CPt(IV) activation in new trimethylplatinum(IV) complexes: nucleophilic attack at metalcarbon bond

Reaction of the tetranuclear complex [Me3PtI]4 with the ligand o-Ph2P(E)C6H4SMe (E=S, Se) in a 1:4 molar ratio yields the mononuclear neutral complexes [Me3PtI{η2-MeSC6H4P(E)Ph2-S,S}] (E=S(1), Se(2)). Iodide abstraction from these compounds with AgPF6 in the presence of a ligand L (PPh3, py) leads to cationic complexes of the type [Me3Pt(η2-MeSC6H4P(E)Ph2-E,S)L]PF6 [E=S, L=PPh3 (3), Py (4); E=Se, L=Py (5)]. However, using complex 2 and the ligand PPh3 under identical conditions induces a reductive elimination reaction affording the Pt(II) complex [MePt(η2-MeSC6H4PPh2-P,S)(PPh3)]PF6 (6). Reactions of complexes 3 and 4 with NaI reveal a nucleophilic attack of the iodide to one of the methyl groups bonded to the platinum center generating a series of subsequent side reactions. Complex [Me3Pt{η2-MeSC6H4P(S)Ph2-S,S}(py)]PF6·CH2Cl2 (4) was additionally characterised by X-ray diffraction. The platinum atom exhibits a distorted octahedral coordination, bonded to three methyl carbon atoms in a facial arrangement; a bidentate chelate S,S′-bonded ligand and a nitrogen atom of the pyridine ligand complete the metal coordination sphere.