Side-on Coordination in Isostructural Nitrous Oxide and Carbon Dioxide Complexes of Nickel

A nickel complex incorporating an N2O ligand with a rare eta(2)-N,N '-coordination mode was isolated and characterized by X-ray crystallography, as well as by IR and solid-state NMR spectroscopy augmented by N-15-labeling experiments. The isoelectronic nickel CO2 complex reported for comparison features a very similar solid-state structure. Computational studies revealed that eta(2)-N2O binds to nickel slightly stronger than eta(2)-CO2 in this case, and comparably to or slightly stronger than eta(2)-CO2 to transition metals in general. Comparable transition-state energies for the formation of isomeric eta(2)-N,N '- and eta(2)-N,O-complexes, and a negligible activation barrier for the decomposition of the latter likely account for the limited stability of the N2O complex.