Noble Gas Binding Ability of Metal-Bipyridine Monocationic Complexes (Metal=Cu, Ag, Au): A Computational Study

Noble gas (Ng) binding ability of monocationic M-bipyridine (M=Cu, Ag, Au) complexes is investigated at the MPW1B95/cc-pVTZ/cc-pVTZ-PP level. While the bond dissociation energy, enthalpy change, and free energy change for the dissociation process are computed to assess the efficacy of the Ng binding ability of these complexes, topological analysis of electron density, natural bond orbital, and energy decomposition analyses are carried out to characterize the nature of Ng=M bonds. The range of Ng-M dissociation energy values is within 5.8-13.7 kcal/mol for Cu, 4.0-12.0 kcal/mol for Ag, and 5.5-19.7 kcal/mol for Au complexes with gradual increase in moving from Ar to Rn. For a given Ng, the Ng binding ability is highest for Au followed by Cu and Ag complexes, except for the Ar case. In all the cases, the Kr-Rn dissociation processes from the respective bound complexes are endergonic in nature at room temperature. The interaction between Ng and M centers are supported dominantly by orbital and ionic interactions with almost equal contribution. The partial covalent nature of Ng-M bonds is also reflected in the topological analysis of electron density.