Elucidating the Mechanism of Simultaneous Activation of CH4 and CO2 Mediated by Single Group 10 Metal Anions in Gas Phase.

Theoretical calculations predict that, besides the reported single metal anion Pt-, Ni- can also mediate the co-conversion of CO2 and CH4 to form [CH3-M(CO2)-H]- complex, followed with transformation to C-C coupling product [H3CCOO-M-H]- (A), hydrogenation products [H3C-M-OCOH]- (B) and [H3C-M-COOH]-. For Pd-, a fourth product channel leading to PdCO2-…CH4 becomes more competitive. For Ni-, the feed order must be CO2 first, as the weaker donor-acceptor interaction between Ni- and CH4 raises a high C-H activation barrier, which is reduced by [Ni-CO2]-. For Ni-/Pt-, the highly exothermic products A and B are similarly stable with submerged barrier that favors B. The smaller barrier difference between A and B for Ni- suggests the C-C coupling product is more competitive for Ni- than Pt-.  The charge redistribution from M- is the driving force for product B channel. This study adds our understanding of single atomic anions to activate CH4 and CO2 simultaneously.