step a), the mole ratio of the compound of formula (I-A), (I-B) or (I-C) to the cyclic ester or cyclic amide is 1:50 to 1:10,000.
65. The process of any one of claims 53 to 64, wherein, in step a), the mole ratio of the compound of formula (I-A), (I-B) or (I-C) to the cyclic ester or cyclic amide is 1:150 to 1:5000.
66. The process of any one of claims 53 to 65, wherein, in step a), the mole ratio of the compound of formula (I-A), (I-B) or (I-C) to the cyclic ester or cyclic amide is 1:200 to 1:1000.
67. The process of any one of claims 53 to 66, wherein step a) is not conducted in a solvent.
68. The process of any one of claims 53 to 67, wherein step a) is conducted in a solvent selected from toluene, tetrahydrofuran and methylene chloride.
69. The process of any one of claims 53 to 68, wherein step a) is conducted for a period of 1 minute to 96 hours.
70. The process of any one of claims 53 to 69, wherein step a) is conducted for a period of 5 minute to 72 hours.
71. The process of any one of claims 53 to 70, wherein step a) is conducted at a pressure of 0.9 to 5 bar.
72. The process of any one of claims 53 to 71, wherein step a) is conducted at a pressure of 0.9 to 2 bar.
73. The process of any one of claims 53 to 72, wherein step a) is conducted in the presence of a chain transfer agent suitable for use in the ring opening polymerisation of a cyclic ester or cyclic amide.
74. The process of claim 73, wherein the chain transfer agent is a hydroxy-functional compound (e.g. an alcohol, diol or polyol).
75. Use of a compound as claimed in any preceding claim in the ring opening polymerisation (ROP) of a cyclic ester or a cyclic amide.
76. Use of claim 75, wherein the cyclic ester or amide is as defined in any one of claims 54 to 63.
Description
EXAMPLES
[0266] One or more examples of the invention will now be described, for the purpose of illustration only, with reference to the accompanying figures, in which:
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MATERIALS AND METHODS
[0337] All metal complexes were synthesized under anhydrous conditions, using MBraun gloveboxes and standard Schlenk techniques. Solvents and reagents were obtained from Sigma Aldrich or Strem and were used as received unless stated otherwise. THF and toluene were dried by refluxing over sodium and benzophenone and stored under nitrogen. ε-caprolactone and ω-pentadecalactone were dried over CaH.sub.2 and fractionally distilled under nitrogen before use. All dry solvents were stored under nitrogen and degassed by several freeze-pump-thaw cycles. NMR spectra were recorded using a Bruker AV 400 or 500 MHz spectrometer. Correlation between proton and carbon atoms were obtained by COSY, HSQC, and HMBC spectroscopic methods and subsequently assigned. MALDI-ToF analysis was carried out on a Waters MALDI Micro MX instrument in positive ion mode. Samples were prepared by dissolving the desired molecule (10 mg/ml) and matrix (dithranol, 10 mg/ml) in THF. This mixture was spotted onto the MALDI plate and allowed to dry. Due to a high degree of fragmentation and the formation of clusters, only the M.sup.+-O.sup.iPr value is reported for metal complexes. Elemental analysis was carried out by Mr. Stephen Boyer of the London Metropolitan University.
[0338] Crystals suitable for single crystal x-ray diffraction were grown either through slow evaporation of hexanes into THF or through low temperature crystallization in concentrated THF at −30° C. Samples were isolated in a glovebox under a pool of fluorinated oil and mounted on MiTeGen MicroMounts. The crystal was then cooled to 150 K with an Oxford Cryosystems Cryostream nitrogen cooling device. Data collection was carried out with an Oxford Diffraction Supernova diffractometer using Cu Kα (λ=1.5417 Å) or Mo Kα (λ=0.7107 Å) radiation. The resulting raw data was processed using CrysAlisPro. Structures were solved by SHELXT and Full-matrix least-squares refinements based on F.sup.2 were performed in SHELXL-14.sup.6, as incorporated in the WinGX package..sup.7 For each methyl group, the hydrogen atoms were added at calculated positions using a riding model with U(H)=1.5 Ueq (bonded carbon atom). The rest of the hydrogen atoms were included in the model at calculated positions using a riding model with U(H)=1.2 Ueq (bonded atom). Neutral atom scattering factors were used and include terms for anomalous dispersion..sup.8
Part A
Example 1—Ligand Synthesis
[0339] A variety of ligands, HL.sub.1-HL.sub.8, were prepared according to the general synthesis depicted in Scheme 1 shown below:
##STR00017##
Synthesis of HL.SUB.1
[0340] o-Vanillin (5 g, 32.9 mmol) was added to a round bottom flask and dissolved in ethanol (60 mL). 2,3,4,5,6-pentafluoroaniline (6.02 g, 32.9 mmol) was added into the stirring solution along with several drops of formic acid. This reaction mixture was refluxed for 72 hours resulting in a bright orange precipitate and a pale yellow solution. Precipitate was filtered, washed with ethanol (20 mL) and pentane (3×20 mL) and dried under vacuum. Crude product was then washed with hot ethanol (30 mL) and dried. Yield: 3.67 g (35%).sup.1H NMR (400 MHz, CDCl.sub.3) δ (ppm): 12.58 (s, 1H), 8.85 (s, 1H), 7.05 (m, 2H), 6.93 (t, 1H), 3.94 (s, 3H).
[0341]
Synthesis of HL.SUB.2
[0342] o-Vanillin (2.75 g, 18.0 mmol) was added to a round bottom flask and dissolved in ethanol (30 mL). Cyclohexylamine (1.79 g, 18.0 mmol) was syringed into the stirring solution along with several drops of formic acid. Reaction mixture was refluxed for 18 hours resulting in an orange solution. Volatiles were removed under vacuum yielding a viscus yellow oil. The oil was placed in a −30° C. freezer to solidify into a soft yellow solid. Yield: 3.85 g (91%).sup.1H NMR (400 MHz, CDCl.sub.3) δ (ppm): 8.29 (s, 1H), 6.88-6.82 (m, 2H), 6.73 (t, 1H), 3.87 (s, 3H), 3.28 (m, 1H), 1.81 (m, 4H), 1.62-1.32 (m, 6H).
[0343]
Synthesis of HL.SUB.3
[0344] o-Vanillin (3 g, 19.7 mmol) was added to a round bottom flask and dissolved in ethanol (30 mL). 2,6-dimethylaniline (2.34 g, 19.7 mmol) was syringed into the stirring solution along with several drops of formic acid. Reaction mixture was refluxed for 18 hours resulting in a yellow solution. Upon removal of several mL of ethanol under vacuum yellow solid precipitated from solution. This solid was filtered and washed with pentane (3×20 mL). The resulting dark yellow powder was dried to remove residual solvent. Yield: 3.57 g (71%).sup.1H NMR (400 MHz, CDCl.sub.3) δ (ppm): 13.5 (bs, 1H), 8.35 (s, 1H), 7.12 (m, 2H), 7.04 (m, 2H), 6.97 (m, 1H), 6.91 (t, 1H), 3.96 (s, 3H), 2.21 (s, 6H).
[0345]
Synthesis of HL.SUB.4
[0346] o-Vanillin (3 g, 19.7 mmol) was added to a round bottom flask and dissolved in ethanol (30 mL). 2,6-diisopropylaniline (3.5 g, 19.7 mmol) was syringed into the stirring solution along with several drops of formic acid. Reaction mixture was refluxed for 18 hours resulting in an orange solution. Upon cooling to room temperature copious amounts of large orange crystals formed. These crystals were filtered, washed with pentane (3×20 mL) and dried under vacuum. Yield: 5.0 g (82%).sup.1H NMR (400 MHz, CDCl.sub.3) δ (ppm): 13.5 (bs, 1H), 8.34 (s, 1H), 7.21 (m, 3H), 7.21-7.02 (m, 2H), 7.0 (t, 1H), 3.98 (s, 4H), 3.03, (sep, 2H), 1.20 (d, 12H).
[0347]
Synthesis of HL.SUB.5
[0348] o-Vanillin (5 g, 32.9 mmol) was added to a round bottom flask and dissolved in ethanol (25 mL). 2-aminobiphenyl (5.56 g, 32.9 mmol) was added to the stirring solution along with several drops of formic acid. The reaction mixture was refluxed for 24 hours resulting in a deep red solution. Volatiles were removed under vacuum. Yield: 8.06 g (81%). .sup.1H NMR (400 MHz, CDCl.sub.3) δ (ppm): 12.9 (1H, bs), 8.60 (s, 1H), 7.43-7.36 (m, 8H), 7.22 (d, 1H), 6.96 (m, 2H), 6.86 (t, 1H), 3.88 (s, 3H).
[0349]
Synthesis of HL.SUB.6
[0350] o-Vanillin (3 g, 19.7 mmol) was added to a round bottom flask and dissolved in ethanol (30 mL). Adamantan-1-amine (2.98 g, 19.7 mmol) was then added to the stirring solution along with several drops of formic acid. Reaction mixture was refluxed for 20 hours resulting in an orange solution. Volatiles were removed under vacuum yielding an orange solid which was washed with pentane (20 mL×3) Yield: 3.67 g, (65%).sup.1H NMR (400 MHz, CDCl.sub.3) δ (ppm): 15.16 (bs, 1H), 8.25 (s, 1H), 6.85 (m, 2H), 6.69 (t, 1h), 3.88 (s, 3H), 2.19 (m, 3H), 1.85 (d, 6H), 1.73 (m, 6H).
