Synthesis and Structural Characterization of Picolinoyl (4-ethylthiosemicarbazide) and its New Heteroleptic Cu(II) Complex

The ligand picolinoyl(4-ethylthiosemicarbazide) HL was synthesized by the reaction of picolinohydrazide and ethyl isothiocyanate in absolute ethanol. The structure of HL was characterized by spectroscopic methods such as IR, 1H, and 13C NMR spectroscopy. One-pot reaction of CuCl2 and equimolar amounts of HL and o-phenanthroline in CH2Cl2/MeOH mixture with the presence of a supporting base like pyridine gave rise to a new heteroleptic cationic Cu(II) complex with the composition of [Cu(L)(o-phen)]+. Crystalline PF6– salt was obtained after workup with (n-Bu4N)(PF6) and single-crystal structure of the complex was determined. The spectroscopic data and X-ray crystallography demonstrated that the Cu(II) ion is five-coordinate with the coordination sphere consisted of (S, N1, Npyridine) and (N, N) donor sets belonging to the singly deprotonated ligand {L–} and o-phenanthroline, respectively.