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

Abstract

When dpktch was allowed to react with HgCl 2 in acetonitrile under reflux, [HgCl 2(κ 2-N,N′-dpktch)] was isolated in good yield. Infrared spectra disclosed the absence of Hg O coordination and 1H NMR studies in d 6-dmso revealed that [HgCl 2(κ 2-N,N′-dpktch)] is sensitive to its environment and that its amide proton is exchangeable. Electronic absorption spectral measurements confirmed the sensitivity of [HgCl 2(κ 2-N,N′-dpktch)] to changes in its surroundings. In an aprotic solvent such as CH 2Cl 2, a single intra-ligand-charge-transfer transition (ILCT) due to [HgCl 2(κ 2-N,N′-dpktch)] appeared, and in a protophilic solvent, two intra-ligand-charge-transfer transitions appeared due to [HgCl 2(κ 2-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 HgCl 2, and dpktch. X-ray crystallographic studies on a triclinic, P 1 ¯ single crystal of [HgCl 2(κ 2-N,N′-dpktch)] show the N,N′-coordination of dpktch and the extended structure revealed polymeric stacks of anti-parallel sheets of [HgCl 2(κ 2-N,N′-dpktch)] stabilized by a web of non-covalent bonds that include π–π stacking, hydrogen bonds, and short non-hydrogen intermolecular interactions.