[0351]
Synthesis of HL.SUB.7
[0352] o-Vanillin (1.5 g, 9.86 mmol) was added to a round bottom flask and dissolved in ethanol (30 mL). 2,4,6-tritertbutylaniline (2.58 g, 9.86 mmol) was added into the stirring solution along with several drops of formic acid. Reaction mixture was refluxed for 18 hours resulting in an orange solution. Volatiles were removed under vacuum to yield a yellow solid which was recrystallized from hot ethanol (30 mL). The pure yellow crystalline product was washed with cold pentane (20 mL×3) and dried under vacuum. Yield: 2.8 g (71%).sup.1H NMR (400 MHz, CDCl.sub.3) δ (ppm): 13.8 (s, 1H), 8.24 (s, 1H), 7.41 (s, 2H), 7.03 (m, 1H), 6.91 (m, 2H), 3.97 (s, 3H), 1.35 (s, 9H), 1.34 (s, 18H).
[0353]
Synthesis of HL.SUB.8
[0354] o-Vanillin (1.5 g, 9.86 mmol) was added to a round bottom flask and dissolved in ethanol (30 mL). tritylamine (2.56 g, 9.86 mmol) was added into the stirring solution along with several drops of formic acid. This reaction mixture was refluxed for 24 hours resulting in a bright yellow precipitate and a pale yellow solution. Precipitate was filtered, washed with ethanol (30 mL) and pentane (3×20 mL) and dried under vacuum. Yield: 3.65 g (94%).sup.1H NMR (400 MHz, CDCl.sub.3) δ (ppm): 14.8 (s, 1H), 7.97 (s, 1H), 7.35-7.23 (m, 15H), 6.98 (dd, 1H), 6.82 (t, 1H), 6.78 (m, 1H), 3.97 (s, 3H).
[0355]
Example 2—Complex Synthesis
[0356] Using ligands HL.sub.1-HL.sub.8 prepared in Example 1, a variety of complexes, (L.sub.1).sub.2Ti(O.sup.iPr).sub.2-(L.sub.8).sub.2Ti(O.sup.iPr).sub.2, were prepared according to the general synthesis depicted in Scheme 2 shown below:
##STR00018##
[0357] The o-vanillin derived ligands were found to possess two separate modes of coordination to the metal: 6-membered N,O coordination, and 5-membered O,O coordination. These two coordination modes were found to be independent of one another, thus the eight catalysts synthesized each exhibit one of three basic types of coordination chemistries found to be possible in these systems. Type A: N,O:N,O coordination, Type B: N,O:O,O coordination, Type C: O,O:O,O coordination. Within each type there are also additional isomers that are theoretically possible. Upon increasing steric bulk, coordination around the metal centre rearranges from: Type A-I to Type A-II, then to Type B followed by Type C. (Scheme 3).
##STR00019##
Synthesis of (L.sub.1).sub.2Ti(O.sup.iPr).sub.2
[0358] HL.sub.1 (0.50 g, 1.58 mmol) and Ti(O.sup.iPr).sub.4 (0.224 g, 0.79 mmol) were dissolved separately in toluene (7 mL and 3 mL, respectively), and cooled to −30° C. in a glovebox freezer. The two solutions were then mixed and allowed to stir for 18 hours. Volatiles were removed in vacuo yielding a bright orange solid. Yield: 316 mg (50%) MALDI-TOF MS (m/z): 739.64 (calc. for [M.sup.+-O.sup.iPr=739.077]).sup.1H NMR (400 MHz, CDCl.sub.3) δ (ppm): 8.23 (bs, 2H), 7.16 (bm, 4H), 6.93 (t, 2H), 4.88 (m, 2H), 3.82 (s, 6H), 1.17 (d, 12H). .sup.13C{.sup.1H} (125 MHz, CDCl.sub.3) δ (ppm): 171.4, 156.4, 149.5, 141.7, 139.3, 137.3, 136.4, 127.7, 126.2, 121.1, 117.3, 80.7, 56.3, 25.1 C.sub.34H.sub.28F.sub.10N.sub.2O.sub.6Ti (798.45 g/mol) Calculated: C, 51.15; H, 3.53; N, 3.51%. Found: C, 51.03; H, 3.39; N, 3.66%.
[0359]
[0360]
[0361]
Synthesis of (L.sub.2).sub.2Ti(O.sup.iPr).sub.2
[0362] HL.sub.2 (0.30 g, 1.29 mmol) and Ti(O.sup.iPr).sub.4 (0.183 g, 0.643 mmol) were dissolved separately in toluene (15 mL and 5 mL, respectively), and cooled to −30° C. in a glovebox freezer. The two solutions were then mixed and allowed to stir for 24 hours turning from yellow to light orange. Volatiles were removed in vacuo and hexane (30 mL) was added to the resulting orange-yellow wax. Crude mixture was recrystallized from a minimum of THF in a −30° C. freezer. Crude Yield: 332 mg (82%) MALDI-TOF MS (m/z): 571.3003 (calc. for [M.sup.+-O.sup.iPr=571.2651]).sup.1H NMR (400 MHz, CDCl.sub.3) δ (ppm): 8.10 (bs, 2H), 6.87 (m, 2H), 6.81 (m, 2H), 6.67 (t, 2H), 3.86 (s, 6H), 2.07 (m, 2H), 1.85-0.88 (m, 30H), 0.36 (m, 2H). C.sub.34H.sub.50N.sub.2O.sub.6Ti (630.65 g/mol) Calculated: C, 64.75; H, 7.99; N, 4.44%. Found: C, 64.90; H, 8.05; N, 4.32%.
[0363]
[0364]
Synthesis of (L.sub.3).sub.2Ti(O.sup.iPr)
[0365] HL.sub.3 (0.246 g, 0.964 mmol) and Ti(O.sup.iPr).sub.4 (0.137 g, 0.482 mmol) were dissolved separately in toluene (15 mL and 5 mL, respectively), and cooled to −30° C. in a glovebox freezer. The two solutions were then mixed and allowed to stir for 24 hours. Volatiles were removed in vacuo and hexane (10 mL) was added to the resulting orange-yellow wax. This hexane was removed under vacuum to provide the final complex as a bright orange powder. Yield: 327 mg (99%). MALDI-TOF MS (m/z): 615.3101 (calc. for [M.sup.+-O.sup.iPr=615.2338]).sup.1H NMR (400 MHz, CDCl.sub.3) δ (ppm): 8.18 (s, 2H), 7.3 (m, 1H)*, 6.91-6.86 (m, 9H), 6.70 (t, 2H), 4.82 (m, 2H), 4.00 (s, 6H), 2.14 (s, 12H), 1.11 (d, 12H) .sup.13C{.sup.1H} (125 MHz, CDCl.sub.3) δ (ppm): 156.2, 151.6, 149.5, 129.0, 128.7, 128.2, 127.6, 124.0, 121.9, 116.6, 80.1, 56.8, 25.4, 18.5 C.sub.38H.sub.46N.sub.2O.sub.6Ti (674.28 g/mol) Calculated: C, 67.65; H, 6.87; N, 4.15%. Found: C, 67.42; H, 6.89; N, 4.22%.
[0366]
[0367]
[0368]
Synthesis of (L.sub.4).sub.2Ti(O.sup.iPr)
[0369] HL.sub.4 (0.30 g, 0.946 mmol) and Ti(O.sup.iPr).sub.4 (0.137 g, 0.482 mmol) were dissolved separately in toluene (15 mL and 5 mL, respectively), and cooled to −30° C. in a glovebox freezer. The two solutions were then mixed and allowed to stir for 24 hours. Volatiles were removed in vacuo and hexane (10 mL) was added to the resulting orange-yellow wax. This hexane was removed under vacuum to provide the final complex as a bright orange powder. Yield: 176 mg (46%) MALDI-TOF MS (m/z): 727.5702 (calc. for [M.sup.+-O.sup.iPr=727.3590]).sup.1H NMR (400 MHz, CDCl.sub.3) δ (ppm): 8.59 (s, 2H), 7.67 (bs, 2H), 7.15 (m, 6H), 6.91 (d, 2H), 6.80 (t, 2H), 4.76 (m, 2H), 3.97 (s, 6H), 3.10 (bs, 4H), 1.19-1.15 (d, 38H) .sup.13C{.sup.1H} (125 MHz, CDCl.sub.3) δ (ppm): 159.9, 155.7, 150.0, 149.6, 138.3, 122.9, 121.9, 120.9, 117.3, 112.9, 80.6, 56.9, 27.8, 25.5, 23.7. C.sub.46H.sub.62N.sub.2O.sub.6Ti (786.9 g/mol): Calculated: C, 70.22; H, 7.94; N, 3.56%. Found: C, 70.17; H, 8.02; N, 3.56%.
[0370]
[0371]
[0372]
Synthesis of (L.sub.5).sub.2Ti(O.sup.iPr)
[0373] HL.sub.5 (2 g, 6.60 mmol) and Ti(O.sup.iPr).sub.4 (0.937 g, 3.30 mmol) were dissolved separately in toluene (15 mL and 5 mL, respectively), and cooled to −30° C. in a glovebox freezer. The two solutions were then mixed and allowed to stir for 24 hours. Volatiles were removed in vacuo yielding an amber solid. Crude mixture was recrystallized by layering hexanes and THF. Yield: 2.28 g (89%). MALDI-TOF MS (m/z): 712.2714 (calc. for [M.sup.+-O.sup.iPr]=711.2338).sup.1H NMR (400 MHz, CDCl.sub.3) δ (ppm): 8.36 (bs, 2H), 7.23 (m, 18H), 6.78 (bm, 2H), 6.60 (m, 2H), 4.87 (bm, 2H), 3.71 (s, 6H), 1.17 (m, 12H).
