SYNTHESIS AND PROPERTIES OF THE FIRST DISULFUR AND DISELENIUM COMPLEXES OF PLATINUM

Abstract

The reactions of overcrowded platinum(0) complexes [Pt{P(Ar)Me2}2] (Ar = 2,4,6-tris[bis(trimethylsilyl)methyl]phenyl (Tbt), 2,6-bis[bis- (trimethylsilyl)methyl]-4-[tris(trimethylsilyl)methyl]phenyl (Bbt)) with elemental sulfur and selenium resulted in the formation of the first platinum disulfur and diselenium complexes, [Pt(S2){P(Ar)Me2}2] (4a (Ar = Tbt), 4b (Ar = Bbt) and [Pt(Se2){P(Ar)Me2}2] (5a (Ar = Tbt), 5b (Ar = Bbt)) respectively. The x-ray crystallographic analyses of 4b and 5b showed 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 yielded the corresponding disulfur and diselenium monoxide complexes [Pt(E2O){P(Bbt)Me2}2] (6 (E = S), 7 (E = Se)). The further reactions of 6 and 7 with an excess of oxidants gave the corresponding O,S-coordinated thiosulfato complex [Pt(S2 O3){P(Bbt)Me2}2] (8) and the O,O-coordinated selenito complex [Pt(SeO3){P(Bbt)Me2}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 chalcogen atoms.