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

The reactions of [PtMe3(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 [PtMe3(-κS)(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 [PtMe3(OAc)(Me2CO)x] (3, x = 1 or 2) with pymtH, pytH, tztH and tptH dimeric complexes [{PtMe3(μ-)}2] (μ- = pymt, 9; pyt, 10; tzt, 11) and the tetrameric complex [{PtMe3(μ3-tpt-κS)}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 [PtMe3(pymt-κS)(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.

Graphical abstractThe reactions of [PtMe3(OAc)(bpy)] (4) and [PtMe3(OAc)(Me2CO)x] (3, x = 1 or 2) with N,S and S,S heterocyclic bioligands resulted in the formation of monomeric [PtMe3(-κS)(bpy)] (5–8), dimeric [{PtMe3(μ-)}2] (9–11) and tetrameric [{PtMe3(μ3-tpt-κS)}4] (12) platinum(IV) complexes, showing different coordination modes of the heterocyclic ligands, see the structure of [PtMe3(pymt-κS)(bpy)] (5) as an example.Figure optionsDownload full-size imageDownload as PowerPoint slideFigure optionsDownload full-size imageDownload as PowerPoint slideFigure optionsDownload full-size imageDownload as PowerPoint slideFigure optionsDownload full-size imageDownload as PowerPoint slideFigure optionsDownload full-size imageDownload as PowerPoint slide