Novel mixed-ligands Pt(II) complexes: synthesis, multinuclear magnetic resonance and crystal structures of cis- and trans-Pt(sulfoxide)(pyrimidine)Cl2

New types of mixed-ligands Pt(II) complexes, cis- and trans-Pt(R2SO)(pyrimidine)Cl2, were synthesized and characterized by IR and multinuclear magnetic resonance spectroscopies and by crystallographic methods. Compounds with R2SO=dimethylsulfoxide (DMSO), tetramethylenesulfoxide (TMSO), di-n-propylsulfoxide (DPrSO), di-n-butylsulfoxide (DBuSO), dibenzylsulfoxide and diphenylsulfoxide were studied. The aqueous reaction of K[Pt(R2SO)Cl3] with pyrimidine (pm) in a 1:1 ratio produced trans-Pt(R2SO)(pm)Cl2, which can isomerize to the cis isomer in an organic solvent. The 195Pt NMR resonances of the trans complexes were observed at higher field (ave. −3079 ppm) than the cis analogues (ave. −2932 ppm). The 195Pt coupling constants with the pyrimidine atoms 3J(195Pt1H) and 3J(195Pt13C) are larger in the cis configuration (∼40 Hz) than in the trans analogues (∼30 Hz). One ν(PtCl) vibration was observed for the trans compounds, while two such bands were observed for the cis isomers. The crystal structures of cis-Pt(R2SO)(pm)Cl2 (R2SO=DMSO, TMSO, DPrSO and DBuSO) and of trans-Pt(TMSO)(pm)Cl2 were determined. The trans influence of the three different ligands was compared.