Synthesis, characterization, crystal structure and electrochemistry of a novel palladium(II) binuclear complex containing 1,2,4-triazole bis(4-phenylthiosemicarbazone) bridges

A new bis(thiosemicarbazone) ligand, H5L1, derived from 3,5-diacyl-1,2,4-triazole and 4-phenylthiosemicarbazide has been prepared. Treatment of this ligand with Li2[PdCl4] produced the binuclear palladium(II) compound, [Pd2(μ-H3L1)2]. The compounds were characterized by elemental analyses (C, H, N, S), mass spectrometry, IR, UV–Vis and 1H NMR spectroscopy and electrochemical techniques. The crystal and molecular structure of [Pd2(μ-H3L1)2] · 4DMSO · H2O with dideprotonation of triazolic and thiosemicarbazone NH groups has been determined by single X-ray diffraction. The H5L1 ligand coordinates, in a dideprotonated form, to the palladium ions in a new tridentate fashion (SNN) and S-bridging bonding modes. Thus, the molecular units of the palladium complex are stacked as dimers.