Computational evidence of the importance of substituent bulk on agostic interactions in Ir(H)2(PtBu2Ph)2+

被引:107
作者
Ujaque, G
Cooper, AC
Maseras, F [1 ]
Eisenstein, O
Caulton, IG
机构
[1] Indiana Univ, Dept Chem, Bloomington, IN 47405 USA
[2] Univ Montpellier 2, LSDSMS UMR 5636, F-34095 Montpellier 5, France
关键词
D O I
10.1021/ja9729894
中图分类号
O6 [化学];
学科分类号
0703 ;
摘要
While Ir(H)(2)((PBu2Ph)-Bu-t)(2)(+) has been shown experimentally to have two agostic Bu-t groups, ab initio B3LYP calculations on IrH2[P(Et)H-2](2)(+) show that the CH3 group of the phosphine ligand does not form any agostic bond with the strongly electron-deficient (14-valence electron) metal. In contrast, integrated molecular mechanics/molecular orbital (IMOMM) calculations on the full complex Ir(H)(2)((PBu2Ph)-Bu-t)(2)(+) duplicate the experimentally observed agostic interaction. Thus, at least in this case, the agostic interaction is due in part to the trapping of a C-H bond in the vicinity of the metal by the steric effects of the other groups of the bulky phosphine. This necessity of steric "constraint" identifies an additional influential factor for the agostic interaction.
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页码:361 / 365
页数:5
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