CONFORMATIONAL EQUILIBRIA IN THE SOLID-STATE - CONFORMATIONAL EQUILIBRIUM IN BICYCLO[3.3.1]NONANE DERIVATIVES STUDIED BY SOLID-STATE SPECTROSCOPY

Several derivatives of bicyclo [3.3.1] nonan-9-one were examined by CP/MAS NMR spectroscopy in the solid state. Contrary to an earlier report based on X-ray crystallography, no conclusive evidence was found for the existence of a chair/chair-chair/boat equilibrium in the temperature range - 100 to + 20-degrees-C. It is concluded that if such solid-state equilibria exist they have free energies of activation for ring inversion in the solid of less than 31 kJ mol-1.