Group 10 metal anions Ni−/Pd−/Pt− behave differently in mediating the co-conversion of CO2/CH4 to C−C coupling and hydrogenation products.
Quantum chemistry 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 by 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 increases the 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 in the presence of 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.Zum Volltext