LOCAL ORBITAL AND BOND INDEX CHARACTERIZATION OF HYBRIDIZATION

Hybridization, a local property of the wave function, is discussed in terms of the molecular orbital theory. Two methods for prediction of hybridization are introduced, one based on orbital localization and the other on an extension of Wiberg's bond index. When a localized description of the wave function is possible, a situation which allows unambiguous definition of hibridization, the two methods give indistinguishable results. Calculations employing the complete neglect of differential overlap approximation for a variety of molecules, including alkanes, alkenes, ethers, alcohols, and carboxylic acids, give a reliable qualitative account of trends in hybridization. Agreement between the calculated p character Xp and estimates of Xp from nmr coupling constants is good. Correspondingly, a local orbital estimate of the hybridization can be used to predict the coupling between carbon-13 nuclei and directly bound protons in molecules for which the experimental data are not available. © 1969, American Chemical Society. All rights reserved.