Planar hexacoordinate gallium

Abstract

We report the first planar hexacoordinate gallium (phGa) center in the global minimum of the GaBe6Au6+ cluster which has a star-like D6h geometry with 1A1g electronic state, possessing a central gallium atom encompassed by a Be6 hexagon and each Be-Be edge is further capped by an Au atom. The electronic delocalization resulting in double aromaticity (both σ and π) provides electronic stability in the planar form of the GaBe6Au6+ cluster. The high kinetic stability of the title cluster is also understood by Born-Oppenheimer molecular dynamics simulations. The energy decomposition analysis in combination with the 'natural orbitals for chemical valence' theory reveals that the bonding in the GaBe6Au6+ cluster is best expressed as the doublet Ga atom with 4s24p⊥1 electronic configuration forming an electron-sharing π bond with the doublet Be6Au6+ moiety followed by Ga(s)→[Be6Au6+] σ-backdonation and two sets of Ga(p‖)←[Be6Au6+] σ-donations. This journal is