Platinum(II) thiosalicylate and related complexes as ligands towards mercury(II) halides; X-ray crystal structure of the tetrametallic complex {[Pt(SC6H4CO2)(PPh3)2] · HgI2}2

Article abstract of DOI:10.1016/S0277-5387(97)00342-2

The platinum(II) thiosalicylate complex [Pt(SC₆H₄CO₂)(PPh₃)₂] 1a reacts with HgI₂ to form a tetrametallic complex comprising an IHg(μ-I)₂HgI central core with the thiolate sulphur of 1a coordinated to each mercury centre, completing a distorted tetrahedral coordination environment. Overall, the structural features of the complex, determined by an X-ray diffraction study, are similar to the parent thiosalicylate complex 1a, but with an increased fold angle (59° compared to 46°) of the thiosalicylate ligand relative to the platinum coordination plane. Reactions of related five-membered ring thiolate complexes [Pt(SCHRCO₂)(PPh₃)₂] (R=H or Me) and of 1a with a range of metal cations were investigated using ³¹P NMR spectroscopy. Changes in the ¹J(PtP) coupling constants are discussed in terms of coordination to the various metal halide moieties. Reactions of the organomercury(II) thiosalicylate complex Thiomersal (EtHgSC₆H₄CO₂Na) with cis-[PtCl₂(PPh₃)₂], or cis-[MCl₂(dppe)] (M=Ni or Pd) leads to complete transfer of the thiosalicylate ligand from the mercury, and isolation of the previously reported thiosalicylate complexes [Pt(SC₆H₄CO₂)(PPh₃)₂] and [M(SC₆H₄CO₂) (dppe)] (M=Ni, Pd) in high yields.