A novel structural rearrangement reaction of dialkylated derivatives of [Pt2(μ-S)2(PPh3)4] involving Pt–C bond formation

Abstract

Reaction of [Pt(2)(μ-S)(2)(PPh(3))(4)] with the dialkylating agents ClCH(2)C(O)CH(2)Cl or ClCH(2)C(=NNHC(O)NH(2))CH(2)Cl gives the dicationic di-μ-thiolate complexes [Pt(2){μ-SCH(2)C(O)CH(2)S)(PPh(3))(4)](2+) or [Pt(2){μ-SCH(2)C(=NNHC(O)NH(2))CH(2)S}(PPh(3))(4)](2+), isolated as BPh(4)(-) salts and characterised by ESI mass spectrometry, NMR spectroscopy and single-crystal X-ray crystallography. Treatment of the complex [Pt(2){μ-SCH(2)C(O)CH(2)S)(PPh(3))(4)](2+), which contains a [6.6.4] bicyclic system, with hydroxide ions results in deprotonation of a CH(2) group and rearrangement of the resulting monocation, giving [Pt(2)(μ-SCH(2)C(O)CHS}(PPh(3))(4)](+), isolated as its PF(6)(-) salt. An X-ray structure determination shows the complex to have a novel rearranged [6.5.5] bicyclic system containing a Pt-S-Pt-S-C five-membered ring with a Pt-C bond. The alkyl ligand has a high trans-influence, manifest in a long trans Pt-P bond and small (1)J(PtP) coupling constant to the trans PPh(3) ligand. Reaction of [Pt(2)(μ-S)(2)(PPh(3))(4)] with the 2,4-dinitrophenylhydrazone derivative of 1,3-dichloroacetone leads to the closely related complex [Pt(2){μ-SCH(2)C(=NNHAr)CHS}(PPh(3))(3)Cl] [Ar = C(6)H(3)(NO(2))(2)] in which a PPh(3) ligand is substituted by a chloride.