Structural and bonding properties of gas-phase M4C6 (M = Cu, Ag, and Au) clusters and their anions.

The structural and bonding properties of gas-phase M4C6 (M = Cu, Ag, and Au) clusters and their anions have been investigated by quantum chemical calculations. Theoretical results indicate that the lowest-energy isomers of Cu4C6−/0 clusters possess ring-like configurations. The binding motifs in the most stable isomers of Ag4C6−/0 and Au4C6−/0 clusters adopt similar linear cumulenic chain-shaped configurations. The chemical bonding analysis indicates that the M4C6−/0 (M = Cu, Ag, and Au) complexes have σ plus π double delocalized bonding characters and the C atoms exhibit strong covalent bonding interactions, especially for Ag4C6−/0 and Au4C6−/0 clusters. The molecular orbital analysis shows that M4C6 neutrals have shell-closed electronic structures with large HOMO−LUMO gaps, indicating that their high stability and chemical inertness. [ABSTRACT FROM AUTHOR]