Binuclear organotin(IV) complexes with adipic dihydrazones: Synthesis, spectral characterization, crystal structures and antibacterial activity

Abstract

New organotin(IV) complexes, (R2Sn)2L [L = La: R = Me (1), Ph (2); L = Lb: R = Me (3), Ph (4)] have been synthesized by reaction of dihydrazone ligands, bis(5-bromosalicylaldehyde) adipicdihydrazone (H4La) and bis(2-hydroxynaphthaldehyde) adipicdihydrazone (H4Lb) with R2SnCl2 (R = Me or Ph). The synthesized compounds have been investigated by elemental analysis and IR, 1H NMR, and 119Sn NMR spectroscopy. The structures of 1 and 4 have been also confirmed by X-ray crystallography. The results show that the dihydrazone acts as a tetrabasic ligand in the enolic form and is coordinated to two diorganotin moiety via the imine nitrogen and phenolic and enolic oxygen atoms. All complexes are binuclear and the coordination number of each tin is five. The in vitro antibacterial activity of ligands and complexes has been evaluated against Gram-positive (Bacillus subtilis and Staphylococcus aureus) and Gram-negative (Escherichia coli and Pseudomonas aeruginosa) bacteria and compared with standard drugs. All complexes exhibit more inhibitory effects than the parent ligands.