Structure and Bonding in CE5− (E=Al–Tl) Clusters: Planar Tetracoordinate Carbon versus Pentacoordinate Carbon. Issue 11 (3rd May 2018) - Ravell, Estefanía
Abstract: The structure, bonding, and stability of clusters with the empirical formula CE5 − (E=Al–Tl) have been analyzed by means of high‐level computations. The results indicate that, whereas aluminum and gallium clusters have C 2 v structures with a planar tetracoordinate carbon (ptC), their heavier homologues prefer three‐dimensional C 4 v forms with a pentacoordinate carbon center over the ptC one. The reason for such a preference is a delicate balance between the interaction energy of the fifth E atom with CE4 and the distortion energy. Moreover, bonding analysis shows that the ptC systems can be better described as CE4 −, with 17‐valence electrons interacting with E. The ptC core in these systems exhibits double aromatic (both σ and π) behavior, but the σ contribution is dominating. Abstract : Flat or warped? Competing planar tetracoordinate carbon (ptC) versus pentacoordinate carbon atoms in the CE5 − (E=Al, Ga, In, Tl; see figure) clusters have been unveiled in terms of distortion and interaction energies. The ptC systems predominate for the lighter atoms (Al, Ga), which are described as a CE4 − fragment with 17‐valence electrons interacting with the E atom.