Di- and tri-organotin(IV) complexes derived from aryltelluronic acids: Synthesis, structural characterization and in vitro cytotoxicities

• Six new organotin(IV) complexes with 3,4-dimethylbenzenetelluronic acid and 3,5-dimethylbenzenetelluronic acid.
• Complexes 1 and 4 exist a centrosymmetric 8-member macrocyle Sn2Te2O4 dipping perpendiculared to the Te2O2 ring.
• Complexes 1–6 were tested for cytotoxic assessment in vitro.

Reactions of R2SnCl2 (R = Me) or R3SnCl (R = Me, Ph) with the respective dinuclear aryltellurinic acid (H6L1 = [3,4-Me2C6H3TeO(OH)3]2 and H6L2 = [3,5-Me2C6H3TeO(OH)3]2) afforded two types of aryltelluronic organotin esters: [R2Sn(CH3OH)(R2SnCl)]2L (L1 = [3,4-Me2C6H3TeO4]2, R = Me: 1; L2 = [3,5-Me2C6H3TeO4]2, R = Me: 4) and [(R3Sn)2H]2L (L1 = [3,4-Me2C6H3TeO4]2, R = Me: 2, R = Ph: 3; L2 = [3,5-Me2C6H3TeO4]2, R = Me: 5, R = Ph: 6). All the complexes were characterized by means of elemental analysis, FT-IR, and NMR (1H, 13C, 119Sn) spectroscopy as well as X-ray crystallography. Single crystal X-ray diffraction shows that they are isostructural and crystallized as Sn4Te2 molecules, in which an almost planar four-membered Te2(μ2-O)2 units are situated in the center. Moreover, what is novel about 1 and 4 is that there exists a centrosymmetric 8-member macrocyle containing Sn2Te2O4 dipping perpendiculared to the Te2O2 ring. The geometry of the tellurium atom is described as a distorted octahedron, and tin atoms are best described as distorted tetrahedron and distorted trigonal bipyramid. Through intermolecular weak interactions, both complexes 1 and 4 have two dimensional network structures and complex 2 shows one dimensional infinite polymeric chain structure. Furthermore, in vitro cytotoxicities of complexes 1–6 were also evaluated, using human lung cancer cells (A549) and human hepatocellular carcinoma cells (HepG2).

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