Electronic Structure of Gold Carbonyl Compounds RAuL (R = CF3, BO, Br, Cl, CH3, HCC, Mes3P, SIDipp; L = CO, N2, BO) and Origins of Aurophilic Interactions in the Clusters [RAuL]n (n = 2–4): A Theoretical Study

The bonding nature of CF3AuCO and its clusters [CF3AuCO]n (n = 2–4) (Angew. Chem., Int. Ed. 2011, 50, 6571) have been theoretically investigated with density functional theory (B3LYP, B3LYP-D3, M06-2X, M06-2X-D3, M05-2X, M06L, B3PW91), the Hartree–Fock method (HF), second-order Møller–Plesset perturbation theory (MP2), and the coupled cluster method with perturbative triplets (CCSD­(T)) using a series of basis sets. For comparison, larger complexes that have been studied experimentally, [Mes3PAuCO]+ and [SIDippAuCO]+, were also computed. Various ligands as well as their gold clusters [RAuL]2–4 (R = OB, Br, Cl, CH3, HCC; L = CO, N2, OB) were also investigated. The Au–CO bonds consist of electrostatic attraction, Au←CO donation, and Au→CO π-back-bonding components. The LMOEDA results show that the major contributors of RAuL are found to be electrostatic, which linearly correlates with the interaction energy. Electrostatic stabilization is mainly responsible for aurophilic interactions in the formation of CF3AuCO clusters.