Aurophilicity vs. thiophilicity: directing the crystalline supramolecular arrangement in luminescent gold compounds

Abstract

Herein, we study the influence of the fluorination of thiolate ligand backbones over the solid state crystalline supramolecular arrangement in a series of seven new dinuclear fluorophenylthiolate gold(I) coordination compounds. These compounds include the bridge ligand 1,2-bis(diphenylphosphine)ethane (dppe) and have the general formula [Au₂(SR_F)₂(μ-dppe)] with SR_F = SC₆F₅ (1); SC₆HF₄-4 (2); SC₆H₃F₂-3,5 (3); SC₆H₃F₂-2,4 (4); SC₆H₄(CF₃)-2 (5); SC₆H₄F-3 (6) and SC₆H₄(CF₃)-4 (7). By the analysis of X-ray crystalline structures, we found that the increase in the fluorination degree of the ligands reduces the incidence of aurophilic interactions and collaterally favours the formation of a secondary Au⋯S (thiophilic) interaction resulting in a rhomboidal planar (AuS)₂ unit. This latter synthon recurrently competes with the expected Au–Au contacts. All the analysed compounds show visible photoluminescence in the solid state, indicating an aggregation-induced emissive behaviour, i.e. both the aurophilic and thiophilic interactions promote the emission of light by this family of gold complexes.