Synthesis of new platinum(II) complexes containing hybrid thioether–pyrazole ligands: Structural analysis by 1H and 13C{1H} NMR spectroscopy and X-ray crystal structures

Treatment of the ligands 1,8-bis(3,5-dimethyl-1-pyrazolyl)-3,6-dithiaoctane (bddo), 1,9-bis(3,5-dimethyl-1-pyrazolyl)-3,7-dithianonane (bddn), and 1,6-bis(3,5-dimethyl-1-pyrazolyl)-2,5-dithiahexane (bddh) with several platinum starting materials as K2PtCl4, PtCl2, [PtCl2(CH3CN)2] and [PtCl2(PhCN)2] was developed under different conditions. The reactions did not yield pure products. The ratio of the NSSN, NS, SS, NN, and 2NS isomers has been calculated through NMR experiments. Treatment of the mixtures of complexes with NaBPh4 affords [Pt(NSSN)](BPh4)2 (NSSN = bddo, bddn). These Pt(II) complexes have been characterised by elemental analyses, conductivity measurements, IR and 1H and 13C NMR spectroscopy. The X-ray structures of the complexes [Pt(NSSN)](BPh4)2 (NSSN = bddo, bddn) have also been determined. In these complexes, the metal atom is tetracoordinated by the two azine nitrogen atoms of the pyrazole rings and two thioether sulfur atoms. When the [Pt(NSSN)](BPh4)2 (NSSN = bddo, bddn) complexes were heated under reflux in a solution of Et4NBr in CH2Cl2/CH3OH (1:1), a mixture of isomers was obtained.