New mono- and binuclear Pd(II) complexes containing 1,2,4-triazole moieties

The reaction of AMTT (AMTT = 4-amino-3-methyl-1,2,4-triazol-5-thione, HL1) with palladium(II) chloride and triphenylphosphane as a co-ligand in acetonitrile afforded the mononuclear PdII-complex [(PPh3)Pd(HL1)Cl]Cl·2CH3CN (1). The complex [(PPh3)Pd(HL1)I]Cl·1/2H2O (2) was prepared via halogen exchange between 1 and sodium iodide in methanol/acetonitrile. The first binuclear palladium(II) complex containing singly deprotonated HL1, [(PPh3)2ClPd(L1)Pd(PPh3)Cl]Cl·1/3H2O·CH3OH (3), was prepared by the reaction of HL1 with palladium(II) chloride and triphenylphosphane in the presence of sodium acetate in methanol.All the complexes have been characterized by a combination of FT-IR-, 31P NMR-spectroscopy, elemental analyses and mass spectrometry. The molecular structures of the complexes were determined by X-ray diffraction studies. The unit cell of 2 exhibits two crystallographically independent complexes, while the unit cell of 3 contains three crystallographically independent molecules. While the triazole moiety in 1 and 2 acts as a bidentate chelating ligand, the deprotonated triazole compound in 3 acts as a bridging agent between two metal centers. Single-crystal X-ray diffraction revealed that the packing mode of the heterocycle by the phenyl rings of the PPh3 moiety is responsible for the interesting observed “sandwich” effect. The X-ray structure of the complex [Pd(py)4]Cl2·1/2H2O (4) is also reported.

Three Pd(II) complexes containing 4-amino-3-methyl-1,2,4-triazol-5-thione (HL1), [(PPh3)Pd(HL1)Cl]Cl.2CH3CN (1), [(PPh3)Pd(HL1)I]Cl.1/2H2O (2) and [(PPh3)2ClPd(L1)Pd(PPh3)Cl] Cl·1/3H2O·CH3OH (3) have been synthesized and characterized. 3 shows the formation of an interesting “sandwich” effect due to the arrangement of phenyl rings.Figure optionsDownload as PowerPoint slide