Phys. Chem. Chem. Phys. 12, 5101-5108 (2010)

DOI: 10.1039/b924322d

On the electronic structure and stability of icosahedral r-X2Z10H12 and Z12H122- clusters; r = {ortho, meta, para}, X = {C, Si}, Z = {B, Al}

We report on the electronic structure of the 12-vertexicosahedralclustersr-X2Z10H12and Z12H122–, where X = {C,Si} and Z = {B,Al}. The least stablecluster—with the lowest HOMO–LUMO gap (Eg)—corresponds to theortho-X2Z10H12isomers for all values of X = {C,Si} and Z = {B,Al}. The well-known energetic orderE(para)<E(meta)<E(ortho)forr-carboranes is also valid for all compounds exceptr-C2Al10H12. Substitution of two atoms ofcarbonorsiliconinto theicosahedralcage B12H122−enhances considerably the stability of the system as analyzed fromEggaps, as opposite to Al12H122−, where similar gaps are found upon doublecarbonorsiliconsubstitution regardless of the positions in the cage. In order to highlight similarities and differences in the titleclusters, topological analysis of the electron density was performed, together with analysis of the deviation from polyhedronicosahedralform with (i) volumes, skewness and kurtosis calculations; and (ii) continuous shape measures.