Synthesis, Spectral and Thermal Characterization of Bis(pyridine-3- carboxy-2-thiolato-S)mercury(II). Crystal Structure of Dibromobis(3- metoxycarbonylpyridine-2-thiolato-S)mercury(II)

2-mercaptonicotinic acid (H2mna = 2-HS(C5H3N)COOH) gave a thiolato compound of the formula Hg(Hmna)2 by a reaction with various mercury(II) salts, HgX2 (X = Cl−, Br−, I−, SCN−) in an ethanol or methanol solution irrespectively of the molar ratio of the reactants (1:1 or 1:2). The same compound was obtained from the reaction of mercury(II) acetate in an aqueous-ethanol solution. Hg(Hmna)2 was characterized by vibrational spectroscopy and thermal analysis. 1H and 13C NMR measurements provided additional information on the thiol-thione tautomerism in H2mna and Hg(Hmna)2 and also on the binding mode to mercury in the DMSO-d6 solution. HgBr2(CH3-Hmna)2 was obtained from the reaction of H2mna with HgBr2 in methanol after filtering off the main product Hg(Hmna)2 (CH3-Hmna = 2- HS(C5H3N)COOCH3). The crystal structures of H2mna and HgBr2(CH3-Hmna)2 were determined by the X-ray structure analysis. 2-mercaptonicotinic acid exists in the crystalline state in the thione tautomeric form. Two bromine atoms and two S-bound CH3-Hmna ligands form a tetrahedral coordination sphere around the mercury atom in HgBr2(CH3-Hmna)2.(doi: 10.5562/cca2169