Diorganotin(IV) complexes with furan-2-carbohydrazone derivatives: synthesis, characterization, crystal structure and antibacterial activity

Four new diorganotin(IV) complexes, R2SnL (L=La: R=Me 1, Ph 2; L=Lb: R=Me 3, and Ph 4), have been synthesized by reaction of hydrazone ONO donors, 5-bromo-2-hydroxybenzaldehyde furan-2-carbohydrazone (H2La) and 2-hydroxynaphthaldehyde furan-2-carbohydrazone (H2Lb) with diorganotin(IV) dichloride in the presence of a base. The compounds have been investigated by elemental analysis and IR, 1H NMR, and 119Sn NMR spectroscopies. Spectroscopic studies show that the hydrazone is a tridentate dianionic ligand, coordinating via the imine nitrogen and phenolic and enolic oxygens. The structures of H2Lb and 3 have also been confirmed by X-ray crystallography. The results show that the structure of 3 is a distorted square pyramid with imine nitrogen in apical position. The in vitro antibacterial activities of ligands and complexes have been evaluated against gram-positive (Bacillus cereus and Staphylococcus aureus) and gram-negative (Escherichia coli and Pseudomonas aeruginosa) bacteria. H2La and H2Lb show no activity but the diphenyltin(IV) complexes exhibit good activities towards two bacterial strains in comparison with standard bacterial drugs.