9.31 - Theoretical Treatment of Ligated Clusters Containing Transition Metals

Abstract

This chapter deals with the electronic structure of isolable ligand-protected molecular clusters containing transition-metal elements. The relationships existing between the structure and the number of valence electrons of various types of clusters are discussed in the framework of the major electron-counting rules used in inorganic chemistry, such as those originating from the polyhedral electron pair theory or the superatom model. The theoretical basis of these general theories is recalled and illustrated with various examples of compounds. Their limits of application are then explored and a collection of selected clusters, which do not satisfy the classical electron-counting schemes, serves this purpose. The contribution of quantum chemical calculations on various types of clusters to the development of electron-counting rule as well as to the understanding of their exceptions is discussed. Recent work on nano-sized species is included and some trends for future theoretical treatments of ligated transition-metal clusters are suggested.