Synthesis, structural characterization and cytostatic properties of N,N-dicyclohexyldithiooxamide complexes of antimony(III) halides (SbX3, X: Br or I)

The novel antimony(III) halide complexes with the bi-dentate substituted dithiooxamide ligand, N,N-dicyclohexyldithiooxamide (HDTOA) of formulae {[SbBr3(HDTOA)1.5]}n (1) and {[SbI3(HDTOA)1.5].C6H6}n (2), were prepared by reacting antimony(III) bromide or antimony(III) iodide with HDTOA in 1:1 molar ratio. The compounds were characterized by their m.p., FT-IR spectroscopy, Raman spectroscopy, 1H, 13C NMR spectroscopy, Thermal Gravimetric – Differential Thermal Analysis (TG-DTA) and single crystal X-ray diffraction analysis. Both complexes are polymeric consisting by [SbX3(HDTOA)1.5] building blocks. The octahedral geometric demand of the metal center is covered by three halides and three sulfur atoms from three different HDTOA ligands with facial conformation in both complexes. Each ligand bridged two metal centers of two units, through sulfur donor atoms, acting as bi-dentate bridging ligand. Complexes 1 and 2 were also tested for in vitro cytotoxic activity against human breast adenocarcinoma (MCF-7) and human cervical adenocarcinoma (HeLa) cells. Principal components analysis (PCA) was performed to discriminate the significant physicochemical molecular descriptors while regression analysis successfully related the experimental inhibitory concentrations, (IC50) to the independent variables indexed by PCA. The calculated IC50 values are satisfactorily compared with the measured inhibitory activity of the complexes.

Graphical abstractTwo new polymeric complexes of formula {[SbX3(HDTOA)1.5]}n (X = Br, I) were synthesized and characterized. The in vitro cytotoxic activity against MCF-7 and HeLa cell lines were evaluated. Correlation of the experimental ID50 values with six parameters is performed by PLS regression analysis, indicating that the type of the ligand is crucial for the cytotoxicity of this type of complexes against MCF-7 cells.Figure optionsDownload full-size imageDownload as PowerPoint slide