Gold coordination by tertiary phosphane sulfides

Treatment of the ditertiary phosphane sulfides (CH2)(n)[PPh2S](2), 1a-1d, n = 1-4, with equivalent amounts of (dimethylsulfide) gold(I) chloride (Me2S)AuCl affords the dinuclear complexes 2a-2d with an AuCl unit attached to each sulfur atom. The chlorides can be converted into the bromides 3a-3e by metathesis using KBr, or by reacting 1d with (tetrahydrothiophene)gold bromide. With [(Ph3P)Au](+) O3SCF3- as the aurating agent for the diphosphane disulfides, the corresponding dicationic products are obtained: {(CH2)(n)[SPPh2AuPPh3](2)}(2+). 2 O3SCF3- (4b-4d, n = 2-4). An excess of the reagents does not lead to polygold clustering at the sulfur atoms, and P-S cleavage occurs instead to give sulfonium salts {S[Au(PPh3)](3)}(+) X-. The reaction of Ph3PS with equimolar quantities of [(Ph3P)Au]O3SCF3 leads to the cationic 1:1 complex 5, and with an excess of the agent the P-S bond is ruptured. The structures of compounds 4b and 4d were determined by single-crystal X-ray diffraction. The dications have crystallographic centers of inversion, the coordination at the gold atoms is linear [4b: 179.03(3)degrees; 4d: 175.29(2)degrees] and the angles at the sulfur atoms are acute [4b: 97.76(4)degrees; 4d: 96.37(3)degrees], but there are no short Au-Au contacts.