Synthesis, Structure, and Properties of the First Disulfur and Diselenium Complexes of Platinum

The first platinum disulfur and diselenium complexes, [Pt(S2)(ArMe2P)2] (Ar = Tbt (4a), Bbt (4b)) and [Pt(Se2)(ArMe2P)2] (Ar = Tbt (5a), Bbt (5b)), have been synthesized by the reactions of the corresponding overcrowded platinum(0) complexes [Pt(ArMe2P)2] with elemental sulfur and selenium. Molecular structures of 4b and 5b were established by X-ray crystallographic analyses, which show a novel three-membered PtE2 (E = S, Se) ring structure with a square planar geometry around the platinum center. The oxidation of 4b and 5b with an equimolar amount of m-chloroperbenzoic acid or tert-butyl hydroperoxide in dichloromethane afforded the corresponding disulfur and diselenium monoxide complexes [Pt(E2O)(BbtMe2P)2] (E = S (6), Se (7)), respectively. An interesting difference in reactivity between 6 and 7 was shown in the further reactions with an excess of oxidants, which produced the corresponding O,S-coordinated thiosulfate complex [Pt(S2O3) (BbtMe2P)2] (8) and the O,O-coordinated selenite complex [Pt(SeO3)(BbtMe2P)2] (11), respectively. The dynamic behavior in solution was revealed by the variable-temperature NMR spectroscopy for 4b, 5b, 8, and 11, which indicates the existence of the intramolecular CH···E (E = O, S, Se) interactions between the methine hydrogens of the o-bis(trimethylsilyl)methyl groups and the Pt-bonded heteroatoms.