Formation and structure of two luminescent salts of [Au(SCSN3)2]− obtained through the [2 + 3] cyclization of carbon disulfide and azide ion

Abstract

The colorless, two-coordinate gold(I) complex, [(H₂O)₃Na][Au(SCSN₃)₂], has been synthesized through the [2 + 3] cyclic reaction of carbon disulfide and sodium azide in the presence of the labile complex (tht)AuCl. Metathesis of [(H₂O)₃Na][Au(SCSN₃)₂], with tetra(phenyl)arsonium chloride produced colorless needles of (Ph₄As)[Au(SCSN₃)₂]. The structure of [(H₂O)₃Na][Au(SCSN₃)₂] involves linear gold coordination by two exocyclic sulfur atoms of the 1,2,3,4-thiatriazole-5-thiolate anions. These two-coordinate anions self-associate to form extended, zig-zag chains that are connected by aurophilic bonding with Au⋯Au distances of 3.2653(3) Å and 3.3090(3) Å. Remarkably, the individual S–Au–S units that are connected though aurophilic interactions are eclipsed. The structure of (Ph₄As)[Au(SCSN₃)₂] also contains linear, two-coordinate gold ions with bonding to the 1,2,3,4-thiatriazole-5-thiolate anionic ligands through the exocyclic sulfur atoms. However, in this salt, the anions self-associate through Au⋯Au bonds (Au⋯Au distance of 3.2007(3) Å) to form simple dimers, which also have an eclipsed arrangement of the ligands. Electronic structure calculations strongly suggest that the staggered geometry for the [(Au(SCSN₃))₂]⁺ dimer is energetically favored relative to the eclipsed geometry. However, attractive π-stacking interactions appear to promote the observed eclipsed arrangement of the ligands.