Unusual Si鈥揌 Bond Activation and Formation of Cationic Scandium Amide Complexes from a Mono(amidinate)-Ligated Scandium Bis(silylamide) Complex and Their Performance in Isoprene Polymerization
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- 作者：Fei Chen ; Shimin Fan ; Yibin Wang ; Jue Chen ; Yunjie Luo
- 刊名：Organometallics
- 出版年：2012
- 出版时间：May 14, 2012
- 年：2012
- 卷：31
- 期：9
- 页码：3730-3735
- 全文大小：431K
- 年卷期：v.31,no.9(May 14, 2012)
- ISSN：1520-6041
文摘
Amine elimination of scandium tris(silylamide) complex Sc[N(SiHMe2)2]3(THF) with 1 equiv of the amidine [PhC(N-2,6-iPr2C6H3)2]H in toluene afforded the neutral mono(amidinate) scandium bis(silylamide) complex [PhC(N-2,6-iPr2C6H3)2]Sc[N(SiHMe2)2]2 (1) in 93% isolated yield. When 1 was activated with 1 equiv of [Ph3C][B(C6F5)4] in the presence of THF, the unexpected cationic amidinate scandium amide complex [{PhC(N-2,6-iPr2C6H3)2}ScN{SiHMe2}{SiMe2N(SiHMe2)2}(THF)2][B(C6F5)4] (2) was generated. Treatment of 1 with excess AlMe3 gave the Sc/Al heterometallic methyl complex [PhC(N-2,6-iPr2C6H3)2]Sc[(渭-Me)2AlMe2]2 (3). All these complexes were well-characterized by elemental analysis, NMR spectroscopy, and X-ray crystallography. The combination 1/[Ph3C][B(C6F5)4] in toluene showed activity toward isoprene polymerization. Addition of excess AlMe3 to the 1/[Ph3C][B(C6F5)4] catalyst system switched the regioselectivity of isoprene polymerization from 3,4-specific to cis-1,4-selective.