Synthesis and characterization of cyclopalladated and non-cyclopalladated complexes of ligands containing the 1,3-bis(thiomethyl)benzene unit

The reactivity of [Pd(CH3CN)2)Cl2] toward the ligands 1,3-bis(ethylthiomethyl)benzene (HL1), 1,3-bis(benzylthiomethyl)benzene (HL2), 1,3-bis(phenylthiomethyl) benzene (HL3) and dimethyl 2,2′-[1,3-phenylenebis(methylthio)]-dibenzoate (HL4) has been investigated. In all cases the reaction of the palladium(II) salt with the corresponding ligand in acetonitrile at room temperature afforded the simple non-cyclopalladated complex. Analytical and spectroscopic data of these complexes suggest that the two sulfur atoms of the ligands and two chlorine atoms coordinate simultaneously to the palladium ion defining monomeric species. Cyclopalladated complexes of ligands HL1 - HL4 have been obtained by refluxing their non-cyclopalladated derivatives in acetonitrile or by direct reaction of the starting materials in the same solvent at refluxing temperature. Different reaction times have been found depending on the ligand. Cyclopalladated complexes of ligands HL1, HL2 and HL4 have been characterized by X-ray diffraction methods. All of them display square-planar coordination around the palladium atom provided by the rigid S2C chelating moiety of the 1,3-bis(thiomethyl)benzene unit and the chlorine atom which is located in a trans position with respect to the Pd - C bond. Copyright © 1996 Elsevier Science Ltd.