ELECTRONIC STATES OF ORGANIC-MOLECULES .6. ANALYSIS OF INFRARED INTENSITIES - HYBRID ORBITAL RE-HYBRIDIZATION MODEL - CHARGE-DISTRIBUTION IN MOLECULES

A general model for analysis of infrared intensities is proposed and applied to a series of organic molecules. This model, called the hybrid orbital rehybridization model (HORM), splits the infrared intensity into a static term due to geometric reorientation of the bond moments and a dynamic term arising from bond rehybridization. A linear dependence between CH bond moments and % s character is observed, explicit formulas are proposed for the rehybridization components. Criteria for determining which vibrational modes are purely geometric are developed, then used in conjunction with ab initio calculations to obtain values of the CH and CC bond dipoles for series of compounds. Charge distributions in these molecules are also deduced from these results. © 1978, American Chemical Society. All rights reserved.