Planar Elongated B 12 Structure in M 3 B 12 Clusters (M = Cu-Au).

Here, it is shown that the M 3 B 12 (M = Cu-Au) clusters' global minima consist of an elongated planar B 12 fragment connected by an in-plane linear M 3 fragment. This result is striking since this B 12 planar structure is not favored in the bare cluster, nor when one or two metals are added. The minimum energy structures were revealed by screening the potential energy surface using genetic algorithms and density functional theory calculations. Chemical bonding analysis shows that the strong electrostatic interactions with the metal compensate for the high energy spent in the M 3 and B 12 fragment distortion. Furthermore, metals participate in the delocalized π-bonds, which infers an aromatic character to these species.