title: Density functional theory studies of thermal activation of methane by MH+ (M = Ru, Rh, and Pd).
abstract: The dehydrogenation reaction mechanisms of methane catalyzed by a ligated transition metal MH(+) (M = Ru, Rh, and Pd) have been investigated theoretically. Activation of methane by MH(+) complexes is proposed to proceed in a one-step manner via one transition state: MH(+) + CH(4) --> MH(+)CH(4) --> [TS] --> (MCH(3)(+))H(2) -->MCH(3)(+) + H(2). Both high-spin and low-spin potential energy surfaces are characterized in detail. Our calculations indicate that the ground-states species have low electron spin and a dominant 4d(n) configuration for RuH(+), RhH(+), and PdH(+), and the whole reaction proceeds on the ground-states potential energy surfaces with a spin-allowed manner. The MH(+) (M = Ru, Rh, and Pd) complexes are expected from the general energy profiles of the reaction pathways to efficiently convert methane to metal methyl, thus RuH(+), RhH(+), and PdH(+) are likely to be excellent mediators for the activity of methane. In the reactions of MH(+) with methane, the H(2) elimination from the dihydrogen complex is quite facile without barriers. The exothermicities of the reactions are close for Ru, Rh, and Pd: 11.1, 1.2, and 5.2 kcal/mol, respectively.
authors.affiliation: Gansu Key Laboratory of Polymer Materials, College of Chemistry and Chemical Engineering Northwest Normal University, Lanzhou 730070, People's Republic of China.
authors.forename: Wenqiang
authors.initials: W
authors.lastname: Li
authors.forename: Zhiyuan
authors.initials: Z
authors.lastname: Geng
authors.forename: Yongcheng
authors.initials: Y
authors.lastname: Wang
authors.forename: PenJi
authors.initials: P
authors.lastname: Yan
authors.forename: Xu
authors.initials: X
authors.lastname: Zhang
authors.forename: Zheng
authors.initials: Z
authors.lastname: Wang
authors.forename: Fengxia
authors.initials: F
authors.lastname: Liu