^3- M = Cr, Mo, W: Bonding and electronic structure of cluster assemblies with metal carbonyls

Understanding the factors controlling the band gap energy of cluster-assembled materials is an important step toward nanoassemblies with tailored properties. To this end, we have investigated the band gap energies of cluster assemblies involving arsenic clusters bound to carbonyl charge-transfer complexes, M(CO)₃, M = Cr, Mo, W. The binding of a single charge-transfer complex is shown to have a small effect on the band gap energy because the arsenic lone pair orbital and metal carbonyl orbitals are closely aligned in energy, resulting in a gap similar to the original cluster. The band gap energy is also found to be insensitive to the architecture of the assembled material. In the case where two charge-transfer complexes are bound to the cluster, the bottom of the conduction band is shown to be localized on a solvent molecule bound to the metal carbonyl.