Synthesis and characterization of platinum(IV) complexes with N, S and S, S heterocyclic ligands

Abstract

The reactions of [PtMe 3(OAc)(bpy)] ( 4) with the N, S and S, S containing heterocycles, pyrimidine-2-thione (pymtH), pyridine-2-thione (pytH), thiazoline-2-thione (tztH) and thiophene-2-thiol (tptH), resulted in the formation of the monomeric complexes [PtMe 3( ▪-κ S)(bpy)] ( ▪ = pymt, 5; pyt, 6; tzt, 7; tpt, 8), where the heterocyclic ligand is coordinated via the exocyclic sulfur atom. In contrast, in the reactions of [PtMe 3(OAc)(Me 2CO) x ] ( 3, x = 1 or 2) with pymtH, pytH, tztH and tptH dimeric complexes [{PtMe 3(μ- ▪)} 2] (μ- ▪ = pymt, 9; pyt, 10; tzt, 11) and the tetrameric complex [{PtMe 3(μ 3-tpt-κ S)} 4] ( 12), respectively, were formed. The complexes were characterized by microanalyses, 1H and 13C NMR spectroscopy and negative ESI-MS ( 12) measurements. Single-crystal X-ray diffraction analysis of [PtMe 3(pymt-κ S)(bpy)] ( 5) exhibited a conformation where the pymt ligand lies nearly perpendicular to the complex plane above the bpy ligand that was also confirmed by quantum chemical calculations on the DFT level of theory.