Synthesis, X-ray crystal structures and multinuclear NMR characterization of Hg(II) complexes of 2-[( E)-2-(aryl)-1-diazenyl]pyridine

Abstract

Syntheses and structural studies for the two complexes dichloro-{2-[( E)-2-(4-methylphenyl)-1-diazenyl]pyridine}Hg(II) ( 1) and dichloro-{2-[( E)-2-(3-methylphenyl)-1-diazenyl]pyridine}Hg(II) ( 2) are reported. The solid-state structures of the complexes were determined by X-ray diffraction methods and in addition, the complexes were characterized in solution using 1H, 13C and 199Hg NMR spectroscopy. The X-ray structures reveal that the complexes adopt surprisingly different structures. Complex 2 has an extended polymeric structure with 2-[( E)-2-(3-methylphenyl)-1-diazenyl]pyridine behaving as a monodentate ligand via the pyridyl nitrogen, and all the chlorine atoms serving to bridge mercury atoms, whereas complex 1 has a dimeric structure with 2-[( E)-2-(4-methylphenyl)-1-diazenyl]pyridine behaving as a bidentate ligand via the pyridyl nitrogen and one of the azo nitrogens, with a terminal chlorine on each Hg and a μ,μ′-dichloro bridge between the mercury atoms. But the coordination geometry around the mercury atom is similar in both complexes, each showing a distorted trigonal bipyramidal arrangement of the donor atoms. These complexes were characterized in solution by 1H, 13C, 199Hg NMR spectroscopy.