This work stemmed from our interest for the quest of finding suitable extractants for removal of both organic and inorganic mercury from nuclear defense waste at Savannah River Site (SRS). In our exploration to develop suitable chelates towards mercury removal by complexation, we have examined reactions of various N, N- and N, S-donor ligands with Hg(II) salts, such as HgCl2 and Hg(CH3COO)2. Inspired by the biochemical mechanism of Hg(II) interactions with S-containing proteins, we have utilized a ligand bearing thioamide groups, namely, bis(phenyl)pyridine-2,6-carbothioamide, to examine its Hg(II) binding capacity. In solution, formation of this complex is monitored with the aid of 1H NMR and UV-Vis titration experiments. This ligand also exhibits selectivity towards Hg(II) in presence of competing metal ions. X-ray structure revealed a unusual dinuclear mercury(II) complex. The X-ray structure along with the 1NMR titration experimet corrobotated the same structure in solid state and solution respectively. C, H, N elemental analysis also supported this finding. In another approach, we have examined reactions of various substituted pyrazoles with Hg(II) salts. Pyrazole derived complexes are usually quite stable and the 3-, 4-, and 5-positions on this heterocyclic ligand offer the amenability for functionalization with different groups, dictating the structural diversity and properties of the resulting complexes. Herein we also describe the synthesis and structures of a diverse family of Hg(II) complexes derived from pyrazoles bearing different functional groups on 3-, 4- and 5-positions. Based on steric and electronic properties of these pyrazoles, Hg(II) complexes of varied nuclearity have been isolated. All possible coordination numbers (from CN = 2 - 6) around Hg (II) centers have been recognized within this group of complexes.

Mercury (II) complexes derived from N, N- and N, S-donor ligands

2019 Spring National Meeting

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