A BONDING REACTIVITY RELATIONSHIP FOR NI(PCY3)2(CO2) - A COMPARATIVE SOLID-STATE SOLUTION NUCLEAR-MAGNETIC-RESONANCE STUDY (P-31, C-13) AS A DIAGNOSTIC-TOOL TO DETERMINE THE MODE OF BONDING OF CO2 TO A METAL CENTER

P-31 and C-13 nuclear magnetic resonance 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 eta2-CO bonded to nickel and P-31 and C-13 chemical shifts are almost identical with the value found for the solid complex, while a dynamic process averages, in solution, the two phosphorus atoms (DELTAG(double dagger) = 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 H-2. The temperature can play an important role.