Mono and dinuclear bis(ortho-tolyl)platinum(II) compounds containing diethyl sulfide ligands: Synthesis, DFT studies and use as precursors in cycloplatination reactions

Abstract

The synthesis of bis(ortho-tolyl)platinum(II) compounds containing diethyl sulfide ligands from [PtCl2(SEt2)2] and ortho-tolyl-lithium is presented. Formation of a dimer [Pt(4-MeC6H4)2(μ-SEt2)]2 is evidenced by 1H NMR and HR-MS-ESI(+) spectra and the monomer trans-anti-[Pt(2-MeC6H4)2(SEt2)2] is characterized by X-ray diffraction analyses. Theoretical studies indicate that dimerization of the most stable form of the monomer (cis-syn) to the most stable conformer of the dinuclear species (αββα) is favored (ΔE = −10.1 kJ/mol). The reactions of the dimer [Pt(4-MeC6H4)2(μ-SEt2)] with imine ligands 4-ClC6H4CH = NCH2CH2NMe2 and 2-Br,6-FC6H3CH = NCH2Ph gave a tridentate [C, N, N'] five-membered and a bidentate [C, N] seven-membered platinacycles, respectively.