[0374]
Synthesis of (L.sub.6).sub.2Ti(O.sup.iPr)
[0375] HL.sub.6 (1.193 g, 3.03 mmol) and Ti(O.sup.iPr).sub.4 (0.429 g, 1.51 mmol) were dissolved separately in toluene (15 mL and 5 mL, respectively), and cooled to −30° C. in a glovebox freezer. The two solutions were then mixed and allowed to stir for 24 hours. Volatiles were removed in vacuo yielding a light yellow powder. Crude mixture was recrystallized by layering hexanes and THF. Yield: 1.29 g (90%) MALDI-TOF MS (m/z): 675.9662 (calc. for [M.sup.+-O.sup.iPr]=675.3277).sup.1H NMR (400 MHz, CDCl.sub.3) δ (ppm): 8.77 (s, 2H), 7.54 (dd, 2H), 6.72 (m, 4H), 4.90 (m, 2), 3.77 (s, 6H), 2.16 (s, 6H). 1.85 (s, 12H), 1.73 (m, 12H), 1.33 (d, 12H). .sup.13C{.sup.1H} (125 MHz, CDCl.sub.3) δ (ppm): 154.1, 152.1, 149.3, 123.0, 120.1, 117.5, 111.1, 80.3, 57.9, 57.0, 43.4, 36.7, 29.8, 25.5.
[0376]
[0377]
[0378]
Synthesis of (L.sub.7).sub.2Ti(O.sup.iPr)
[0379] HL.sub.7 (0.40 g, 1.01 mmol) and Ti(O.sup.iPr).sub.4 (0.144 g, 0.51 mmol) were dissolved separately in toluene (7 mL and 3 mL, respectively), and cooled to −30° C. in a glovebox freezer. The two solutions were then mixed and allowed to stir for 18 hours. Volatiles were removed in vacuo yielding an orange solid. Yield: 176 mg (46%) MALDI-TOF MS (m/z): 896.6176 (calc. for [M.sup.+-O.sup.iPr]=895.5468).sup.1H NMR (400 MHz, CDCl.sub.3) δ (ppm): 8.71 (s, 2H), 7.82 (m, 2H), 7.39 (s, 4H), 6.84 (m, 4H), 4.60 (m, 2H), 3.82 (s, 6H), 1.37 (s, 36H), 1.35 (s, 18H), 1.11 (d, 12H). .sup.13C{.sup.1H} (125 MHz, CDCl.sub.3) δ (ppm): 157.8, 155.3, 151.4, 149.9, 143.6, 138.4, 121.7, 120.7, 117.7, 111.7, 80.7, 56.9, 36.0, 34.8, 31.7 31.5, 25.5. C.sub.58H.sub.86N.sub.2O.sub.6Ti (955.20 g/mol) Calculated: C, 72.93; H, 9.08; N, 2.93%. Found: C, 72.81; H, 9.17; N, 3.12%.
[0380]
[0381]
[0382]
Synthesis of (L.sub.8).sub.2Ti(O.sup.iPr)
[0383] HL.sub.8 (2.04 g, 5.18 mmol) was suspended in toluene (20 mL) and THF (5 mL) and Ti(O.sup.iPr).sub.4 (0.736 g, 2.59 mmol) dissolved in toluene (5 mL) was added dropwise. The yellow suspension cleared after several minutes of stirring and allowed to react for 24 hours. Volatiles were removed in vacuo yielding a light yellow solid. Yield: 2.32 (94%) MALDI-TOF MS (m/z): 891.3367 (calc. for [M.sup.+-O.sup.iPr]=891.3277).sup.1H NMR (400 MHz, CDCl.sub.3) δ (ppm): 8.40 (s, 2H), 7.91 (dd, 2H), 7.32-7.23 (m, 30H), 6.72 (m, 4H), 4.59 (m, 2H), 3.64 (s, 6H), 1.06 (d, 12H). .sup.13C{.sup.1H} (125 MHz, CDCl.sub.3) δ (ppm): 156.2, 154.8, 149.3, 146.4, 129.9, 127.6, 126.6, 125.3, 122.5, 120.3, 117.4, 111.1, 80.3, 78.4, 56.9, 25.5. C.sub.60H.sub.58N.sub.2O.sub.6Ti (951.00 g/mol) Calculated: C, 75.78; H, 6.15; N, 2.95%. Found: C, 75.88; H, 6.24; N, 3.03%.
[0384]
[0385]
[0386]
[0387] Using ligands HL.sub.2 and HL.sub.3 prepared in Example 1, complexes (L.sub.2).sub.2ZrCl.sub.2 and (L.sub.3).sub.2ZrCl.sub.2 were prepared according to the general synthesis depicted in Scheme 4 shown below
##STR00020##
Synthesis of (L.sub.2).sub.2ZrCl.sub.2
[0388] HL.sub.2 (0.40 g, 1.71 mmol) and K[N(SiMe.sub.3).sub.2] (0.342 g, 1.71 mmol) were dissolved separately in THF (5 mL and 3 mL, respectively). The K[N(SiMe.sub.3).sub.2] solution was then added dropwise to the stirring solution of ligand and allowed to react for 24 hours. ZrCl.sub.4(THF).sub.2 (0.323 g, 0.857 mmol) was dissolved in THF (5 mL) and added to the deprotonated ligand. After stirring for 24 hours the resulting cloudy yellow solution was centrifuged and the solution was decanted. Volatiles were removed in vacuo and hexane (10 mL) was added to the resulting yellow wax. This hexane was removed under vacuum to provide the final complex as a light powder. MALDI-TOF MS (m/z): 589.1416 (calc. for [M.sup.+-Cl=589.1411]).sup.1H NMR (400 MHz, CDCl.sub.3) δ (ppm): 8.18 (s, 2H), 7.06 (m, 2H), 6.89 (t, 2H), 6.87 (m, 2H), 4.16 (m, 2H), 3.98 (s, 6H), 3.74 (m, 4H, THF), 1.85 (m, 4H, THF), 1.59-1.07 (bm, 20H). Calculated: C, 53.66; H, 5.79; N, 4.47%. C, 53.78; H, 5.80; N, 4.31%.
[0389]
Synthesis of (L.sub.3).sub.2ZrCl.sub.2
[0390] HL.sub.3 (0.246 g, 0.964 mmol) and K[N(SiMe.sub.3).sub.2] (0.192 g, 0.964 mmol) were dissolved separately in THF (5 mL and 3 mL, respectively). The K[N(SiMe.sub.3).sub.2] solution was then added dropwise to the stirring solution of ligand and allowed to react for 24 hours. ZrCl.sub.4(THF).sub.2 (0.182 g, 0.482 mmol) was dissolved in THF (5 mL) and added to the deprotonated ligand. After stirring for 24 hours the resulting cloudy yellow solution was centrifuged and the solution was decanted. Volatiles were removed in vacuo and hexane (10 mL) was added to the resulting yellow wax. This hexane was removed under vacuum to provide a light powder, which could be recrystallized by layering of hexanes and THF. Yield: 0.282 mg, 87.3%. MALDI-TOF MS (m/z): 633.1627 (calc. for [M.sup.+-Cl=633.1098]).sup.1H NMR (400 MHz, CDCl.sub.3) δ (ppm): 8.33 (s, 2H), 7.09 (m, 6H), 7.06 (d, 2H), 7.0 (d, 2H), 6.90 (t, 2H), 3.78 (s, 6H), 2.45 (s, 12H).
[0391]
Example 3—Crystallographic Studies
[0392] Table 1 below provides a summary of the T-O distances in complexes (L.sub.1).sub.2Ti(O.sup.iPr).sub.2-(L.sub.8).sub.2Ti(O.sup.iPr).sub.2.
TABLE-US-00001 TABLE 1 Summary of T-O distances in complexes (L.sub.1).sub.2Ti(O.sup.iPr).sub.2—(L.sub.8).sub.2Ti(O.sup.iPr).sub.2 Ti—O.sup.iPr(1) Ti—O.sup.iPr(2) Coordination Compound Dist. (Å) Dist. (Å) Type (L.sub.1).sub.2Ti(O.sup.iPr).sub.2 1.847(2) 1.834(2) A-I (L.sub.2).sub.2Ti(O.sup.iPr).sub.2* 1.77 1.81 A-I (L.sub.3).sub.2Ti(O.sup.iPr).sub.2 1.795(1) 1.803(1) A-II (L.sub.4).sub.2Ti(O.sup.iPr).sub.2 1.77 1.786(2) B (L.sub.5).sub.2Ti(O.sup.iPr).sub.2 1.787(1) 1.800(1) B (L.sub.6).sub.2Ti(O.sup.iPr).sub.2 1.760(2) 1.785(2) C (L.sub.5).sub.2Ti(O.sup.iPr).sub.2 1.758(2) 1.776(2) C (L.sub.8).sub.2Ti(O.sup.iPr).sub.2 1.774(2) 1.780(2) C *An average is given between the two enantiomers in the asymmetric unit
[0393] Table 2 below provides select crystallographic details for (L.sub.1).sub.2Ti(O.sup.iPr).sub.2-(L.sub.4).sub.2Ti(O.sup.iPr).sub.2.
