Rs. Armstrong et al., INFRARED AND RAMAN-SPECTRA OF (ETA-6-C6H6-NXN)CR(CO)3 COMPLEXES WHEREX=ME (N=0-6) OR OME (N=0-2) - A STUDY OF METAL-LIGAND INTERACTIONS, Journal of molecular structure, 323, 1994, pp. 15-28
A systematic study is reported of the infrared and Raman spectra of me
thyl and methoxy substituted benzene chromium tricarbonyl complexes (e
ta6-C6H6-nXn)Cr(CO)3 where X = Me (n = 0-6) or OMe (n = 0-2). Bands ha
ve been assigned and intensities calculated for a number of vibrationa
l modes. Trends in the wavenumbers and band intensities of the arene-m
etal, metal-carbonyl and carbonyl bonds are examined to gain an insigh
t into metal-ligand interactions and intramolecular electron rearrange
ments with progressive substitution on the arene. The results are disc
ussed with regard to sigma-, pi- and delta-contributions to arene-meta
l bonding and of sigma- and pi-components in metal-carbonyl and carbon
yl bonding. The intensities are related to the polarities and polariza
bilities of individual bonds within the molecules, and variations in t
hese bond electronic properties with arene substitution are examined.