Photoelectron Spectroscopy of High-Temperature Vapors. II. Chemical Bonding in the Group III Monohalides

Abstract

The He(I) photoelectron spectra of InCl, InBr, and InI are presented. A general description of bonding in all Group III monohalides is given on the basis of these new data, earlier data on thallium monohalides, ab initio calculations on BF, AlCl, and GaCl, and semiempirical calculations on all of the Group III monohalides. It is found that a molecular orbital localized on the electronegative atom in an ionic diatomic molecule is appropriately classified as ``bonding''; whereas a molecular orbital localized on the positive ion has an ``antibonding'' character. This classification is qualitatively different from that used to discuss covalently bound molecules.