Synthesis, characterization and cytotoxic activity evaluation of cyclopalladated compounds containing orthometallated benzaldehydeoxime and ethylenethiourea as ligands

Abstract

The halide-bridge cleavage reaction of the [Pd(C2,N-bzox)(µ-Cl)]2 compound (bzox = benzaldehydeoxime) with ethylenethiourea (L) in the 1:2 molar ratio at room temperature yielded the cyclopalladated compound [Pd(C2,N-bzox)(Cl)(L)] (1) whose replacement of the halide group by the addition of suitable salts afforded compounds of general formulae [Pd(C2,N-bzox)(X)(L)] {X = Br- (2), I- (3)}. All compounds were characterized by melting point, elemental analyses, infrared and 1H- and 13C{1H}-NMR spectroscopies revealing the complexes formation with the oxime coordinated to Pd(II) as C,N-chelating and the ethylenethiourea as a monodentate ligand via the sulfur atom. The cytotoxicity of cyclopalladated compounds has been evaluated in vitro against murine mammary tumor cell (LM3) showing cytotoxic activity similar to cisplatin.