A novel structural rearrangement reaction of dialkylated derivatives of [Pt 2(μ-S) 2(PPh 3) 4] involving Pt-C bond formation

Abstract

Reaction of [Pt 2(μ-S) 2(PPh 3) 4] with the dialkylating agents ClCH 2C(O)CH 2Cl or ClCH 2C(NNHC(O)NH 2)CH 2Cl gives the dicationic di-μ-thiolate complexes [Pt 2{μ-SCH 2C(O)CH 2S)(PPh 3) 4] 2+ or [Pt 2{μ-SCH 2C(NNHC(O)NH 2)CH 2S} (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 2C(O)CH 2S)(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 2C(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 1J(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 2C(NNHAr)CHS} (PPh 3) 3Cl] [Ar = C 6H 3(NO 2) 2] in which a PPh 3 ligand is substituted by a chloride. © 2012 The Royal Society of Chemistry.