Electrochemical synthesis and structural characterisation of zinc, cadmium and mercury complexes of heterocyclic bidentate ligands (N, S)Dedicated to the memory of Professor C. A. McAuliffe, a good friend and a teacher.

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.