Transition metal complexes ML2 (2–6) [where\ud
M = Ni(II), Cu(II), Zn(II), Cd(II), Pd(II) and HL = allyl-2-\ud
(4-benzyloxyphenylmethylene)hydrazine carbodithioate (1)]\ud
have been prepared by the reaction of the ligand with metal\ud
ions in 2:1 molar ratio and characterized by physicochemical\ud
techniques and spectroscopic methods. The crystal\ud
structures of the free ligand and its nickel(II) complex 2 have\ud
been determined by X-ray diffractometry. The ligand exists\ud
in its thione tautomeric form both in solution and in the solid\ud
state. In complex 2, square-planar coordination of nickel(II)\ud
was achieved by two chelating ligand moieties coordinating\ud
through the azomethine nitrogen and the deprotonated thione\ud
sulphur atom. Based on the crystal structures of analogous\ud
dithiocarbazate species, a square-planar geometry was assumed for the copper(II) and palladium(II) complexes,\ud
and a tetrahedral coordination sphere for the zinc(II) and\ud
cadmium(II) derivatives. The in vitro bactericidal activity\ud
suggests that the palladium(II) complex is strongly active\ud
against two bacteria. The cadmium(II) complex is moderately\ud
cytotoxic with an LC50 value of 409 lg/ml, but less\ud
active than gallic acid, LC50 = 78 lg/ml