Platinum(II) Mixed Ligand Complexes with Thiourea Derivatives, Dimethyl Sulphoxide and Chloride: Syntheses, Molecular Structures, and ESCA Data

The platinum(II) mixed ligand complexes [PtCl(L1‐6)(dmso)] with six differently substituted thiourea derivatives HL, R2NC(S)NHC(O)R′ (R = Et, R′ = p‐O2N‐Ph: HL1; R = Ph, R′ = p‐O2N‐Ph: HL2; R = R′ = Ph: HL3; R = Et, R′ = o‐Cl‐Ph: HL4; R2N = EtOC(O)N(CH2CH2)2N, R′ = Ph: HL5) and Et2NC(S)N=CNH‐1‐Naph (HL6), as well as the bis(benzoylthioureato‐κO, κS)‐platinum(II) complexes [Pt(L1, 2)2] have been synthesized and characterized by elemental analysis, IR, FAB(+)‐MS, 1H‐NMR, 13C‐NMR, as well as X‐ray structure analysis ([PtCl(L1)(dmso)] and [PtCl(L3, 4)(dmso)]) and ESCA ([PtCl(L1, 2)(dmso)] and [Pt(L1, 2)2]). The mixed ligand complexes [PtCl(L)(dmso)] have a nearly square‐planar coordination at the platinum atoms. After deprotonation, the thiourea derivatives coordinate bidentately via O and S, DMSO bonds monodentately to the PtII atom via S atom in a cis arrangement with respect to the thiocarbonyl sulphur atom. The Pt—S‐bonds to the DMSO are significant shorter than those to the thiocarbonyl‐S atom. In comparison with the unsubstituted case, electron withdrawing substituents at the phenyl group of the benzoyl moiety of the thioureate (p‐NO2, o‐Cl) cause a significant elongation of the Pt—S(dmso)‐bond trans arranged to the benzoyl‐O—Pt‐bond. The ESCA data confirm the found coordination and bonding conditions. The Pt 4f7/2 electron binding energies of the complexes [PtCl(L1, 2)(dmso)] are higher than those of the bis(benzoylthioureato)‐complexes [Pt(L1, 2)2]. This may indicate a withdrawal of electron density from platinum(II) caused by the DMSO ligands.