Roos Björn O, Lindh Roland, Cho Han-Gook, Andrews Lester
Department of Theoretical Chemistry, Chemical Center, University of Lund, P.O.B. 124, S-221 00 Lund, Sweden, and Department of Chemistry, University of Virginia, P.O. Box 400319, Charlottesville, Virginia 22904-4319.
J Phys Chem A. 2007 Jul 19;111(28):6420-4. doi: 10.1021/jp071914b. Epub 2007 Jun 20.
Multiconfigurational quantum chemical methods (complete active space self-consistent field (CASSCF)/second-order perturbation theory (CASPT2)) have been used to study the agostic interaction between the metal atom and H(C) in the methylidene metal dihydride complexes H2MCH2, where M is a second row transition metal or the actinide atoms Th or U. The geometry of some of these complexes is highly irregular due to the formation of a three center bond CH...M, where the electrons in the CH bond are delocalized onto empty or half empty orbitals of d- or f-type on the metal. No agostic interaction is expected when M=Y, where only a single bond with methylene can be formed, or when M=Ru, because of the lack of empty electron accepting metal valence orbitals. The largest agostic interaction is found in the Zr and U complexes.
多组态量子化学方法（完全活性空间自洽场（CASSCF）/二阶微扰理论（CASPT2））已被用于研究亚甲基金属二氢化物配合物H₂MCH₂中金属原子与H（C）之间的闭壳层相互作用，其中M为第二周期过渡金属或锕系原子钍（Th）或铀（U）。由于形成了三中心键CH...M，这些配合物中的一些几何结构非常不规则，其中CH键中的电子离域到金属上d型或f型的空轨道或半满轨道上。当M = Y时，预计不会有闭壳层相互作用，因为此时只能与亚甲基形成单键；当M = Ru时，由于缺乏可接受电子的空金属价轨道，也不会有闭壳层相互作用。在Zr和U的配合物中发现了最大的闭壳层相互作用。
