Ni(II), Pd(II) and Cu(II) complexes with N-(dialkylthiocarbamoyl)-N′-picolylbenzamidines: Structure and activity against human MCF-7 breast cancer cells

Abstract: N-(Dialkylthiocarbamoyl)-N′-picolylbenzamidines (HLEt and HLMorph) react with NiCl2, CuCl2 and [PdCl2(MeCN)2] with the formation of complexes of the general composition [M(LR)Cl] (M=Ni (1), Pd (2)) and the dimeric complexes [{Cu(LR)Cl}2] (3). The molecular structures of complexes 1 and 2 exhibit a square-planar coordination sphere, in which the organic ligands coordinate in a S,N,N coordination mode. The two subunits of 3, the arrangement of each is similar to those of 1 and 2, are connected via two weak Cu–Cl′ bonds. The copper complexes [{Cu(LR)Cl}2] (3) are slowly oxidized under aerobic conditions to give [{Cu(∗LR)Cl}2] complexes (4), where H∗LR =N-(dialkylthiocarbamoyl)-N′-picolinoylbenzamidines. Complexes 1 and 2 show a very weak reduction of the growth of human MCF-7 breast cancer cells. Complexes 4, however, possess a remarkable cytotoxicity with IC50 values within the range 0.40–1.05μM. Compounds 3 are likely converted to 4 under the conditions of the cytotoxicity assay, and consequently exhibit IC50 values very similar to those found for 4. [Copyright &y& Elsevier]