title: Spin-Blocking Effect in CO and H2 Binding Reactions to Molybdenocene and Tungstenocene: A Theoretical Study on the Reaction Mechanism via the Minimum Energy Intersystem Crossing Point.
abstract: Potential energy profiles and electronic structural interpretation of the CO and H2 binding reactions to molybdenocene and tungstenocene complexes [MCp2] (M = Mo and W, Cp = cycropentadienyl) were studied using density functional theory calculations and ab initio multiconfigurational electronic structure calculations. Experimentally observed slow H2 binding was reasonably explained in terms of the spin-blocking effect. Electronic structural analysis at the minimum-energy intersystem crossing point (MEISCP) revealed that the singly occupied molecular orbital's π-bonding/σ-antibonding character in the M-CO/H2 moiety determines the energy levels of the MEISCP. Analysis of the reaction coordinate showed that the singlet-triplet gap significantly depends on the Cp-M-Cp angle. Therefore, not only the metal-ligand distance but also the Cp-M-Cp angle is an important reaction coordinate to reach the MEISCP, the transition state of H2 binding. The role of spin-orbit coupling is also discussed.
authors.affiliation: Institute for Catalysis, Hokkaido University , N21 W10 Kita-ku, Sapporo, Hokkaido 001-0021, Japan.|Department of Chemistry, Biology and Marine Science, Faculty of Science, University of the Ryukyus , 1 Senbaru, Nishihara, Okinawa 903-0213, Japan.
authors.forename: K-Jiro
authors.initials: KJ
authors.lastname: Watanabe
authors.affiliation: Institute for Catalysis, Hokkaido University , N21 W10 Kita-ku, Sapporo, Hokkaido 001-0021, Japan.
authors.forename: Naoki
authors.initials: N
authors.lastname: Nakatani
authors.affiliation: Institute for Catalysis, Hokkaido University , N21 W10 Kita-ku, Sapporo, Hokkaido 001-0021, Japan.
authors.forename: Akira
authors.initials: A
authors.lastname: Nakayama
authors.affiliation: Department of Chemistry, Biology and Marine Science, Faculty of Science, University of the Ryukyus , 1 Senbaru, Nishihara, Okinawa 903-0213, Japan.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Higashi
authors.affiliation: Institute for Catalysis, Hokkaido University , N21 W10 Kita-ku, Sapporo, Hokkaido 001-0021, Japan.
authors.forename: Jun-Ya
authors.initials: JY
authors.lastname: Hasegawa