The preparation, properties and X-ray structures of gold(I) trithiophosphite complexes

The first gold(I) trithiophosphite complexes were synthesised and fully characterised. Reaction of (tht)AuX (X = Cl, C6F5; tht = tetrahydrothiophene) with trithiophosphites (RS)3P (R = Me, Ph) and the bicyclic [(SCH2CH2S)PSCH2]2 (2L) afforded the corresponding molecular complexes (RS)3PAuX [R = Me, X = Cl (1); R = Me, X = C6F5 (2); R = Ph, X = Cl (3); R = Ph, X = C6F5 (4)], and 2L(AuX)2 [X = Cl (5), X = C6F5 (6)]. Reacting (tht)AuCl consecutively with two mole equivalents of (MeS)3P and then AgOTf, gave the ionic compound {[(MeS)3P]2Au}OTf (7). The compounds were characterised by multinuclear NMR spectroscopy, IR measurements and mass spectrometry, and the crystal and molecular structures of 1, 3, 6, two polymorphs of 2 as well as the known (MeO)3PAuCl (8) were determined by X-ray diffraction. The halide complexes 1 and 8 are isostructural and exhibit infinite chains of “crossed-sword”-type aurophilic interactions with Au⋯Au contact distances of 3.2942(3) and 3.1635(4) Å, respectively. Complex 6 exhibits a long Au⋯Au contact of 3.4671(9) Å. Au⋯S interactions between 3.3455(7) and 3.520(2) Å are present in the structures of 1 and one polymorph of 2.