Synthesis, characterization and biological activity of diorganotin complexes with ONO terdentate Schiff base

Diorganotin(IV) complexes with general formula R2SnL [H2L = (E)-N′-[1-(5-bromo-2-hydroxyphenyl)ethylidene]-3-hydroxy-2-naphthohydrazide (H2L1) and (E)-N′-[1-(5-chloro-2-hydroxyphenyl)ethylidene]-3-hydroxy-2-naphthohydrazide (H2L2); R = Me, Bu, Ph, Cy, Bz, o-ClBz and p-ClBz (1–14)] have been synthesized and characterized by IR, 1H, 13C and 119Sn NMR spectroscopic techniques and single crystal X-ray diffractometry. The structure of the complexes, {[1-(5-bromo-2-oxidophenyl)ethylidene]-3-hydroxy-2-naphthohydrazidato}dimethyltin(IV), 1, {[1-(5-chloro-2-oxidophenyl)ethylidene]-3-hydroxy-2-naphthohydrazidato}dimethyltin(IV), 8 and {[1-(5-chloro-2-oxidophenyl)ethylidene]-3-hydroxy-2-naphthohydrazidato}dicyclohexyltin(IV), 11 reveals a five-coordinated, trigonal–bipyramidal geometry, whereby the trigonal plane of the complexes consists of the imine nitrogen atom and alkyl groups from the diorganotin moieties. The complexes are stabilized by a strong intramolecular hydrogen bonding between N(2) and O(3)–H(3). The Schiff bases and their corresponding diorganotin(IV) complexes have been evaluated against three human carcinoma cell lines, namely HT29 (human colon carcinoma cell line), SKOV-3 (human ovarian cancer cell line) and MCF7 (hormone-dependent breast carcinoma cell line), for their cytotoxic activities. The dimethyltin derivatives and dibutyltin derivatives of the Schiff base ligands display good cytotoxic activities against the tested cell lines.