Thallium(III) complexes of the metalloligands [Pt2(μ-S)2(PPh3)4] and [Pt2(μ-Se)2(PPh3)4]

Reactions of [Pt2(μ-S)2(PPh3)4] with the diarylthallium(III) bromides Ar2TlBr [Ar = Ph and p-ClC6H4] in methanol gave good yields of the thallium(III) adducts [Pt2(μ-S)2(PPh3)4TlAr2]+, isolated as their BPh4- salts. The corresponding selenide complex [Pt2(μ-Se)2(PPh3)4TlPh2]BPh4 was similarly synthesised from [Pt2(μ-Se)2(PPh3)4], Ph2TlBr and NaBPh4. The reaction of [Pt2(μ-S)2(PPh3)4] with PhTlBr2 gave [Pt2(μ-S)2(PPh3)4TlBrPh]+, while reaction with TlBr3 gave the dibromothallium(III) adduct [Pt2(μ-S)2(PPh3)4TlBr2]+[TlBr4]−. The latter complex is a rare example of a thallium(III) dihalide complex stabilised solely by sulfur donor ligands. X-ray crystal structure determinations on the complexes [Pt2(μ-S)2(PPh3)4TlPh2]BPh4, [Pt2(μ-S)2(PPh3)4TlBrPh]BPh4 and [Pt2(μ-S)2(PPh3)4TlBr2][TlBr4] reveal a greater interaction between the thallium(III) centre and the two sulfide ligands on stepwise replacement of Ph by Br, as indicated by shorter Tl–S and Pt⋯Tl distances, and an increasing S–Tl–S bond angle. Investigations of the ESI MS fragmentation behaviour of the thallium(III) complexes are reported.

Reactions of [Pt2(μ-S)2(PPh3)4] with the organothallium(III) halide compounds Ar2TlBr (Ar = Ph and p-ClC6H4) and PhTlBr2 gave organothallium(III) adducts [Pt2(μ-S)2(PPh3)4TlAr2]+ and [Pt2(μ-S)2(PPh3)4TlBrPh]+; the corresponding selenide complex [Pt2(μ-Se)2(PPh3)4TlPh2]+ was also synthesised. Reaction of [Pt2(μ-S)2(PPh3)4] with TlBr3 gave [Pt2(μ-S)2(PPh3)4TlBr2][TlBr4], a rare example of a sulfide-ligated (non-organo) thallium(III) complex. X-ray structure determinations indicate increased Tl–S interactions in the series of compounds [Pt2(μ-S)2(PPh3)4TlPh2]BPh4 < [Pt2(μ-S)2(PPh3)4TlBrPh]BPh4 < [Pt2(μ-S)2(PPh3)4TlBr2][TlBr4].Figure optionsDownload as PowerPoint slide