Further studies on the coordination chemistry of [Pt2(μ-S)2(PPh3)4] towards indium(III) substrates

The reactivity of the metalloligand [Pt2(μ-S)2(PPh3)4] towards a variety of indium(III) substrates has been explored. Reaction with excess In(NO3)3 and halide (KBr or NaI) gave the four-coordinate adducts [Pt2(μ-S)2(PPh3)4InX2]+[InX4]− (X = Br, I). An X-ray structure determination on the iodo complex revealed a slightly distorted tetrahedral coordination geometry at indium. In contrast, reaction of [Pt2(μ-S)2(PPh3)4] with indium(III) chloride was more complex; the ion [Pt2(μ-S)2(PPh3)4InCl2]+ was initially observed in solution (using ESI mass spectrometry), and isolated as its BPh4− salt. Analysis of [Pt2(μ-S)2(PPh3)4InCl2]+[BPh4]− by ESI MS showed the parent cation when analysed in MeCN solution. However in solutions containing methanol, partial solvolysis occurred to give the di-indium species [{Pt2(μ-S)2(PPh3)4InCl(OMe)}2]2+ (proposed to contain an In2(μ-OMe)2 unit with five-coordinate indium) and its fragment ion [Pt2(μ-S)2(PPh3)4InCl(OMe)]+. Reaction of [Pt2(μ-S)2(PPh3)4] with InCl3·3H2O, 8-hydroxyquinoline (HQ) and trimethylamine in methanol gave the adduct [Pt2(μ-S)2(PPh3)4InQ2]+, isolated as its PF6− salt. The same cationic complex is formed when [Pt2(μ-S)2(PPh3)4] is reacted with InQ3 in methanol, but in this case the product is contaminated with the mononuclear complex [(Ph3P)2PtQ]+ formed by disintegration of the trinuclear complex [Pt2(μ-S)2(PPh3)4InQ2]+ with byproduct Q−. [(Ph3P)2PtQ]+BPh4− was independently prepared from cis-[PtCl2(PPh3)2] and HQ/Me3N, and is the first example of a platinum 8-hydroxyquinolinate complex containing phosphine ligands.