On the relationship between crystallographic and spectroscopic evidence of dynamic processes in the solid state: the cases of cis- and trans-[Fe2(η-C5H5)2(CO)4]

Abstract

The reorientational motion of the C₅H₅ ligands, evidenced in solid cis-and trans-[Fe₂(η-C₅H₅)₂(CO)₄] by magic angle spinning n.m.r. spectroscopy, has been examined by means of atom–atom pairwise potential-energy calculations. The results are compared with the X-ray crystallographic indications of extensive librational motion of the ligands around their five-fold axes in both species. A thermal motion analysis has been carried out showing that the mean-square displacement parameters contain relevant information on the occurrence of dynamic processes in the solid state.