Novel mixed-ligands Pt(II) complexes: synthesis, multinuclear magnetic resonance and crystal structures of cis- and trans-Pt(sulfoxide)(pyrimidine)Cl-2

New types of mixed-ligands Pt(II) complexes, cis- and trans-Pt(R2SO)(pyrimi dine)Cl-2, were synthesized and characterized by IR and multinuclear magnet ic resonance spectroscopies and by crystallographic methods. Compounds with R2SO = dimethylsulfoxide (DMSO), tetramethylenesulfoxide (TMSO), di-n-prop ylsulfoxide (DPrSO), di-n-butylsulfoxide (DBuSO), dibenzylsulfoxide and dip henylsulfoxide were studied. The aqueous reaction of K[Pt(R2SO)Cl-3] with p yrimidine (pm) in a 1:1 ratio produced trans-Pt(R2SO)(pm)Cl-2, which can is omerize to the cis isomer in an organic solvent. The Pt-195 NMR resonances of the trans complexes were observed at higher field (ave. -3079 ppm) than the cis analogues (ave. -2932 ppm). The Pt-195 coupling constants with the pyrimidine atoms (3)J(Pt-195-H-1) and (3)J(Pt-195-C-13) are larger in the c is configuration (similar to 40 Hz) than in the trans analogues (similar to 30 Hz). One nu (Pt-Cl) vibration was observed for the trans compounds, whi le two such bands were observed for the cis isomers. The crystal structures of cis-Pt(R2SO)(pm)Cl-2 (R2SO = DMSO, TMSO, DPrSO and DBuSO) and of trans- Pt(TMSO)(pm)Cl-2 were determined. The trans influence of the three differen t ligands was compared. (C) 2001 Elsevier Science B.V. All rights reserved.