Infrared and Raman spectra of (η⁶‐mesitylene)M(CO)₃ complexes (MCr, Mo or W): An insight into metal–arene bonding

Abstract

Abstract Infrared and Raman spectra of mesitylene complexes of chromium, molybdenum and tungsten tricarbonyls have been studied. Bands have been assigned and intesities calculated for a number of important modes. The intensities are related to the polarities and polarizabilities of individual bonds within the molecules. Variations of bond properties with change of metal M in the (η 6 ‐mesitylene)M(CO) 3 complexes have been examined. The results are interpreted in terms of the relative importance of π‐donation from the arene to the metal and of δ‐backbonding. A molecular orbital scheme is proposed which accounts for the changes observed in the degree of π‐and δ‐bonding within the group of complexes studied.