Experimental Comparison of the Bonding in Inorganometallic and Organometallic Complexes by Photoelectron Spectroscopy

Abstract

The broad strides that have been made in recent years in the synthesis and structural characterization of organometallic and inorganometallic complexes have led to increasing interest in understanding the electronic structure and bonding in these molecules. The principles and models of bonding that have developed for organometallic complexes, as typified by the Dewar—Chatt— Duncanson model of synergistic metal—ligand bonding, have also provided the foundation for understanding the chemical and physical properties of inorganometallic complexes. These principles go beyond the basic crystal field or valence bond descriptions of d-orbital splitting diagrams of classical coordination compounds. The models now consider the precise electron-donor, electron-acceptor, and bond-forming capabilities of the ligands. For every interaction of an organic ligand with a metal there is a symmetry-equivalent interaction of an inorganic ligand with a metal. This has been termed the “isolobal analogy.”^(1,2) The differences lie in the precise spatial distribution and energy of the valence electrons of the ligands. Experimental approaches are essential to obtain a quantitative comparison of the electron distribution and bonding of organic and inorganic ligands with transition metals.