Dicyanoaurate-based heterobimetallic uranyl coordination polymers.

The first series of uranyl ([UO2 ]2+ )-dicyanoaurate coordination polymers and molecular complexes has been synthesized. Reactions of [A][Au(CN)2 ] (A = [n Bu4 N]+ or [(Ph3 P)2 N]+ ([PPN])) and uranyl nitrate in alcoholic solvents in ambient light led to [A]2 [(UO2 )2 (μ-η2 :η2 -O2 )(NO3 )2 (μ-Au(CN)2 )2 ], 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][UO2 (NO3 )2 Au(CN)2 ], from acetone, and a molecular analogue, [PPN]2 [UO2 (NO3 )2 (Au(CN)2 )2 ], from acetonitrile, none of which exhibited aurophilic interactions. The addition of 2,2'-bipyridine to the initial reaction resulted in [UO2 (bipy)(MeO)(MeOH)]2 [(μ-Au(CN)2 )(Au(CN)2 )], 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 [UO2 (Me2 bipy)Au(CN)2 ]2 [(μ-OH)2 ], generated through aurophilic bonds and hydroxide ligands. The incorporation of 2,2':6',2''-terpyridine (terpy) using solvothermal conditions resulted in [[UO2 (terpy)]2 (μ-NO3 )(μ-O)][Au(CN)2 ], a molecular salt with no aurophilic interactions. Emission spectra attributable to aurophilic interactions are observed in [n Bu4 N]2 [(UO2 )2 (μ-η2 :η2 -O2 )(NO3 )2 (μ-Au(CN)2 )2 ], while all others only show emission typical of the uranyl cation.