Geometries and conformational processes in phencyclidine and a rigid adamantyl analogue: variable-temperature NMR,...

The barriers to rotation of the aryl groups of m-nitrophenyladamantylpiperidine and m-nitrophenylcyclohexylpiperidine have been studied by variable-temperature NMR spectroscopy. NMR spectra of the free bases and salts of phenyladamantylpiperidine and phenylcyclohexylpiperidine (phencyclidine) and an X-ray crystal structure of the adamantane derivative verify the preferred conformations of these molecules in solution and the solid state. Force-field calculations provide additional information on the energetics of conformational processes in these molecules.