Synthesis, structural characterization and antimicrobial activities of diorganotin(IV) complexes with azo-imino carboxylic acid ligand: Crystal structure and topological study of a doubly phenoxide-bridged dimeric dimethyltin(IV) complex appended with free carboxylic acid groups

Abstract

Diorganotin(IV) complexes appended with free carboxylic acids were synthesized by reacting diorganotin(IV) dichlorides [R2SnCl2; R = Me (1), Bu (2) and Ph (3)] with an azo-imino carboxylic acid ligand i.e. 2-{4-hydroxy-3-[(2-hydroxyphenylimino)methyl]phenylazo}benzoic acid in presence of triethylamine. The complexes were characterized by elemental analysis, IR and multinuclear NMR (1H, 13C and 119Sn) spectroscopy. The structure of 1 in solid state has been determined by X-ray crystallography. Crystal structure of 1 reveals that the compound crystallizes in monoclinic space group P21/c and is a dimeric dimethyltin(IV) complex appended with free carboxylic acid groups. In the structure of 1, the Sn(IV) atoms are hexacoordinated and have a distorted octahedral coordination geometry in which two phenoxy oxygen atoms and the azomethine nitrogen atom of the ligand coordinate to each tin atom. One of the phenoxy oxygen atom bridges the two tin centers resulting in a planar Sn2O2 core. Topological analysis is used for the description of molecular packing in 1. Tin NMR spectroscopy study indicates that the complexes have five coordinate geometry around tin atom in solution state. Since the complexes have free carboxylic acids, these compounds could be further used as potential metallo-ligands for the synthesis of other complexes. The synthesized diorganotin(IV) complexes were also screened for their antimicrobial activities and compound 2 showed effective antimicrobial activities.