SYNTHESES OF THE CYCLIC PLATINUM(II) THIOLATE COMPLEXES [PT(SCH2C(O)CH2)(PPH3)2] AND [(PT[SCH2C(O)CH2](PPH3))2]

Treatment of [Pt(eta2-RCH=CHR)(PPh3)2] (R = H or Ph) with 1,3-dichloro acetone gave the chloroacetonyl complex cis-[PtCl{CH2C(O)CH2Cl}(PPh3)2 ] 1 which readily cyclised in high yield to the thiolate complex [Pt{S CH2C(O)CH2}(PPh3)2] 2 by treatment with sodium sulfide. Complexes 1 an d 2 have been fully characterised by IR and NMR spectroscopies, and by elemental analysis. Ligand substitution reactions of complex 2 with a n excess of isocyanide RNC (R = Bu(t), Bu(n) or 2,6-xylyl), an excess of tri-n-butylphosphine or 1 equivalent of trimethyl phosphite in dich loromethane afforded the monosubstituted complexes [Pt{SCH2C(O)CH2}(PP h3)(L)]). These complexes were typically isolated as a mixture of isom ers, with the major isomer in each case having the PPh3 ligand trans t o CH2. Treatment of complex 2 with an excess of trimethyl phosphite yi elded the bis(phosphite) complex [Pt(SCH2C(O)CH2}{P(OMe)3}2]. Reaction of 2 with [Rh2(mu-Cl)2(CO)4] afforded a mixture of products from whic h the thiolate-bridged dimeric complex [{Pt[SCH2C(O)CH2](PPh3)}2] was isolated and characterised by a single-crystal X-ray diffraction study , which confirmed the formulation of these complexes as five-membered ring thiolates.