Cis configured bis phosphine platinum(II) chalcogenolate complexes: Structures, NMR and computational studies

Reactions of [PtCl2(P∩P)] (P∩P = dppm, dppe or dppp) with Pb(SMes)2 and sodium arylchalcogenolates yielded mononuclear complexes of the type, cis-[Pt(EAr)2(P∩P)] [EAr = EMes (E = S, Se or Te; Mes = mesityl), Sepym (pym = 2-pyrimidyl) or SepymMe2 (pymMe2 = 4,6-dimethyl-2-pyrimidyl]. These complexes were characterized by elemental analyses and NMR (1H, 31P) spectroscopy. The molecular structures of [Pt(SeMes)2(dppp)]·½C6H6, [Pt(TeMes)2(dppp)]·3C6H6, [Pt(SeC4H3N2)2(dppm)] and [Pt{SeC4H(4,6-Me2)N2}2(dppm)]·CH2Cl2 were established by single crystal X-ray diffraction analyses. An attempt has been made to rationalize the NMR data with the nature of chelated bis phosphine ligand, chalcogen atom and aryl substituent on the chalcogen atom. The energy difference (ΔE), calculated by DFT, is very small between various conformers. The calculated ΔE between various conformers of mesitylthiolate dppp complex lies in the range of 0.1–1.0 kcal/mol; the same for mesitylselenolate complex lies in the range of 0.5–2.2 kcal/mol and for mesityltellurolate complex it is in the range of 1.0–3.0 kcal/mol.