Mononuclear diorganotin(IV) complexes with arylhydroxamates: syntheses, structures and assessment of in vitro cytotoxicity

Two series of diorganotin(IV) complexes with dihalogenobenzohydroxamate ligands (substituents = 2,4‐Cl2, 2,4‐F2, 3,4‐F2, 2,5‐F2, 2,6‐F2), formulated as [R2Sn(HL)2] (a), and the arylhydroxamato/arylcarboxylato mixed‐ligand complexes [R2Sn(HL)(L′)] (b), were prepared and characterized by FT‐IR, 1H, 13C and 119Sn NMR spectroscopies, elemental analyses and melting point measurements. X‐ray diffraction analysis was also carried out for the complex [Me2Sn{3,4‐F2C6H3C(O)NHO}2], 1a. These compounds exhibit in vitro cytotoxic activities towards human leukemic promyelocites HL‐60, BGC‐823, BEL‐7402 and KB cell lines which, in some cases, are identical to, or even higher than, that of cisplatin. The type, position and number of the X substituents in the phenyl ring play a role in the cytotoxic activity, and complex 8a, with its 2,6‐difluorobenzohydroxamato ligand, is highly active against all tumor cells. A tentative structure–activity relationship is also described.