TABLE-US-00002 TABLE 2 Select crystallographic details for (L.sub.1).sub.2Ti(O.sup.iPr).sub.2—(L.sub.4).sub.2Ti(O.sup.iPr).sub.2 Compound (L.sub.1).sub.2Ti(O.sup.iPr).sub.2 (L.sub.2).sub.2Ti(O.sup.iPr).sub.2 (L.sub.3).sub.2Ti(O.sup.iPr).sub.2 (L.sub.4).sub.2Ti(O.sup.iPr).sub.2 Chemical formula C.sub.34H.sub.28F.sub.10N.sub.2O.sub.6Ti C.sub.37H.sub.57N.sub.2O.sub.6Ti C.sub.38H.sub.46N.sub.2O.sub.6Ti C.sub.46H.sub.62N.sub.2O.sub.6Ti Formula weight 798.48 673.74 674.67 786.87 Temp (K) 150(2) 150(2) 150(2) 150(2) Space group Triclinic, P-1 Triclinic, P-1 Triclinic, P-1 Orthorhombic, Pna2.sub.1 a (Å) 13.7054(3) 10.9508(3) 10.2329(3) 23.3761(6) b (Å) 14.1810(4) 13.4552(4) 10.4196(2) 13.2107(3) c (Å) 19.1110(5) 14.3513(4) 18.4022(5) 14.8217(4) α (°) 110.121(2) 103.976(3) 79.916(2) β (°) 102.985(2) 105.987(2) 79.572(2) γ (°) 91.205(2) 109.032(3) 66.375(2) V (Å.sup.3) 3378.78(16) 1790.69(10) 1755.88(8) 4577.2(2) Z 4 2 2 4 D.sub.calcd (Mg/m.sup.3) 1.570 1.250 1.275 1.142 Crystal size (mm) 0.27 × 0 20 × 0.08 0.25 × 0.20 × 0.06 0.25 × 0.25 × 0.15 0.25 × 0.15 × 0.08 Theta range for 3.555 to 76.329 3.732 to 76.089 4.653 to 78.178 3.843 to 76.405 data collection (°) μ (mm.sup.−1) (Cu, Kα) 3.093 (Cu, Kα) 2.394 (Cu, Kα) 2.449 (Cu, Kα) 1.944 Reflections collected 51454 26538 38003 51906 Unique reflections 13998 [R.sub.int = 0.0293] 7376 [R.sub.int = 0.0365] 7295 [R.sub.int = 0.0276] 8674 [R.sub.int = 0.8505] Data Completeness 100.0% [67.684] 100.0% [67.684] 100.0% [67.684] 100.0% [67.684] to [θ] Data/restraints/ 13998/12/979 7376/0/422 7296/0/434 8674/45/533 parameters R1.sup.a (%) (all data) 3.00 (3.50) 4.44 (5.22) 3.04 (3.21) 4.20 (4.80) wR2.sup.b (%)(all data) 7.75 (8.07) 12.55 (13.38) 8.41 (8.55) 10.70 (11.36) Goodness-of-fit on F.sup.2 1.025 1.082 1.047 1.025 Largest diff. peak and 0.334 and −0.380 1.187 and −0.411 0.254 and −0.379 0.396 and −0.409 hole (e Å.sup.−3) .sup.aR1 = Σ | |F.sub.o| − |F.sub.c| |/Σ |F.sub.o| × 100 .sup.bwR2 = [Σ w(F.sub.o.sup.2 − F.sub.c.sup.2).sup.2/Σ (w|F.sub.o|.sup.2).sup.2].sup.1/2 × 100
[0394] Table 3 below select crystallographic details for (L.sub.5).sub.2Ti(O.sup.iPr).sub.2-(L.sub.8).sub.2Ti(O.sup.iPr).sub.2.
TABLE-US-00003 TABLE 3 Select crystallographic details for (L.sub.5).sub.2Ti(O.sup.iPr).sub.2—(L.sub.8).sub.2Ti(O.sup.iPr).sub.2 Compound (L.sub.5).sub.2Ti(O.sup.iPr).sub.2 (L.sub.6).sub.2Ti(O.sup.iPr).sub.2 (L.sub.7).sub.2Ti(O.sup.iPr).sub.2 (L.sub.8).sub.2Ti(O.sup.iPr).sub.2 Chemical formula C.sub.46H.sub.46N.sub.2O.sub.5Ti C.sub.42H.sub.58N.sub.2O.sub.6Ti C.sub.66H.sub.102N.sub.2O.sub.8Ti C.sub.63H.sub.65N.sub.2O.sub.6Ti Formula weight 770.75 734.80 1099.39 994.07 Temp (K) 150( ) 150(2) 150(2) 150(2) Space group Monoclinic, P2.sub.1/n Monoclinic, P2.sub.1/c Monoclinic, P2.sub.1/c Triclinic, P-1 a (Å) 16.0712(4) 22.6717(4) 19.6212(3) 9.3703(5) b (Å) 9.9873(2) 14.4902(2) 17.3312(3) 16.9578(10) c (Å) 25.2051(5) 12.0146(2) 19.3123(3) 18.9044(15) α (°) 67.887(7) β (°) 94.390(2) 91.2620(10) 95.4930(10) 86.252(5) γ (°) 75.730(5) V (Å.sup.3) 4033.75(15) 3946.05(11) 6537.16(18) 2695.8(3) Z 4 4 4 2 D.sub.calcd (Mg/m.sup.3) 1.268 1.237 1.117 1.225 Crystal size (mm) 0.30 × 0.15 × 0.08 0.25 × 0.25 × 0.18 0.25 × 0.22 × 0.15 0.25 × 0.20 × 0.06 Theta range for data 3.517 to 76.264 3.620 to 76.238 3.434 to 76.282 3.307 to 30.439 collection (°) μ (mm.sup.−1) (Co, Kα) 2.203 (Cu, Kα) 2.218 (Cu, Kα) 1.510 (Mo, Kα) 0.212 Reflections collected 25700 36803 50743 27281 Unique reflections 8359 [R.sub.int = 0.0335] 8213 [R.sub.int = 0.0305] 13578 [R.sub.int = 0.0336] 13947 [R.sub.int = 0.0600] Data Completeness 100.0% [67.684] 100.0% [67.684] 100.059 [67.684] 99.7% [25.000] to [θ] Data/restraints/ 8359/0/502 8213/26/496 13570/167/846 13947/96/734 parameters R1.sup.a (%) (all data) 3.53 (4.41) 4.58 (5.03) 4.85 (6.08) 7.33 (16.63) wR2.sup.b (%)(all data) 8.84 (9.48) 12.53 (12.99) 13.59 (14.69) 11.65 (14.90) Goodness-of-fit on F.sup.2 1.020 1.028 1.039 1.003 Largest diff. peak and 0.259 and −0.334 0.733 and −0.476 0.454 and −0.524 9.324 and −0.396 hole (e Å.sup.−3) .sup.aR1 = Σ | |F.sub.o| − |F.sub.c| |/Σ |F.sub.o| × 100 .sup.bwR2 = [Σ w(F.sub.o.sup.2 − F.sub.c.sup.2).sup.2/Σ (w|F.sub.o|.sup.2).sup.2].sup.1/2 × 100
Example 4—NMR Studies
[0395] Evidence of different isomers in solution can be seen by following the .sup.1H NMR spectra of each type. For (L.sub.1).sub.2Ti(O.sup.iPr).sub.2, which has Type A-I coordination, the imine CH resonance shifts up field by 0.67 ppm, relative to the parent ligand, and broadens significantly. (
Example 5—Variable Temperature NMR
[0396] To better understand the nature of intermediate case of Type B catalysts, variable temperature NMR experiments were undertaken on (L.sub.4).sub.2Ti(O.sup.iPr).sub.2. As Type B coordination shows both N,O and O,O chelation, but only shows a single imine resonance, it was necessary to confirm that the asymmetry observed in the solid state structure remains in solution. (
[0397] Upon heating (L.sub.4).sub.2Ti(O.sup.iPr).sub.2 in d.sup.2-1,1,2,2-tetrachloroethane (TCE) incrementally from room temperature to 100° C., peaks sharpened slightly but did not shift (
Example 6—Polymerisation Studies
Caprolactone Polymerisation
[0398] The general polymerisation conditions were as follows: In a glovebox, catalyst was weighed (˜7 mg) into a vial, dissolved in ε-caprolactone and, in cases where the reaction was not run neat, enough toluene to produce a 1 M solution in lactone. The vial was sealed and the stirring solution was immersed in an oil bath preheated to 80° C. After the desired time samples were cooled to 0° C., exposed to air and aliquots of the crude reaction mixture were taken for analysis by .sup.1H NMR in CDCl.sub.3. Volatiles were removed under vacuum and a 10 mg/mL THF solution was prepared for GPC. The conversion of ε-CL to PCL was determined by integration of the methylene proton peaks of the .sup.1H NMR spectra, δ 4.30-3.95.
[0399] ε-caprolactone was chosen to initially test the newly synthesized family of catalysts towards the ROP of lactones. Polymerizations were conducted both in toluene solution (1:200 [I]:[ε-CL], 1 M [ε-CL]; Table 4) and under neat conditions (1:200 [I]:[ε-CL] or 1:1000 [I]:[ε-CL]; Table 5). Catalysts (L.sub.1).sub.2Ti(O.sup.iPr).sub.2 and (L.sub.2).sub.2Ti(O.sup.iPr).sub.2 were capable of polymerization under both conditions. After 24 hours, however both (L.sub.1).sub.2Ti(O.sup.iPr).sub.2 and (L.sub.2).sub.2Ti(O.sup.iPr).sub.2 had reached full conversion, indicating a significant initiation period.
