Synthesis, Structure, and Magnetic and Biological Properties of Copper(II) Complexes with 1,3,4-Thiadiazole Derivatives.

New coordination compounds of copper(II) with 2,5-bis(ethylthio)-1,3,4-thiadiazole (L) and 2,5-bis(pyridylmethylthio)-1,3,4-thiadiazole (L) with compositions Cu(L)Br, Cu(L)(CN), Cu(L)Cl, and Cu(L)Br were prepared. The complexes were identified and studied by CHN analysis, infrared (IR) spectroscopy, powder X-Ray diffraction (XRD), and static magnetic susceptibility. The crystal structures of Cu(II) complexes with L were determined. The structures of the coordination core of complexes Cu(L)Cl and Cu(L)Br were determined by Extended X-ray absorption fine structure (EXAFS) spectroscopy. Magnetization measurements have revealed various magnetic states in the studied complexes, ranging from an almost ideal paramagnet in Cu(L)Br to alternating-exchange antiferromagnetic chains in Cu(L)(CN), where double dicyanamide bridges provide an unusually strong exchange interaction (J/k ≈ -23.5 K; J/k ≈ -20.2 K) between Cu(II) ions. The cytotoxic activity of copper(II) complexes with L was estimated on the human cell lines of breast adenocarcinoma () and hepatocellular carcinoma ().