title: Agostic interaction in the methylidene metal dihydride complexes H2MCH2 (M=Y, Zr, Nb, Mo, Ru, Th, or U).
abstract: 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.
authors.affiliation: 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.
authors.forename: Björn O
authors.initials: BO
authors.lastname: Roos
authors.forename: Roland
authors.initials: R
authors.lastname: Lindh
authors.forename: Han-Gook
authors.initials: HG
authors.lastname: Cho
authors.forename: Lester
authors.initials: L
authors.lastname: Andrews