X-ray crystallographic, spectroscopic, and electrochemical properties of [HgCl2 (κ2-N,N′-dpktch)] (κ2-N,N′-dpktch = di-2-pyridyl ketone thiophene-2-carboxylic acid hydrazone)

When dpktch was allowed to react with HgCl2 in acetonitrile under reflux, [HgCl2(κ2-N,N′-dpktch)] was isolated in good yield. Infrared spectra disclosed the absence of HgO coordination and 1H NMR studies in d6-dmso revealed that [HgCl2(κ2-N,N′-dpktch)] is sensitive to its environment and that its amide proton is exchangeable. Electronic absorption spectral measurements confirmed the sensitivity of [HgCl2(κ2-N,N′-dpktch)] to changes in its surroundings. In an aprotic solvent such as CH2Cl2, a single intra-ligand-charge-transfer transition (ILCT) due to [HgCl2(κ2-N,N′-dpktch)] appeared, and in a protophilic solvent, two intra-ligand-charge-transfer transitions appeared due to [HgCl2(κ2-N,N′-dpktch)] and its conjugate base. Electrochemical measurements in dmf show electrochemical decomposition following redox processes, and highlight metal and ligand based redox properties due to HgCl2, and dpktch. X-ray crystallographic studies on a triclinic, P1¯ single crystal of [HgCl2(κ2-N,N′-dpktch)] show the N,N′-coordination of dpktch and the extended structure revealed polymeric stacks of anti-parallel sheets of [HgCl2(κ2-N,N′-dpktch)] stabilized by a web of non-covalent bonds that include π–π stacking, hydrogen bonds, and short non-hydrogen intermolecular interactions.