A Digallane Gold Complex with a 12-Electron Auride Center: Synthesis and Computational Studies

The reaction of Power’s digalladeltacyclane with Au­(PPh3)Cl led to formation of a digallium gold complex (2) with both chloride and gold bridging between two gallium atoms. The bonding parameters from the solid-state structure of 2 suggested a 12e– Au center stabilized by weakly coordinated aryl groups. DFT calculations at the M05-2X/[LANL2TZ­(f),6-311G­(d)] level indicated a Ga–Au–Ga banana bond with no bonding interactions between gallium atoms. The gold carries an NBO charge of −0.0956 e– and is best viewed as an auride. The weak intramolecular interactions between Au p orbitals and σC–C and σC–H bonds of the adjacent aromatic rings amount to significant stabilization of the electron-deficient gold center. The digallium complex 2 represents the first structural example of a 12 e– organometallic auride complex, demonstrating its pseudohalide/hydride nature in bonding.