Bifunctional Lewis Acids. Synthesis and Olefin Polymerization Chemistry of the 1,1-Di[bis(perfluorophenyl)boryl]alkenes RCH=C[B(C6F5)2]2 (R = t-Bu, C
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- 作者：Katrin Kö ; hler ; Warren E. Piers ; Adam P. Jarvis ; S. Xin ; Y. Feng ; A. M. Bravakis ; Scott Collins ; William Clegg ; Glenn P. A. Yap ; and Todd B. Marder
- 刊名：Organometallics
- 出版年：1998
- 出版时间：August 3, 1998
- 年：1998
- 卷：17
- 期：16
- 页码：3557 - 3566
- 全文大小：165K
- 年卷期：v.17,no.16(August 3, 1998)
- ISSN：1520-6041
文摘
The synthesis and characterization, including crystallographic analysis, of the bifunctionalboranes RCH=C[B(C6F5)2]2 (R = t-C4H9, 1a; C6H5, 1b; C6F5, 1c) by regioselective hydroboration of the corresponding 1-boraalkynes using HB(C6F5)2 are reported herein. Compounds1a and 1b have been screened as cocatalysts for ethylene polymerization in the presence ofCp2ZrMe2 (3) under a variety of conditions. NMR spectroscopic studies indicate that Cp2Zr[
2-ButC
CB(C6F5)2] (4a), Cp2ZrMe(C6F5), the organoborane Me2BC6F5, and methane gasare the final products formed from reaction of 1a with 3 in toluene solution at roomtemperature. The stoichiometric mechanism for this transformation has been elucidatedthrough variable-temperature NMR studies. Complex 4a and MeB(C6F5)2 (7) were preparedindependently and screened as ethylene polymerization catalysts and cocatalysts, respectively. Compound 4a is inactive for ethylene polymerization, either alone or in the presenceof additional 1a. However, the combination of Cp2ZrMe2 and 7 gives rise to the species[Cp2ZrMe]+[Me2B(C6F5)2]- (8), which although unstable at room temperature in solution(decomposing over a period of 60 min to give Cp2ZrMe(C6F5) and the organoborane Me2BC6F5), is active for ethylene polymerization. From a comparison of activity and MW data,it is concluded that the putative ion pairs formed from 1a (or 1b) and 3 lack sufficient thermalstability at conventional polymerization temperatures and that the polymerization activityobserved can be interpreted as arising from species 8.
2-ButCCB(C6F5)2] (4a), Cp2ZrMe(C6F5), the organoborane Me2BC6F5, and methane gasare the final products formed from reaction of 1a with 3 in toluene solution at roomtemperature. The stoichiometric mechanism for this transformation has been elucidatedthrough variable-temperature NMR studies. Complex 4a and MeB(C6F5)2 (7) were preparedindependently and screened as ethylene polymerization catalysts and cocatalysts, respectively. Compound 4a is inactive for ethylene polymerization, either alone or in the presenceof additional 1a. However, the combination of Cp2ZrMe2 and 7 gives rise to the species[Cp2ZrMe]+[Me2B(C6F5)2]- (8), which although unstable at room temperature in solution(decomposing over a period of 60 min to give Cp2ZrMe(C6F5) and the organoborane Me2BC6F5), is active for ethylene polymerization. From a comparison of activity and MW data,it is concluded that the putative ion pairs formed from 1a (or 1b) and 3 lack sufficient thermalstability at conventional polymerization temperatures and that the polymerization activityobserved can be interpreted as arising from species 8.