INFRARED INTENSITIES OF CARBONYL STRETCHING MODES AND ELECTRONIC SPECTRA OF SUBSTITUTED MOLYBDENUM CARBONYLS

Intensity and frequency data for the CO stretching motion in substituted metal carbonyls are presented for compounds of the types Mo(CO)5L, trans-Mo(CO)4L2, and cis-Mo(CO)3L3. The coupling between the two A1 modes in the monosubstituted complexes has been found not to depend significantly on whether the M-C stretching force constant and various associated interaction constants are included in the vibrational analysis. The L matrix elements are used to calculate θ, the angle between axial and radial CO groups, assuming equal MCO group dipole moment derivatives for the two A1 modes. Dipole moment derivatives have been calculated assuming characteristic moments for the A1 and E modes. The electronic spectra for these complexes in the ultraviolet and visible regions are reported. The infrared and electronic spectral results indicate that substitution of CO by a ligand capable of π bonding does not necessarily result in any increase in π bonding to the remaining CO groups. © 1968, American Chemical Society. All rights reserved.