A bonding-reactivity relationship for (carbon dioxide)bis(tricyclohexylphosphine)nickel: a comparative solid-state-solution nuclear magnetic resonance study (phosphorus-31, carbon-13) as a diagnostic tool to determine the mode of bonding of carbon dioxide to a metal center

31P and 13C NMR spectra in the solid state and in solution,at variable temperature, have been used for the first time to determine a direct correlation of the modes of bonding of CO2 in Ni(PCy3)2(CO2) in the two states. In solution, at 173 K, CO2 is η2-CO bonded to Ni and 31P and 13C chemical shifts are almost identical with the value found for the solid complex, while a dynamic process averages, in solution,the two P atoms (ΔG≠ = 39.3 kJ mol-1) at room temperature through an intramolecular motion. The modification of the mode of bonding of CO2 to a metal center that occurs when a solid sample is dissolved in a solvent may be relevant to the reactivity of CO2-transition metal complexes, as shown by the reaction of coordinated CO2 with electrophiles (H+, Ag+) and H2. The temp. can play a role.