Equimolar reactions of dibutyltin(IV) oxide with Schiff bases derived from amino‐acids led to the formation of a new series of dibutyltin(IV) complexes of general formula, Bu2SnL [L=dianion of tridentate Schiff bases derived from the condensation of 2‐hydroxy‐1‐naphthaldehyde or acetyl acetone with glycine (L‐1), L‐β‐alanine (L‐2), DL‐valine (L‐3), DL‐4‐aminobutyric acid (L‐4), L‐methionine (L‐5), L‐leucine (L‐6) and phenylglycine (L‐7)]. An attempt has been made to prove the structures of the resulting complexes on the basis of elemental analyses, conductance measurements and electronic, IR, multinuclear magnetic resonance (1H, 13C and 117Sn) and 119Sn Mössbauer spectral studies. The complexes have been tested against various bacteria [Streptococcus faecalis, Klebsiella pneumoniae, Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus penicillin resistance (2500 units)] and fungi (Candida albicans, Cryptococcus neoformans, Sporotrichum schenckii,Trichophyton mentagrophytes and Aspergillus fumigatus). All the complexes showed moderate activity. The cytotoxicity of a few compounds has been screened in vitro against seven human tumour cell lines, viz. MCF‐7, EVSA‐T, WiDr, IGROV, M19 MEL, A498 and H226. The activities found experimentally were better than those obtained for cisplatin and carboplatin © 1997 John Wiley & Sons, Ltd.

The crystal structure of di-n-butyltin pyridine-2-phosphonate-6-carboxylate, [C14H24NO6PSn]2, features centrosymmetric dimers disposed about a central Sn2O2 core. The phosphonate carboxylate dianion is μ2-tetradentate, coordinating one tin atom via one of the phosphonate oxygen atoms, the pyridine nitrogen atom, and one of the carboxylate oxygen atoms; the latter atom also coordinates the second tin atom of the dimer. The remaining positions in the seven-coordinate, distorted pentagonal bipyramidal geometry are occupied by a water molecule and two n-butyl groups that occupy axial positions. The lattice is stabilized by hydrogen-bonding contacts leading to an arrangement of parallel, orthogonally related chains of dimeric units. In methanol solution, the dimer is involved in a dissociation equilibrium that is fast on the NMR time scale.

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