A dinuclear silver hydride and an umpolung reaction of CO2

Abstract

A triangular [Ag₂H]⁺ core is stabilised by the N-heterocyclic carbene (NHC) ligand 1,3-bis(2,6-diisopropylphenyl)imidazolin-2-ylidene (SIDipp). The X-ray crystal structure of this complex reveals a short silver–silver distance, and ¹⁰⁹Ag NMR spectroscopy shows substantial coupling between the silver nuclei. The complex persists for hours in solution after exposure to air and moisture. When carbon dioxide is added in the form of a Lewis-basic NHC adduct, a rapid reaction results in hydride transfer to form a bis(NHC)silver(I) formate.