Infrared intensities: a comprehensive quantitative analysis for transition metal carbonyls M(CO)₆ (M=Cr, Mo,and W) and Ni(CO)₄

Abstract

A comprehensive analysis of infrared intensities has been made for Cr(CO)₆, Mo(CO)₆, W(CO)₆, and Ni(CO)₄ molecules. Making use of the isotopic frequencies reported by Jones, McDowell, and Goldblatt, a matrices have been evaluated. The atomic polar tensors and dipole moment derivatives δμ_g/δS_j for all possible sign combinations have been reported. The correct sign combination has been determined from the criterion of maximum ξ² value as reported earlier. The bond moment parameters and atomic charges have been determined using the modified first order approach. The atomic charges obtained for Cr, Mo, W, and Ni, respectively, are 0.55, 0.64, 0.65, and 0.11e. The atomic polar tensors are found to show systematic trends in the molecules considered and indicate that they may be predicted qualitatively for other similar molecules. The analysis of bond moment parameters and polar tensors have led to the support of general ideas about the nature of bonding between metal and CO ligands.