Carbon dioxide cleavage by a Ni2 complex supported by a binucleating bis(N-heterocyclic carbene) framework

A binucleating bis(N-heterocyclic carbene) ligand was designed as a means to coordinate and proximally constrain two transition metal centers. Using an imidazopyridine-based NHC afforded a framework structurally related to previously reported para-terphenyl diphosphines. Bimetallic copper, cobalt, and nickel complexes supported by this framework were synthesized and structurally characterized. Strong interactions between the metal centers and the central arene were observed in all nickel complexes. Dinickel(0) complexes of this ligand framework were found to react with CO2 to form a dicarbonyl-bridged dinickel(0) product, demonstrating facile CO2 reduction. (C) 2014 Elsevier Ltd. All rights reserved.