Electronic structures of electron-rich octahedrally condensed transition-metal chalcogenide clusters

The electronic structures of some electron-rich octahedrally condensed transition-metal chalcogenide clusters are analyzed with the aid of extended Hückel and density functional molecular orbital calculations. A simple orbital approach is developed to analyze the electron counts of these clusters, which do not obey any existing electron-counting rules. Different electron counts are allowed, depending upon the nature of the metal. Optimal counts are discussed. Metal-metal bonding is generally weak in these species. Consequently, their structural arrangements are mainly governed by metal-ligand interactions.