Synthesis, structures and spectroscopic properties of some tin(IV) complexes of the 2-acetylpyrazine Schiff bases of S-methyl- and S-benzyldithiocarbazates

Tin(IV) complexes of formulae, [Sn(acpysme)(C6H5)(2)Cl], [Sn(acpysbz)(C6H5)(2)Cl], [Sn(acpysbz)(C6H5)Cl-2] and [Sn(acpysbz)I-3] (acpysme and acpysbz = anionic forms of the 2-acetylpyrazine Schiff bases of S-methyldithiocarbazate and S-benzyldithiocarbazate, respectively) have been synthesized and structurally characterized by a variety of physico-chemical techniques and X-ray diffraction measurements. In all these complexes the tin atom adopts a distorted octahedral geometry with the Schiff bases coordinating with the tin(IV) ion as uninegatively charged tridentate NNS chelating agents via one of the pyrazine nitrogen atoms, the azomethine nitrogen atom and the thiolate sulfur atom. In the [Sn(NNS)Ph2Cl] complexes, the three NNS donor atoms of the Schiff base and a chloride ion occupy equatorial positions whereas the two phenyl groups take up axial positions of a distorted octahedron. The complexes, [Sn (acapsbz)(Ph)Cl-2] and [Sn(acapsme)I-3] have also distorted octahedral configurations but in this case the halido ligands are in axial positions. The Schiff bases, Hacapsme and Hacapsbz and the complex, [Sn(acpysme)I3] exhibit strong cytotoxic activity against the human breast cancer cell lines, MDA-MB-231. (C) 2016 Published by Elsevier B.V.