Novel Organotin(IV) Complexes of 2-[4-Hydroxy-3-((2-hydroxyethylimino)methyl)phenylazo]benzoic Acid: Synthesis, Structure, Noncovalent Interactions and In Vitro Antibacterial Activity

Three new organotin(IV) complexes, [Me3Sn(H2L)]2 (1), Bu3Sn(H2L) (2), and [(Bu2Sn(H2L))2O]2 (3) were synthesized by the reaction of 2-[4-hydroxy-3-((2-hydroxyethylimino)methyl)phenylazo]benzoic acid (H3L) with appropriate alkyltin(IV) precursors. The complexes were characterized by elemental analysis, IR, and multinuclear (1H, 13C and 119Sn) NMR spectroscopy. Further, the complex 1 was analyzed by single-crystal X-ray analysis. It displays a 24-membered cyclic dimeric Me3SnIV(H2L) unit where the ligand act as a bridging framework using its carboxylate-O and phenoxy-O atoms. The Sn(IV) adopts distorted trigonal-bipyramidal geometry. In the solution state, the structures were determined by 119Sn-NMR spectroscopy, and the complexes 1 and 2 have distorted tetrahedral geometry, whereas complex 3 shows distorted trigonal-bipyramidal geometry around the tin centres. The Hirshfeld surface analysis and DFT calculations, together with a topological analysis of the electron density distribution in the crystal structure of complex 1, indicate that its molecular packing determined by various noncovalent interactions, including stacking and hydrogen bonding. The antibacterial studies of the ligand and the complexes (1–3) against gram-negative bacteria viz. Klebsiella pneumoniae (A),Vibrio cholerae (M) and Shigella boydii (Q) and gram-positive bacteria viz.Staphylococcus aureus (J), Streptococcus pneumonia (K) are promising and the compounds can be treated as potential common antibacterial materials.