[0400] (L.sub.4-8).sub.2Ti(O.sup.iPr).sub.2 are all active initiators and are, in some cases, several times faster than (L.sub.1,2).sub.2Ti(O.sup.iPr).sub.2. (L.sub.4).sub.2Ti(O.sup.iPr).sub.2 reached full conversion to PCL within four hours, while (L.sub.6-8).sub.2Ti(O.sup.iPr).sub.2 reached full conversion in just two. In each case the resulting PCL shows a monomodal distribution in the GPC trace with narrow PDIs. Experimental M.sub.n were in good agreement with calculated values when accounting for two growing PCL chains per Ti centre. All catalysts polymerize CL in a living manner, with M.sub.n increasing with reaction time while maintaining narrow PDI.
[0401] Interestingly, the order of reactivity follows the trend (L.sub.8).sub.2Ti(O.sup.iPr).sub.2˜(L.sub.7).sub.2Ti(O.sup.iPr).sub.2˜(L.sub.6).sub.2Ti(O.sup.iPr).sub.2>(L.sub.5).sub.2Ti(O.sup.iPr).sub.2˜(L.sub.4).sub.2Ti(O.sup.iPr).sub.2>(L.sub.3).sub.2Ti(O.sup.iPr).sub.2>(L.sub.2).sub.2Ti(O.sup.iPr).sub.2˜(L.sub.1).sub.2Ti(O.sup.iPr).sub.2 or, written in terms of coordination chemistry, Type C>Type B>Type A-II>Type A-I. The reasons for this trend can be explained by examining the crowding around the metal centre. Type C complexes possess bulkier R groups, however this bulk is pushed distal to the metal centre and actually results in less steric crowding around the Ti than Type A-I. This more open coordination environment causes an increase in rate through the coordination insertion mechanism.
TABLE-US-00004 TABLE 4 Polymerisation of ε-caprolactone in toluene Time Conv. M.sub.n M.sub.n Coordination Entry Catalyst.sup.a (h) (%).sup.b (exp).sup.c (calc).sup.d Ð Type 1 (L.sub.1).sub.2Ti(O.sup.iPr).sub.2 4 32 — — — A-I 2 (L.sub.1).sub.2Ti(O.sup.iPr).sub.2 24 99 9,460 11,300 1.13 A-I 3 (L.sub.2).sub.2Ti(O.sup.iPr).sub.2 4 — — — — A-I 4 (L.sub.2).sub.2Ti(O.sup.iPr).sub.2 24 99 8,780 11,300 1.20 A-I 5 (L.sub.3).sub.2Ti(O.sup.iPr).sub.2 9 90 8,890 10,270 1.27 A-II 6 (L.sub.3).sub.2Ti(O.sup.iPr).sub.2 24 99 15,200 11,300 1.47 A-II 7 (L.sub.4).sub.2Ti(O.sup.iPr).sub.2 4 99 13,090 11,300 1.27 B 8 (L.sub.5).sub.2Ti(O.sup.iPr).sub.2 3 61 9,060 7,000 1.09 B 9 (L.sub.5).sub.2Ti(O.sup.iPr).sub.2 4 73 10,940 8,330 1.10 B 10 (L.sub.6).sub.2Ti(O.sup.iPr).sub.2 2 99 16,113 11,300 1.47 C 11 (L.sub.7).sub.2Ti(O.sup.iPr).sub.2 2 99 13,100 11,300 1.09 C 12 (L.sub.8).sub.2Ti(O.sup.iPr).sub.2 2 99 12,200 11,300 1.27 C .sup.a1M ε-CL in toluene, 80° C., N.sub.2, 0.5 mol % .sup.bCalculated by .sup.1H NMR of the methylene region. .sup.cMeasured by GPC relative to polystyrene standard and corrected by a factor of 0.56 .sup.dM.sub.n(calc) = (conversion/100) × loading/[2 Growing Chains] × RMM(εCL) .sup.eTOF = (conversion/100) × loading/(time × 2 growing chains)
TABLE-US-00005 TABLE 5 Polymerisation of ε-caprolactone in neat ε-caprolactone Catalyst Time Conv. M.sub.n M.sub.n TOF Entry (mol %).sup.a (m) (%).sup.b (exp).sup.c (calc).sup.d Ð (h.sup.−1).sup.e 1 (L.sub.1).sub.2Ti(O.sup.iPr).sub.2 (0.5%) 60 17 2,120 1,940 1.10 34 2 (L.sub.1).sub.2Ti(O.sup.iPr).sub.2 (0.1%) 60 2 — — — — 3 (L.sub.2).sub.2Ti(O.sup.iPr).sub.2 (0.5%) 20 0 — — — — 4 (L.sub.2).sub.2Ti(O.sup.iPr).sub.2 (0.5%) 1,260 56 17,130 6,390 1.37 5 5 (L.sub.3).sub.2Ti(O.sup.iPr).sub.2 (0.5%) 60 24 5,510 2,740 1.05 48 6 (L.sub.3).sub.2Ti(O.sup.iPr).sub.2 (0.1%) 60 7 4,330 4,000 1.06 70 7 (L.sub.4).sub.2Ti(O.sup.iPr).sub.2 (0.5%) 20 24 3,980 2,740 1.09 138 8 (L.sub.4).sub.2Ti(O.sup.iPr).sub.2 (0.5%) 80 71 12,570 8,100 1.12 106 9 (L.sub.4).sub.2Ti(O.sup.iPr).sub.2 (0.1%) 60 31 17,810 17,690 1.04 310 10 (L.sub.7).sub.2Ti(O.sup.iPr).sub.2 (0.5%) 50 90 15,440 10,270 1.28 216 11 (L.sub.7).sub.2Ti(O.sup.iPr).sub.2 (0.1%) 60 40 35,390 22,820 1.05 400 12 (L.sub.8).sub.2Ti(O.sup.iPr).sub.2 (0.5%) 50 71 16,060 8,104 1.17 170 13 (L.sub.8).sub.2Ti(O.sup.iPr).sub.2 (0.1%) 50 44 37,430 25,110 1.06 440 .sup.aNeat ε-CL, 80° C., N.sub.2 .sup.bCalculated by .sup.1H NMR of the methylene region, stirring restricted by increased viscosity at high conversion. .sup.cMeasured by GPC relative to polystyrene standard and corrected by a factor of 0.56 .sup.dM.sub.n(calc) = (conversion/100) × loading/[2 growing chains] × RMM(εCL) .sup.eTOF = (conversion/100) × loading/(time × 2 growing chains)
Caprolactone Kinetic Studies
[0402] The general polymerisation conditions for analysing the ε-caprolactone kinetics were as follows: In a glovebox, catalyst was weighed (0.025 mmol, ˜20 mg) into a volumetric flask (5 mL), and dissolved with dry toluene. ε-caprolactone was then added to the solution (5 mmol, 0.554 mL), mixed thoroughly, and divided into individual vials. Vials were sealed with isolation tape and added simultaneously to a pre-heated oil bath set to 80° C. Vials were removed at set time intervals and immediately submerged in an ice bath. The solution was then exposed to air and a portion of the crude mixture was dissolved in wet CDCl.sub.3 to determine conversion via NMR. Pentane/Hexane was added to the remaining aliquot to precipitate the resulting polymer followed by the removal of all volatiles under high vacuum. A 10 mg/mL THF solution of the polymer was then prepared for GPC analysis.
[0403] To better understand the effect coordination type has on the rate of polymerization, kinetic studies were conducted in toluene (0.9 M solution of ε-CL in toluene, 200:1 monomer:catalyst) at 80° C. All polymerizations showed expected increases in M.sub.n and narrow PDI values which implies a well-controlled, living-polymerization. Calculated and experimental M.sub.n values were in good agreement for 2 growing polymer chains per metal center throughout the duration of each experiment indicating that the two chains grow at a similar rate with similar initiation times. (
[0404] Polymerization reactions conducted in neat ε-CL show similar trends to those in toluene, however, they are hampered by an increase in viscosity with increasing conversion. As such, several reactions show experimental M.sub.n higher than calculated values at high conversion. This may be due to chain coupling at the metal centre. Additionally, PDI values remained narrow for all catalysts (1.05-1.37). Several catalysts were also tested in the melt at lower catalyst loading (1:1000, [1]:[ε-CL]) and all maintain their activity.
ω-Pentadecalactone Polymerisation
[0405] The general polymerisation conditions were as follows: In a glovebox, catalyst was weighed (˜7 mg) into a vial, along with ω-pentadecalactone and, in cases where the reaction was not run neat, enough toluene to produce a 1 M solution in lactone. The vial was sealed and the stirring solution was immersed in an oil bath preheated to 100° C. After the desired time aliquots of the crude reaction mixture were taken for analysis by .sup.1H NMR in CDCl.sub.3. Samples were then cooled to 0° C., exposed to air and quenched with wet hexanes. Volatiles were removed under vacuum and a 25 mg/mL CHCl.sub.3 solution was prepared for GPC. The conversion of ω-PDL to PPDL was determined by integration of the methylene proton peaks of the .sup.1H NMR spectra, δ 4.30-3.95.
