Variable-temperature diffraction study of the barrier to rotation and zero-point motion in bis(η6-benzene) chromium

The mean squared displacements of the eta(6)-benzene ring in Cr(C6D6)(2) have been determined at. 10 temperatures; extrapolation of these displacements gives a zero-point energy of 0.89 kJ mol(-1). The individual barriers to rotation corresponding to these displacements have been determined and decrease with increasing temperature in accord with expansion of the material. (C) 2000 Elsevier Science B.V. All rights reserved.