THE ELECTRONIC STRUCTURE OF COORDINATED OLEFIN, MU-ALKYLIDENE, AND CARBONYL LIGANDS AS PROVIDED BY PHOTOELECTRON SPECTROSCOPY.

Abstract

This dissertation describes a study of the electronic structure of some selected cyclopentadienyl metal olefin, (mu)-alkylidene, and carbonyl complexes. While most studies of this type are largely theoretical in nature, this work relies on the experimental observations which result from the application of photoelectron spectroscopy to the measurements of the important molecular energies of these compounds. The first part of the discussion is a study of metal-olefin bonding in the CpM(CO)₂L (L = C₂H₄, C₃H₆) compounds. Of particular interest are the observed changes in ionization energies of the olefin (pi) orbital upon coordination. These results also allow a comparison of the coordination of CO and C₂H₄. The valence ionizations of μ-CH₂-[(C₅H₄CH₃)Mn(CO)₂]₂ are also presented. This example of the increasingly important μ-alkylidene complexes provides evidence of a 3C-6e configuration with a net Mn-Mn single bond. The final chapter describes a study of the valence electronic structure of the CpM(CO)₂ (M = Co, Rh; Cp = η⁵-C₅H₅⁻) and η⁵-C₅(CH₃)₅⁻ ) system. This group of four closely related molecules demonstrates how photoelectron spectroscopy can be used to monitor the electronic effects of specific chemical modifications. The intent throughout is to not only present a detailed analysis of the specific compounds chosen for this study, but to also further demonstrate the applicability of photoelectron spectroscopy to a broad spectrum of problems concerning the structural and electronic make-up of organometallic molecules.