Effects of anions on the solid state structures of linear gold(I) complexes of the type (o-xylyl isocyanide)gold(I) (monoanion)

The preparation, spectroscopic, and structural characterization of four gold(I) complexes, (o-xylylNC)AuX with X as I, Br, Cl or CN, are reported. Each crystallizes in a unique, solvent-free form with varying aurophilic interactions between the linear, two-coordinate molecules. Thus, (o-xylylNC)AuCl forms a simple dimer, while the bromo and iodo analogs form slightly kinked chains with extended Au Au Au units. The bromo complex differs from the iodo complex due to the fact that an independent, non-interacting (o-xylylNC)AuBr unit lies off to the side of the linear chain. The structure of (o-xylylNC)AuCN consists of a complex grid which involves kinked chains of gold atoms cross linked by another aurophilically connected triad of gold centers. The complexes are all luminescent at room temperature in solution and in the solid state.