[0406] Following the successful formation of PCL, the ROP of PDL was screened with the new family of catalysts. Polymerizations were conducted under similar conditions, in toluene solution at 100° C. (1:100 [I]:[ω-PDL], 1 M [ω-PDL]; Table 6) and in the melt (1:100 [I]:[ω-PDL] Table 6). As expected, the ROP of PDL is universally slower than CL. The order in catalyst, however, remains the same with Type C>Type B>Type A-II>Type A-I.
[0407] Molecular weights are considerably higher than anticipated for two growing chains. Advantageous water in the reaction may serve to deactivate a portion of catalyst causing an increase in M.sub.n, however PPDL produced from (L.sub.8).sub.2Ti(O.sup.iPr).sub.2 with freshly distilled PDL and unpurified PDL gave very similar conversion and M.sub.n after 5 hours. This suggests that even at high temperature (L).sub.2Ti(O.sup.iPr).sub.2 catalysts are relatively tolerant to impurities, such as water.
TABLE-US-00006 TABLE 6 Polymerisation of ω-pentadecalactone in toluene Catalyst Time Conv. M.sub.n M.sub.n Coordination Entry (mol %).sup.a (h) (%).sup.c (exp).sup.d (calc).sup.e Ð Type (L.sub.1).sub.2Ti(O.sup.iPr).sub.2 (1%) 4 2 — — — A-I (L.sub.1).sub.2Ti(O.sup.iPr).sub.2 (1%) 24 5 — — — A-I (L.sub.3).sub.2Ti(O.sup.iPr).sub.2 (1%) 4 5 — — — A-II (L.sub.3).sub.2Ti(O.sup.iPr).sub.2 (1%) 24 27 7,680 3,250 1.49 A-II (L.sub.4).sub.2Ti(O.sup.iPr).sub.2 (1%) 4 4 — — — B (L.sub.4).sub.2Ti(O.sup.iPr).sub.2 (1%) 24 53 14,890 6,370 1.74 B (L.sub.4).sub.2Ti(O.sup.iPr).sub.2 (1%) 48 72 21,710 8,650 1.79 B (L.sub.5).sub.2Ti(O.sup.iPr).sub.2 (1%) 4 7 — — — B (L.sub.5).sub.2Ti(O.sup.iPr).sub.2 (1%) 24 32 3,430 3,850 1.89 B (L.sub.6).sub.2Ti(O.sup.iPr).sub.2 (1%) 4 35 5,330 4,210 1.60 C (L.sub.6).sub.2Ti(O.sup.iPr).sub.2 (1%) 24 96 36,470 11,540 1.69 C (L.sub.7).sub.2Ti(O.sup.iPr).sub.2 (1%) 4 17 5,860 2,040 1.38 C (L.sub.7).sub.2Ti(O.sup.iPr).sub.2 (1%) 24 47 14,789 5,650 1.70 C (L.sub.8).sub.2Ti(O.sup.iPr).sub.2 (1%) 4 10 5,100 1,200 1.30 C (L.sub.8).sub.2Ti(O.sup.iPr).sub.2 (1%) 24 55 24,311 6,610 1.59 C (L.sub.8).sub.2Ti(O.sup.iPr).sub.2 (1%) 72 95 6,960 11,418 2.15 C (L.sub.1).sub.2Ti(O.sup.iPr).sub.2 (1%).sup.b 5 32 17,610 3,850 1.46 A-I (L.sub.3).sub.2Ti(O.sup.iPr).sub.2 (1%).sup.b 5 42 5,050 A-II (L.sub.4).sub.2Ti(O.sup.iPr).sub.2 (1%).sup.b 5 41 16,500 4,930 1.76 B (L.sub.7).sub.2Ti(O.sup.iPr).sub.2 (1%).sup.b 5 62 30,050 7,450 2.09 C (L.sub.8).sub.2Ti(O.sup.iPr).sub.2 (1%).sup.b 5 54 16,167 6,490 1.89 C (L.sub.8).sub.2Ti(O.sup.iPr).sub.2 (1%).sup.b* 5 48 13,880 5,770 2.34 C .sup.a1M ω-PDL in toluene, 100° C., N.sub.2 .sup.bNeat ω-PDL, 100° C., N.sub.2 *Utilizing unpurified ω-PDL .sup.c cCalculated by .sup.1H NMR of the methylene region. .sup.dMeasured by GPC relative to polystyrene standard and uncorrected .sup.eM.sub.n(calc) = (conversion/100) × loading/[2 growing chains] × RMM(ωPDL)
Part B
Example 7—Ligand Synthesis
Amine Ligands
[0408] Following the formation of imine ligands previously described (L.sub.1-8) a reduction with excess NaBH.sub.4 could be performed to yield amine ligands (L.sub.4-8′). These ligands were characterized through .sup.1H and .sup.13C{.sup.1H} NMR.
##STR00021##
Synthesis of HL.SUB.4.′
[0409] 2 equivalents of NaBH.sub.4 (0.49 g, 12.84 mmol) were slowly added to HL.sub.4 (2.00 g, 6.42 mmol) dissolved in ethanol (20 mL), and the solution was stirred for 2 hours, until it turned from yellow to colourless. Water (10 mL) was added dropwise to the flask at 0° C. causing a white precipitate to form. Concentrated HCl was added dropwise until a neutral pH was obtained. The reaction was left without stirring for an hour, then the solid was filtered, washed with cold water, and dried in a vacuum oven at 40° C. Isolated Yield: 1.91 g, 6.08 mmol, 95%. .sup.1H NMR (400 MHz, CDCl.sub.3) δ (ppm): 9.10 (s, 1H), 7.16 (s, 3H), 6.88-6.87 (d, 1H), 6.83 (t, 1H), 6.77-6.75 (d, 1H), 4.13 (s, 2H), 3.93 (s, 3H), 3.62 (bs, 1H), 3.35 (septet, 2H), 1.29-1.27 (d, 12H). .sup.13C{.sup.1H} NMR (125 MHz, CDCl.sub.3) δ (ppm): 148.0, 146.2, 143.1, 141.3, 125.4, 124.0, 123.9, 121.0, 119.5, 110.9, 56.1, 54.4, 28.1, 24.5.
[0410]
[0411]
Synthesis of HL.SUB.5.′
[0412] 4 equivalents of NaBH.sub.4 (0.50 g, 13.19 mmol) were slowly added to HL.sub.5 (1.00 g, 3.30 mmol) which was partially dissolved in ethanol (20 mL), and the reaction was stirred for 3 hours, until the solution turned colourless. Water (40 mL) was added slowly to the flask at 0° C., and was left without stirring overnight, producing a small amount of off-white aggregated solid. The liquid was decanted off and recrystallised from ethanol to give a solid which was washed with pentane and dried under vacuum. Isolated Yield: 0.71 g, 2.32 mmol, 71%..sup.1H NMR (400 MHz, CDCl.sub.3) δ (ppm): 7.47-7.43 (m, 4H), 7.39-7.34 (m, 1H), 7.24-7.20 (td, 1H), 7.13-7.11 (dd, 1H), 6.87-6.79 (m, 5H), 6.38 (s, 1H), 4.44 (bs, 1H), 4.39-4.38 (m, 2H), 3.89 (s, 3H). .sup.13C{.sup.1H} NMR (125 MHz, CDCl.sub.3) δ (ppm): 146.7, 144.9, 144.0, 139.4, 130.2, 129.4, 128.9, 128.7, 128.5, 127.3, 124.5, 120.7, 119.5, 117.7, 111.6, 109.8, 56.0, 44.1.
[0413]
[0414]
Synthesis of HL.SUB.6.′
[0415] 2 equivalents of NaBH.sub.4 (0.66 g, 17.52 mmol) were slowly added to HL.sub.6 (2.50 g, 8.76 mmol) dissolved in ethanol (30 mL), and the reaction was stirred for 2 hours, until the solution turned colourless, and a white precipitate appeared. Water (20 mL) was added dropwise to the flask at 0° C. without stirring. The solid formed was filtered, washed with cold water and dried under vacuum. Isolated Yield: 2.20 g, 7.66 mmol, 87%..sup.1H NMR (400 MHz, CDCl.sub.3) δ (ppm): 6.79-6.77 (m, 1H), 6.72 (t, 1H), 6.60-6.59 (m, 1H), 3.99 (s, 2H), 3.86 (s, 3H), 2.10 (bs, 3H), 1.72-1.60 (m, 12H). .sup.13C{.sup.1H} NMR (125 MHz, CDCl.sub.3) δ (ppm): 148.4, 147.9, 124.0, 119.9, 118.3, 110.6, 55.9, 51.3, 43.9, 42.1, 36.5, 29.4.
[0416]
[0417]
Synthesis of HL.SUB.7.′
[0418] 12 equivalents of NaBH.sub.4 (1.15 g, 37.83 mmol) were added to HL.sub.7 (1 g, 2.5 mmol) dissolved in ethanol (30 mL), over the course of 8 hours, until the solution turned colourless. The next day water (60 mL) was added to the flask at 0° C. without stirring. The solid formed was filtered, washed with cold water and dried under vacuum. Isolated Yield: 0.937 g, 2.36 mmol, 95%..sup.1H NMR (500 MHz, CDCl.sub.3) δ (ppm): 7.97 (s, 1H), 7.34 (s, 2H), 6.90 (m, 1H), 6.84 (d, 2H), 4.09 (d, 2H), 3.91 (s, 3H), 3.82 (t, 1H), 1.49 (2, 18H), 1.32 (s, 9H).
