Unambiguous hydrogenation of CO2 by coinage-metal hydride anions: an intuitive idea based on in silico experiments

Abstract

Gas phase hydrogenation of CO₂ to HCO₂⁻ by coinage-metal hydride anions, MH⁻ (M = Cu, Ag and Au), has been studied with the help of high level computational methodologies. We demonstrate that these hydride anions perform excellently in the specific hydrogenation of CO₂ to HCO₂⁻. More precisely, AgH⁻ is shown to be very active for this particular purpose. We show that CO₂ activation through the M–H⋯CO₂ pathway passes through a very low energy barrier and produces HCO₂⁻; even the metal centered activation (H–M⋯CO₂) also leads to the same product through an energy barrier less than 15 kcal mol⁻¹. A closer inspection demonstrates that electronegativity, size of the metal and hydricity of the MH⁻ species control the overall hydrogenation process.