Molecular Motion in Tetraphenyltin Studied by NMR

Abstract

NMR second moment and spin-lattice relaxation times in the laboratory (60 and 25 MHz) and in therotating frame (B1 = 2.1 mT) were studied for polycrystalline tetraphenyltin Sn(C6H5)4 in a wide temperaturerange. Two kinds of motions were detected: isotropic rotation of whole molecules and reorientations/oscillations of phenyl rings. A dependence of the potential energy of the molecule in the crystalon the angle of the phenyl ring rotation about the Sn-C bond was obtained on the basis of atom-atomcalculations. The amplitude of the ring-oscillations at 133 K was estimated as ± 7°. Below room temperaturethe magnetisation recovery is significantly non-exponential, which may be interpreted as dueto the correlated motion of phenyl rings.