Insertion of Nitriles into a Zirconium-Iridium Heterobimetallic Complex: A Mechanistic Study
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- 作者：J. Robin Fulton ; Tracy A. Hanna ; and Robert G. Bergman
- 刊名：Organometallics
- 出版年：2000
- 出版时间：February 21, 2000
- 年：2000
- 卷：19
- 期：4
- 页码：602 - 614
- 全文大小：321K
- 年卷期：v.19,no.4(February 21, 2000)
- ISSN：1520-6041
文摘
The reaction of Cp2Zr(
-N-tBu)IrCp* (1) with nitriles (RC
N) yields the cyclometalatedspecies Cp2Zr(-N-tBu)(-NC(H)(R)CH2-
5-C5Me4)Ir (R = C6H5 (2a), o-Et-C6H4 (2b), (p-CH3)C6H4 (2c), (p-CF3)C6H4 (2d), (p-MeO)C6H4 (2e), cyclopropyl (2f), CH(Me)2 (2g), NC(CH2)3(2h)). An intermediate is observed in the reaction of 1 with cyanocyclopropane. Thisintermediate has been characterized by NMR spectroscopy as a tetramethylfulvene complexwith a bridging alkylidene-amido moiety, Cp2Zr(-N-tBu)(-NCRH)(5-C5Me4CH2)Ir (R =cyclopropyl; 3). Kinetic simulations were performed and provided evidence that theintermediate is productive. The reaction of 1 with 2-arylacetonitriles yields two noninterconvertible complexes: a cyclometalated species (4), analogous to complex 2, and the newolefinic species Cp2Zr(-N-tBu)(-N-CHCH(R)IrCp* (R = C6H5 (5a), R = (p-CF3)C6H4 (5b),R = (p-MeO)C6H4 (5c)). The reaction pathways for the formation of both 4 and 5 proceedthrough the fulvene complex 3; however, the product ratio 5:4 was found to be dependentupon the reaction conditions.
-N-tBu)IrCp* (1) with nitriles (RCN) yields the cyclometalatedspecies Cp2Zr(-N-tBu)(-NC(H)(R)CH2-5-C5Me4)Ir (R = C6H5 (2a), o-Et-C6H4 (2b), (p-CH3)C6H4 (2c), (p-CF3)C6H4 (2d), (p-MeO)C6H4 (2e), cyclopropyl (2f), CH(Me)2 (2g), NC(CH2)3(2h)). An intermediate is observed in the reaction of 1 with cyanocyclopropane. Thisintermediate has been characterized by NMR spectroscopy as a tetramethylfulvene complexwith a bridging alkylidene-amido moiety, Cp2Zr(-N-tBu)(-NCRH)(5-C5Me4CH2)Ir (R =cyclopropyl; 3). Kinetic simulations were performed and provided evidence that theintermediate is productive. The reaction of 1 with 2-arylacetonitriles yields two noninterconvertible complexes: a cyclometalated species (4), analogous to complex 2, and the newolefinic species Cp2Zr(-N-tBu)(-N-CHCH(R)IrCp* (R = C6H5 (5a), R = (p-CF3)C6H4 (5b),R = (p-MeO)C6H4 (5c)). The reaction pathways for the formation of both 4 and 5 proceedthrough the fulvene complex 3; however, the product ratio 5:4 was found to be dependentupon the reaction conditions.