The nature of the chemical bond in di- and polynuclear metal cluster complexes as depicted by the analysis of the electron localization function

Abstract

Abstract The bonding in transition metal complexes is usually rationalized based on molecular orbital schemes. Topological approaches such as the atoms in molecules (AIM) theory or the electron localization function (ELF) analysis provides an alternative interpretation of the bonding relying on a local description. These topological theories give a very convenient framework to achieve the partition of the molecular space in regions with chemical meaning such as atoms, bonds and lone pairs. In this work we review the possibility offered by ELF to investigate the bond in di- tri- and tetranuclear metal complexes containing metal–metal bond. In the case of bimetallic complexes with different nominal bond orders of formula M2(formamidinate)4, the metal–metal interaction is associated to a large electron fluctuation between the two metallic cores and interpreted in terms of simple resonance arguments. Such fluctuation between metals can not be invoked for the trinuclear Fe3(CO)12 or the incomplete cuboidal [Mo3S4(PH3)6Cl3]4+ complexes. The metal–metal interaction in these clusters is mostly characterized by multicenter bonding as is the case for the tetranuclear heterodimetallic cubane-type complexes resulting from the insertion of Cu or Ni into the previous Mo3S4 complex. To cite this article: J. Andres et al., C. R. Chimie 8 (2005).