A conformational polymorph of Ph3PAu[SC(OEt)=NPh] featuring an intramolecular Au···π interaction

Abstract

Abstract A conformational polymorph, form β, for Ph3PAu[SC(OEt)=NPh] has been characterised. Like the original structure (form α), the molecule features a linear P–Au–S geometry. The difference between molecular structures rests with the relative disposition of the thiolate ligand which places the N-bound aryl ring in close proximity to the gold centre (form β) rather than the oxygen atom (form α). Density functional theory calculations show the molecule with the Au···π interaction is more stable by 5.2 kcal/mol than the one with the Au···O contact. The molecular packing of both forms are stabilised by C–H···O and C–H···π interactions which make approximately the same contribution to the overall Hirshfeld surfaces. However, key indicators, e.g. crystal packing efficiency and density, and the computational results suggest form β is the thermodynamically favoured form.