[0419]
Synthesis of HL.SUB.6.′
[0420] 12 equivalents of NaBH.sub.4 (1.15 g, 30.49 mmol) were added gradually to HL.sub.8 (1.00 g, 2.45 mmol) which was partially dissolved in ethanol (20 mL) over 4 hours, producing a colourless solution. The flask was left to stir overnight and an off-white solid formed. Water (10 mL) was added dropwise to the flask at 0° C. HCl was added to neutralise the solution and the reaction was stirred for an hour. The resulting white solid was filtered and washed with cold water twice. Because some solid appeared in the filtrate, this was re-filtered, washed similarly, and all product was dried in a vacuum oven at 40° C. Isolated Yield: 0.74 g, 1.86 mmol, 74%. .sup.1H NMR (400 MHz, CDCl.sub.3) δ (ppm): 10.63 (s, 1H), 7.50-7.23 (m, 15H), 6.83-6.80 (d, 1H), 6.72 (t, 1H), 6.53-6.51 (s, 1H), 3.93 (s, 3H), 3.59 (s, 2H), 2.56 (bs, 1H). .sup.13C{.sup.1H} NMR (125 MHz, CDCl.sub.3) δ (ppm): 148.3, 146.9, 144.8, 129.0, 128.5, 127.2, 123.9, 121.1, 119.4, 110.8, 72.0, 56.3, 47.0, 31.3.
Fluorinated Methoxy Ligands
[0421] Synthesis of HL.sub.4.sup.F
##STR00022##
[0422] 2-Hydroxy-3-(Trifluoromethoxy)benzaldehyde) (0.50 g, 2.4 mmol) was added to a round bottom flask and dissolved in ethanol (15 mL). 2,6-diisopropylaniline (0.43 g, 2.4 mmol) was added into the stirring solution and his reaction mixture was refluxed for 24 hours resulting in a bright solution. Ethanol was removed and the crude product was recrystallized from DCM. .sup.1H NMR (400 MHz, CDCl.sub.3) δ (ppm): 13.9 (s, 1H), 8.33 (s, 1H), 7.45 (d, 1H), 7.30 (d, 1H), 7.20 (s, 3H), 6.95 (t, 1H), 2.97 (m, 2H), 1.19 (d, 12H). .sup.19F{.sup.1H} NMR (376 MHz, CDCl.sub.3) δ (ppm): 58.08
[0423]
Example 8—Complex Synthesis
Using Imine Ligands
[0424] Synthesis of [(L.sub.4.sup.F).sub.2Ti(O.sup.iPr).sub.2]
[0425] HL.sub.4F (0.50 g, 1.37 mmol) and Ti(O.sup.iPr).sub.4 (0.19 g, 0.68 mmol) were dissolved separately in toluene (5 mL and 5 mL, respectively), and cooled to −30° C. in a glovebox freezer. The two solutions were then mixed and allowed to stir for 24 hours. Volatiles were removed in vacuo and hexane (10 mL) was added to the resulting orange-yellow wax. This hexane was removed under vacuum to provide the final complex as a bright orange powder. .sup.1H NMR (400 MHz, CDCl.sub.3) δ (ppm): 8.05 (s, 2H), 7.25-7.10 (m, 10H), 6.54 (t, 2H), 4.10 (m, 2H), 3.71 (bm, 4H), 1.19-0.24 (bm, 36H). .sup.19F{.sup.1H} (376 MHz, CDCl.sub.3) δ (ppm): 58.4.
[0426]
Synthesis of [(L.sub.4).sub.2Ti(OEt).sub.2]
[0427] HL.sub.4 (0.5 g, 1.61 mmol) and Ti(OEt).sub.4 (0.18 g, 0.80 mmol) were dissolved separately in toluene (10 mL and 10 mL, respectively), and cooled to −30° C. in a glovebox freezer. The two solutions were then mixed and allowed to stir for 24 hours. Volatiles were removed in vacuo and hexane (10 mL) was added to the resulting orange-yellow solid. This hexane was removed under vacuum to provide the final complex as a bright yellow powder (0.49 g, 0.65 mmol, 81%)..sup.1H NMR (400 MHz, CDCl.sub.3) δ (ppm): 8.51-8.39 (m, 2H), 7.6-7.45 (bs, 2H), 7.13-7.09 (m, 6H), 6.90 (d, 2H), 6.74 (t, 2H), 4.32 (bs, 4H), 3.94-3.89 (m, 6H), 3.15 (bs, 4H), 1.15-1.03 (m, 30H). *Broad signals as well as shouldering suggests isomerization in solution.
[0428]
[0429]
Synthesis of [(L.sub.4).sub.2Ti(NMe.sub.2).sub.2]
[0430] HL.sub.4 (2 eq.) and Ti(NMe.sub.2).sub.4 (1 eq) were dissolved separately in toluene (10 mL and 10 mL, respectively), and cooled to −30° C. in a glovebox freezer. The two solutions were then mixed and allowed to stir for 24 hours. Volatiles were removed in vacuo and hexane (10 mL) was added to the resulting red solid. Hexane was removed under vacuum to provide the final complex as a dark red powder. Crystals suitable for XRD were grown from slow evaporation of CDCl.sub.3. .sup.1H NMR was inconclusive, most likely due to fluxionality in the catalyst.
Using Amine Ligands
General Synthesis
[0431] The appropriate amine ligand and Ti(O.sup.iPr).sub.4 in a 2:1 molar ratio, were dissolved separately in toluene (20 mL and 5 mL, respectively), and cooled in a glovebox freezer to −30° C. The dissolved ligand was added slowly to the Ti(O.sup.iPr).sub.4 solution in a Schlenk flask. After stirring for 24 hours, volatiles were removed under vacuum, and the resulting solid was twice dissolved in hexane and dried under vacuum to yield a coloured solid.
Synthesis of [(L.sub.4).sub.2Ti(O.sup.iPr).sub.2]
[0432] HL.sub.4′ (1.00 g, 3.19 mmol) was reacted with Ti(O.sup.iPr).sub.4 (0.45 g, 1.60 mmol) to give a yellow powder. Isolated Yield: 0.98 g, 1.20 mmol, 75%..sup.1H NMR (400 MHz, CDCl.sub.3) δ (ppm): 7.35-7.26 (m, 6H), 7.20-7.18 (m, 2H), 6.89-6.88 (m, 4H), 5.00 (septet, 2H), 4.26-4.24 (d, 4H), 4.04 (s, 6H), 3.91-3.87 (t, 2H), 3.75 (septet, 4H), 1.50-1.44 (m, 36H). .sup.13C{.sup.1H} NMR (125 MHz, CDCl.sub.3) δ (ppm): 152.3, 149.4, 143.9, 143.3, 126.0, 124.1, 123.9, 123.4, 117.8, 109.1, 80.2, 57.1, 51.6, 27.9, 26.0, 24.8.
[0433]
[0434]
Synthesis of [(L.sub.5).sub.2Ti(O.sup.iPr).sub.2]
[0435] HL.sub.5′ (0.40 g, 1.31 mmol) was reacted with Ti(O.sup.iPr).sub.4 (0.19 g, 1.31 mmol) to give a pale-yellow powder. Isolated Yield: 0.23 g, 0.30 mmol, 46%. .sup.1H NMR (400 MHz, CDCl.sub.3): 7.52-7.45 (m, 8H), 7.36 (m, 2H), 7.23 (m, 2H), 7.14-7.13 (dd, 2H), 6.96-6.95 (dd, 2H), 6.83 (d, 2H), 6.79 (td, 2H), 6.68-6.63 (m, 4H), 4.78 (septet, 2H), 4.50 (t, 2H), 4.38 (d, 4H), 3.7 (s, 6H), 1.23 (d, 12H). .sup.13C{.sup.1H} NMR (125 MHz, CDCl.sub.3) δ (ppm): 151.8, 148.8, 145.3, 139.8, 130.3, 129.4, 128.9, 128.7, 127.5, 127.1, 124.7, 122.2, 117.3, 116.8, 110.8, 108.5, 80.0, 56.8, 43.1, 25.5.
[0436]
[0437]
Synthesis of [(L.sub.6).sub.2Ti(O.sup.iPr).sub.2]
[0438] HL.sub.6′ (2.00 g, 6.96 mmol) was reacted with Ti(O.sup.iPr).sub.4 (0.99 g, 6.96 mmol) to give an orange solid. Isolated Yield: 1.60 g, 2.16 mmol, 62%. .sup.1H NMR (400 MHz, CDCl.sub.3): 6.90 (d, 2H), 6.65-6.60 (m, 4H), 4.84 (septet, 2H), 3.83 (s, 6H), 3.77 (d, 4H), 2.10 (s, 6H), 1.78-1.66 (m, 30H), 1.26 (d, 12H). .sup.13C{.sup.1H} NMR (125 MHz, CDCl.sub.3) δ (ppm): 152.1, 149.0, 127.1, 123.5, 117.5, 108.5, 79.8, 57.0, 50.8, 43.0, 41.3, 37.1, 29.9, 25.9.
[0439]
[0440]
Synthesis of [(L.sub.7).sub.2Ti(O.sup.iPr).sub.2]
[0441] HL.sub.7′ (0.80 g, 2.02 mmol) was reacted with Ti(O.sup.iPr).sub.4 (0.29 g, 1.01 mmol) to give a yellow solid. Isolated Yield: 0.749 g, 0.780 mmol, 77%. .sup.1H NMR (400 MHz, CDCl.sub.3): 7.40 (s, 4H), 7.14 (d, 2H), 6.74 (m, 4H), 4.71 (m, 2H), 4.08 (m, 6H), 3.90 (s, 6H), 1.58 (s, 36H), 1.39 (s, 18H), 1.20 (d, 12H).
