No abstract

Reaction of HAuCl4 x 3 H2O with excess HSAr (Ar = C6F5 or C6F4H) in ethanol, followed by addition of [Et4N]Cl, produced [Et4N][Au(SAr)4] (Ar = C6F5 (1a) or C6F4H (1b)) as red crystalline solids in high yield. These complexes are rare examples of homoleptic gold(III) thiolate complexes. The crystal structures 1 show square planar geometry at the gold center with elongated Au-S bonds. Both complexes undergo reversible reductive elimination/oxidative addition processes in solution via thermal and photochemical pathways. Equilibrium constant and photostationary state measurements indicate that the relative importance of the two pathways depends on the nature of the aromatic groups. The metal-containing reductive elimination products, [Et4N][Au(SAr)2] (Ar = C6F5 (2a) or C6F4H (2b)), were confirmed by both independent synthesis and crystallographic characterization. Cross-reactions between either 1 or 2 and various disulfides led to ligand exchange via an addition-elimination process, a previously unknown reaction pathway for ligand exchange at gold(I) centers.

Gold thiolate polymers ([ArSAu]n) were prepared via two synthetic routes - the direct reaction of an aromatic thiolate (ArSH) with HAuCl4, or the reaction of an isonitrilegold(I) chloride complex with a thiolate anion. The former route, which is general to almost all thiols, yields an amorphous and non-luminescent material. The latter route, which is more limited in scope, proceeds via an isonitrilegold( I) thiolate complex and typically yields a crystalline and luminescent material. Addition of electron-donating groups to the thiol aromatic ring leads to more rapid polymer formation and loss of luminescence while addition of electron-withdrawing groups slows or stops polymer formation and leads to a red-shift of the luminescence of the final polymeric materials. Two isonitrilegold(I) thiolate complexes with varying numbers of fluorine substituents on the thiolate aromatic ring were characterized crystallographically - C8H17NCAu(p-FC6H4S) and C12H25NCAu(2,4-F2C6H3S). As the fluorination of the aromatic ring increases, no significant changes were observed in the bond lengths of the complexes; however, the intermolecular Au-S distances lengthen while the aurophilic interaction distances decrease. These results suggest clear relationships between the molecular structure and both the supramolecular structure and photophysical properties in these materials