Polynuclear diorganotin(IV) complexes with arylhydroxamates: Syntheses, structures and in vitro cytotoxic activities

Series of polynuclear diorganotin(IV) complexes with di-halogenbenzohydroxamate ligands (substituents = 2,4-Cl2, 2,4-F2, 3,4-F2, 2,5-F2, 2,6-F2), formulated as the polymeric [R2SnL]na (1:1) and the tetranuclear [R4Sn2(HL)2(L)]2b (2:3) (HL = arylhydroxamate), were prepared and characterized by FT-IR, 1H, 13C, 119Sn NMR spectroscopies, elemental analyses and melting point measurements. X-ray diffraction analyses were also carried out for the representative complexes [Me2Sn{2,4- F2C6H3C(O)NO}]n2a and [n-Bu4Sn2{2,4- F2C6H3C(O)NHO}2 {2,4-F2C6H3C(O)NO}] 21b and show that the ligated mono- and di-basic forms, HL and L, of the arylhydroxamic acid (H2L) display the oxamic and oximic tautomeric forms, respectively. These compounds exhibit in vitro cytotoxicities toward 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 polymeric diorganotin/hydroxamato complexes a containing the long carbon chain butyl ligands are the most active ones, and the dependence of the antitumor activity of the complexes on various factors, namely the nuclearity, the organic ligand, the type, position and number of the X ring substituents, is also discussed.