Electrochemical synthesis and structural characterisation of zinc, cadmium and mercury complexes of heterocyclic bidentate ligands (N, S)

Abstract

The electrochemical oxidation of anodic metal (zinc or cadmium) in acetonitrile solutions of 3-trifluoromethylpyridine-2-thione (3-CF₃-pySH) or 5-trifluoromethylpyridine-2-thione (5-CF₃-pySH) affords complexes [M(R-pyS)₂], M = Zn, Cd, R = 3-CF₃, 5-CF₃. Adducts of these compounds with 2,2′-bipyridine (bipy) or 1,10-phenanthroline (phen) were also obtained when the bidentate coligand was present in the cell. On the other hand, reaction of a methanol solution of mercury acetate with the corresponding pyridine-2-thione in the presence of triethylamine affords compounds of composition [Hg(R-pyS)₂]. All the compounds obtained have been characterised by microanalysis, IR spectroscopy and, in cases where the compound was sufficiently soluble, by ¹H, ¹³C and ¹⁹⁹Hg NMR spectroscopy. The compounds [Zn(3-CF₃-pyS)₂(bipy)] (1), [Zn(3-CF₃-pyS)₂(phen)]·CH₃CN (2), [Zn(5-CF₃-pyS)₂(bipy)] (3), [Cd(3-CF₃-pyS)₂(DMF)]₂ (4), [Cd₂(5-CF₃-pyS)₄(DMF)]_n (5), [Cd(3-CF₃-pyS)₂(bipy)]·CH₃CN (6), [Hg(3-CF₃-pyS)₂] (7) and [Hg(5-CF₃-pyS)₂] (8) were also characterised by X-ray diffraction.