Do spin state changes matter in organometallic chemistry?: A computational study

被引:146
作者
Carreón-Macedo, JL
Harvey, JN
机构
[1] Univ Bristol, Sch Chem, Bristol BS8 1TS, Avon, England
[2] Univ Bristol, Ctr Computat Chem, Bristol BS8 1TS, Avon, England
基金
英国工程与自然科学研究理事会;
关键词
D O I
10.1021/ja049346q
中图分类号
O6 [化学];
学科分类号
0703 ;
摘要
Spin changes occur often in organometallic chemistry, and their effect on kinetics is not well understood. We report computations on the singlet and triplet potential energy surfaces of several processes of this type and show that the topology of the individual surfaces, as well as of the crossing regions between them, can be used to rationalize the observed reactivity in all cases. In particular, the slow addition of dihydrogen to W[N(CH2CH2NSiMe3)(3)]H (Schrock, R. R.; Shih, K. Y.; Dobbs, D. A.; Davis, W. M. J. Am. Chem. Soc. 1995, 117, 6609) is shown to be a "spin-blocked" reaction with a high barrier due to the crossing between reactant triplet and product singlet surfaces. In contrast, addition of CO to TpCo(CO) (Detrich, J. L.; Reinaud, O. M.; Rheingold, A. L.; Theopold, K. H. J. Am. Chem. Soc. 1995, 117,11745) is fast because the triplet and singlet surfaces cross at low energy. Particular care is taken to use DFT methods which are in adequate agreement with experimental and high-level computational energetics for these systems.
引用
收藏
页码:5789 / 5797
页数:9
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