New Pt(II) complexes containing hemilabile thioether-pyrazole ligands. Structural analysis by 1H, 13C{1H} and 195Pt{1H} NMR spectroscopy and crystal structure of [PtCl(bdtp)](BPh4) [bdtp = 1,5-bis(3,5-dimethyl-1-pyrazolyl)-3-thiapentane

Abstract

Treatment of the ligand 1,5-bis(3,5-dimethyl-1-pyrazolyl)-3-thiapentane (bdtp) with several platinum starting materials, such as K2PtCl4, PtCl2, [PtCl2(CH3CN)2] and [PtCl2(PhCN)2], have been developed under different conditions. The reactions did not yield pure products. The ratio of the NSN, NS and NN isomers has been calculated through NMR experiments. Subsequent treatment of the mixtures of complexes with NaBPh4 gave [PtCl(bdtp)](BPh4) (1). These Pt(II) complexes were characterised by elemental analysis, conductivity measurements, IR spectroscopy and 1H, 13C{1H} and 195Pt{1H} NMR spectroscopy. A mixture of complexes was again obtained when the complex [PtCl(bdtp)](BPh4) was heated under reflux in a solution of Et4NBr in CH2Cl2/MeOH (1:1). This proves the hemilability of the ligand bdtp with Pt(II). The X-ray crystal structure of the complex [PtCl(bdtp)](BPh4) was determined. The crystal structure contains two kinds of discrete [PtCl(bdtp)]+ cations, two BPh4- anions and two acetonitrile solvent molecules. In both cations the metal atom is tri-coordinated by the two azine nitrogen atoms and one thioether sulfur atom of the thioether-pyrazole ligand, its coordination (distorted square planar) being completed with one chlorine atom.