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.

Keywords:

• Bulky phosphine ligand
• CH–chalcogen interaction
• oxidation
• platinum–diselenium complex
• platinum–disulfur complex

We thank Ms. Toshiko Hirano and Ms. Tomoko Terada of the Microanalytical Laboratory of the Institute for Chemical Research of Kyoto University for the elemental analysis and HRMS spectra. This work was partially supported by Grants-in-Aid for COE Research on Elements Science (No. 12CE2005), Scientific Research on Priority Area (A) (No. 14078213), 21st Century COE on Kyoto University Alliance for Chemistry, and “Nanotechnology Support Project? from the Ministry of Education, Culture, Sports, Science, and Technology of Japan.