Dicyanoaurate-based heterobimetallic uranyl coordination polymers.

The first series of uranyl ([UO])-dicyanoaurate coordination polymers and molecular complexes has been synthesized. Reactions of [A][Au(CN)] (A = [BuN] or [(PhP)N] ([PPN])) and uranyl nitrate in alcoholic solvents in ambient light led to [A][(UO)(μ-η:η-O)(NO)(μ-Au(CN))], which incorporates peroxo ligands into a one-dimensional ladder topology with alternating aurophilic and peroxo rungs. Conducting the reaction with non-alcoholic solvents formed two polymorphs of a one-dimensional chain, [PPN][UO(NO)Au(CN)], from acetone, and a molecular analogue, [PPN][UO(NO)(Au(CN))], from acetonitrile, none of which exhibited aurophilic interactions. The addition of 2,2'-bipyridine to the initial reaction resulted in [UO(bipy)(MeO)(MeOH)][(μ-Au(CN))(Au(CN))], a one-dimensional structure which propagates via a series of linear aurophilic bonds with pendant uranyl complexes; methanol and methoxy ligands provide additional connections through hydrogen bonding. The addition of 5,5'-dimethyl-2,2'-bipyridine using solvothermal conditions resulted in the one-dimensional ladder [UO(Mebipy)Au(CN)][(μ-OH)], generated through aurophilic bonds and hydroxide ligands. The incorporation of 2,2':6',2''-terpyridine (terpy) using solvothermal conditions resulted in [[UO(terpy)](μ-NO)(μ-O)][Au(CN)], a molecular salt with no aurophilic interactions. Emission spectra attributable to aurophilic interactions are observed in [BuN][(UO)(μ-η:η-O)(NO)(μ-Au(CN))], while all others only show emission typical of the uranyl cation.