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)

Abstract

Abstract. 2-mercaptonicotinic acid (H 2 mna = 2-HS(C 5 H 3 N)COOH) gave a thiolato compound of the formula Hg(Hmna) 2 by a reaction with various mercury(II) salts, HgX 2 (X = Cl − , Br− , 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.1 H and 13 C NMR measurements provided additional information on the thiol-thione tautomerism in H 2 mna and Hg(Hmna) 2 and also on the binding mode to mercury in the DMSO-d 6 solution. HgBr 2 (CH 3 -Hmna) 2 was obtained from the reaction of H 2 mna with HgBr 2 in methanol after filtering off the main product Hg(Hmna) 2 (CH 3 -Hmna = 2-HS(C 5 H 3 N)COOCH 3 ). The crystal structures of H 2 mna and HgBr 2 (CH 3 -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 CH 3 -Hmna ligands form a tetrahedral coordination sphere around the mercury atom in HgBr 2 (CH 3 -Hmna) 2 .