New Structural Features of Unsupported Chains of Metal Ions in Luminescent [(NH3)4Pt][Au(CN)2]2·1.5(H2O) and Related Salts

Luminescent [(NH3)4Pt][Au(CN)2]2·1.5(H2O), which forms from aqueous solutions of [(NH3)4Pt]Cl2 and K[Au(CN)2], crystallizes with extended chains of the two ions with multiple close Pt···Au (3.2804(4) and 3.2794(4) (angstrom)) and Au···Au (3.2902(5), 3.3312(5), and 3.1902(4) (angstrom)) contacts. Nonluminescent [(NH3)4Pt][Ag(CN)2]2·1.4(H2O) is isostructural with [(NH3)4Pt][Au(CN)2]2·1.5(H2O). Treatment of [(NH3)6Ni]Cl2 with K[Au(CN)2] forms [(NH3)2Ni][Au(CN)2]2 in which the [Au(CN)2]- ions function as nitrile ligands toward nickel, which assumes a six-coordinate structure with trans NH3 ligands. The [Au(CN)2]- ions self-associate into linear columns with close Au···Au contacts of 3.0830(5) (angstrom), and pairs of gold ions in these chains make additional but longer (3.4246(5) (angstrom)) contacts with other gold ions.