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

Abstract

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 Pd II-complex [(PPh 3)Pd( HL1)Cl]Cl·2CH 3CN ( 1). The complex [(PPh 3)Pd( HL1)I]Cl·1/2H 2O ( 2) was prepared via halogen exchange between 1 and sodium iodide in methanol/acetonitrile. The first binuclear palladium(II) complex containing singly deprotonated HL1, [(PPh 3) 2ClPd( L1)Pd(PPh 3)Cl]Cl·1/3H 2O·CH 3OH ( 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 PPh 3 moiety is responsible for the interesting observed “sandwich” effect. The X-ray structure of the complex [Pd(py) 4]Cl 2·1/2H 2O ( 4) is also reported.