The structure of π-methylcyclopentadienyl manganese tricarbonyl as determined from P.M.R. studies in the nematic phase

Abstract

From the study of the P.M.R. spectrum of π-methylcyclopentadienyl manganese tricarbonyl dissolved in a nematic phase, the geometry of the proton skeleton is determined. It is found that the ring protons lie at the corners of a regular pentagon. Modes of possible rotation of the methyl group are considered and their influence on the spectrum is discussed. There is an indication that the rotation is hindered by a 3-fold potential due to the presence of Mn(CO)3 group. Three S values are needed for a complete description of the molecular orientation. Of these, one affects the spectrum only when the rotation of the methyl group is hindered.