[0442]
Example 9—Crystallographic Studies
[0443] The structure of the complexes prepared from amine ligands could in some cases be confirmed by X-ray crystallography and are shown to adopt Type C coordination (O,O/O,O coordination, Scheme 3).
[0444] Having regard to
[0445] The initiating group on the titanium could be changed from isopropoxide to ethoxide or dimethylamide by changing the titanium precursor to Ti(OEt).sub.4 or Ti(NMe.sub.2).sub.4, thus yielding (L.sub.4).sub.2Ti(OEt).sub.2 and (L.sub.4).sub.2Ti(NMe.sub.2).sub.2 respectively. The structures of these compounds were confirmed using x-ray crystallography.
Example 10—Polymerisation Studies
ROP of ε-Caprolactone, ε-Decalactone, ω-Pentadecalactone, and Rac-Lactide
[0446] Catalysts prepared from phenoxy-amine ligands were tested for the ROP of ε-caprolactone, and in the case of (L.sub.5′).sub.2Ti(O.sup.iPO.sub.2, ε-decalactone, ω-pentadecalactone, and rac-lactide. The general conditions used in each ROP polymerisation experiment are outlined below:
ε-caprolactone ROP polymerisation: In a glovebox, the catalyst was weighed (˜7 mg) into a vial, dissolved in ε-caprolactone and, in cases where solvent was used, sufficient toluene was added to form a 1 M solution in lactone. The vial was sealed and the stirring solution was immersed in an oil bath preheated to 80° C. After the desired time, samples were cooled to 0° C., exposed to air and aliquots of the crude reaction mixture were evaporated to dryness. The crude PCL was characterized as a 10 mg/mL THF solution for GPC and in CHCl3 for .sup.1H NMR spectroscopy.
ω-pentadecalactone ROP polymerisation: In a glovebox, the catalyst was weighed (˜7 mg) into a vial, along with ω-pentadecalactone and, in cases where solvent was used, sufficient toluene was added to form a 1 M solution in lactone. The vial was sealed and the stirring solution was immersed in an oil bath preheated to 100° C. After the desired time aliquots of the crude reaction mixture were taken for analysis by .sup.1H NMR in CDCl.sub.3. Samples were then cooled to 0° C., exposed to air and quenched with wet hexanes. Volatiles were removed under vacuum and a 25 mg/mL CHCl.sub.3 solution was prepared for GPC. The conversion of PDL to PPDL was determined by integration of the methylene proton peaks of the .sup.1H NMR spectra, δ 4.30-3.95.
ε-decalactone ROP polymerisation: The catalyst (0.012 g, 0.015 mmol) was dissolved in a 1 M solution of toluene (1.5 mL) and monomer (1.500 mmol: 0.255 g ε-DL), to yield a 100:1 monomer:catalyst ratio. The reaction solution was divided up into 4 separate vials, which were sealed, removed from the glovebox, and placed in a pre-heated aluminum block to stir at 100° C. At each time point, the vials were aliquoted and quenched as in the ε-CL polymerisations.
rac-lactide ROP polymerisation: LA (0.058 g, 4.0×10.sup.−4 mmol) was added to each of 4 vials along with dry toluene to give a 1M solution. The catalyst was then added to each vial, to give a 200:1 monomer:catalyst ratio. After sealing, the vials were removed from the glovebox and placed in a pre-heated aluminum block to stir at 100° C. Aliquots were taken and reactions were quenched as in the e-caprolactone polymerisations.
Reaction Kinetics
[0447] The kinetics of the ROP of ε-caprolactone using catalysts prepared from phenoxy-amine ligands were studied (
[0448] In a glovebox, catalyst was weighed (0.025 mmol, ˜20 mg) into a volumetric flask (5 mL), and dissolved with dry toluene. ε-Caprolactone was then added to the solution (0.55 mL, 5 mmol), mixed thoroughly, and divided into individual vials. Vials were sealed with isolation tape and added simultaneously to a pre-heated oil bath set to 80° C. Vials were removed at set time intervals and immediately submerged in an ice bath. The solution was then exposed to air and a portion of the crude mixture was dissolved in wet CDCl.sub.3 to determine conversion via NMR. Pentane/Hexane was added to the remaining aliquot to precipitate the resulting polymer followed by the removal of all volatiles under high vacuum. A 10 mg/mL THF solution of the polymer was then prepared for GPC analysis.
Copolymerisation Studies
[0449] Copolymerization of ε-caprolactone and rac-lactide was also achieved using (L.sub.5′).sub.2Ti(O.sup.iPr).sub.2 through subsequent addition of one monomer after full conversion of the first to yield poly(PLA-b-CL) or poly(CL-b-LA) depending on the order of addition. The general conditions used for this experiment are outlined below:
Into one vial LA (0.216 g, 1.500 mmol), toluene (1.5 mL) and the catalyst (0.012 g, 0.015 mmol) were added, giving a 100:1 monomer:catalyst ratio. This was taped, removed from the glovebox, and placed on a pre-heated aluminium block stir at 100° C. After 4 hours, the vial was taken into the glove box, an aliquot of the reaction mixture was added to C.sub.6D.sub.6, and ε-CL (0.270 g, 2.37 mmol) was added. The vial was retaped, removed from the glovebox and placed on a pre-heated aluminium block to stir for a further 3 hours at 80° C., after which the vial was opened, another aliquot was taken in C.sub.6D.sub.6, and the reaction was quenched as in previous polymerisations.
Into a second vial ε-CL (0.171 g, 1.500 mmol), toluene (1.5 mL) and the catalyst (0.012 g, 0.015 mmol) were added (100:1 monomer:catalyst ratio). This was taped, removed from the glovebox, and placed on a pre-heated metal adaptor to stir at 80° C. After 3 hours, the vial was taken into the glove box, an aliquot of the reaction mixture was added to C.sub.6D.sub.6, and LA (0.216 g, 1.500 mmol) was added. The vial was retaped, removed from the glovebox and placed on a pre-heated aluminium block to stir for a further 4 hours at 100° C., after which the vial was opened, another aliquot was taken in C.sub.6D.sub.6, and the reaction was quenched as in previous polymerisations.
.sup.1H{.sup.1H} NMR spectra for the block polymers were taken in CDCl.sub.3 after the aliquots in C.sub.6D.sub.6 were evaporated and re-dissolved. These samples were then dried under a stream of nitrogen gas and dissolved in THF for GPC analysis.
The polymers were purified by adding a solution of polymer in a small amount of DCM dropwise into stirring methanol (100 mL) to precipitate the polymer. The solid was then filtered and washed with pentane to be used for .sup.13C{.sup.1H} NMR spectra and GPC analysis of the final product.
[0450] Additionally, a one pot copolymerization of ε-caprolactone and ω-pentadecalactone with (L.sub.6).sub.2Ti(O.sup.iPr).sub.2 yielded a statistical copolymer of poly(CL-co-PDL). The general conditions used for this experiment are outlined below:
[0451] In a glovebox, catalyst (˜7 mg, 0.010 mmol) was weighed into a vial, along with w-pentadecalactone, ε-caprolactone and enough toluene to produce a 1 M solution. The vial was then sealed and the stirring solution was immersed in an oil bath preheated to 100° C. Aliquots were removed at 2.5 h and 24 h for analysis by .sup.1H NMR in CDCl.sub.3. Samples were then cooled to 0° C., exposed to air and quenched with wet hexanes.
[0452] While specific embodiments of the invention have been described herein for the purpose of reference and illustration, various modifications will be apparent to a person skilled in the art without departing from the scope of the invention as defined by the appended claims.
REFERENCES
[0453] 1. Letizia Focarete, M.; Scandola, M.; Kumar, A.; Gross, R. A., Physical characterization of poly(ω-pentadecalactone) synthesized by lipase-catalyzed ring-opening polymerization. Journal of Polymer Science Part B: Polymer Physics 2001, 39 (15), 1721-1729. [0454] 2. Nomura, R.; Ueno, A.; Endo, T., Anionic ring-opening polymerization of macrocyclic esters. Macromolecules 1994, 27, 620-621. [0455] 3. Bouyahyi, M.; Duchateau, R., Metal-Based Catalysts for Controlled Ring-Opening Polymerization of Macrolactones: High Molecular Weight and Well-Defined Copolymer Architectures. Macromolecules 2014, 47, 517-524. [0456] 4. Pepels, M. P. F.; Bouyahyi, M.; Heise, A.; Duchateau, R., Kinetic Investigation on the Catalytic Ring-Opening (Co)Polymerization of (Macro)Lactones Using Aluminum Salen Catalysts. Macromolecules 2013, 46 (11), 4324-4334. [0457] 5. van der Meulen, I.; Gubbels, E.; Huijser, S.; Sablong, R.; Koning, C. E.; Heise, A.; Duchateau, R., Catalytic Ring-Opening Polymerization of Renewable Macrolactones to High Molecular Weight Polyethylene-like Polymers. Macromolecules 2011, 44 (11), 4301-4305. [0458] 6. Sheldrick, G. M., A short history of SHELX. Acta Crystallographica Section A: Foundations of Crystallography 2008, 64, 112-122. [0459] 7. Farrugia, L. J., WinGX and ORTEP for Windows: an update. Journal of Applied Crystallography 2012, 45, 849-854. [0460] 8. Wilson, A. J. C., International Tables for Crystallography. 1st ed.; Kluwer Academic Publishers: Dordrecht, 1992; Vol. C.