S-allyl-3-(2-pyridyl-methylene)dithiocarbazate ligand and its manganese(II), cobalt(III) and nickel(II) complexes

A new NNS tridentate ligand, S-allyl-3-(2-pyridyl-methylene)dithiocarbazate (HL) has been prepared. Three coordination complexes, Mn(L)2 (1), [Co(L)2]NO3 (2) and Ni(L)2 (3) (L− is the deprotonated monoanionic form of HL) have been synthesized and characterized by elemental analysis, molar conductivity, FT-IR, 1H NMR and UV–Vis spectroscopy. 1 and 3 are neutral complexes, while 2 is cationic with nitrate as the counter ion. Single crystal X-ray diffraction analysis shows that bis-chelate complexes have a distorted octahedral geometry in which two ligands in thiolate tautomeric form coordinate to the metal center through N atoms of the pyridine and imino moieties and one S atom. Molecular geometry from X-ray analysis, molecular geometry optimization, atomic charges distribution and bond analysis of the ligand and complexes have been performed using the density functional theory (DFT) with the B3LYP functional.