Bonding and stereochemistry of three-coordinated transition metal compounds

Transition metal complexes with coordination number three were considered to be characteristic of the late transition elements with d(10) configurations. The synthesis and characterization of a growing number of compounds with low coordination numbers and electron configurations from d(0) to d(8) calls for a revision of our concepts regarding the bonding and stereochemistry of such compounds. This contribution presents a general survey of molecular orbital studies on the electronic structure of coordinatively unsaturated three-coordinated complexes and discusses the presently known structures both in discrete molecules and in extended arrays. (C) 1999 Elsevier Science S.A. All rights reserved.