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

Abstract

Reaction of the tetranuclear complex [Me 3PtI] 4 with the ligand o-Ph 2P(E)C 6H 4SMe (E=S, Se) in a 1:4 molar ratio yields the mononuclear neutral complexes [Me 3PtI{η 2-MeSC 6H 4P(E)Ph 2-S,S}] (E=S( 1), Se( 2)). Iodide abstraction from these compounds with AgPF 6 in the presence of a ligand L (PPh 3, py) leads to cationic complexes of the type [Me 3Pt(η 2-MeSC 6H 4P(E)Ph 2-E,S)L]PF 6 [E=S, L=PPh 3 ( 3), Py ( 4); E=Se, L=Py ( 5)]. However, using complex 2 and the ligand PPh 3 under identical conditions induces a reductive elimination reaction affording the Pt(II) complex [MePt(η 2-MeSC 6H 4PPh 2-P,S)(PPh 3)]PF 6 ( 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 [Me 3Pt{η 2-MeSC 6H 4P(S)Ph 2-S,S}(py)]PF 6·CH 2Cl 2 ( 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.