Assembly of Di-, Tetra- and Hexanuclear Organostannoxanes Using Hemi Labile Intramolecular N→Sn Coordination: Synthesis, Structure, DFT and Antibacterial Studies

Di-, Tetra- and Hexanuclear Organostanoxanes were obtained from the organotin precursors such as (RSnCl3; R = 2-phenylazophenyl) and diorganotin precursor (R2SnCl2; R = 2-phenylazophenyl) having intramolecular N -> Sn coordination. RSnCl3 on complete hydrolysis followed by reaction with benzoic acid in different stoichiometry in refluxing dry toluene afforded a hexanuclear [RSn(mu 2-O)(mu 2-O2CPh]6 center dot 4PhCH3 (1) and a dinuclear [(RSn)2(mu 2O)(mu 2-O2CPh)2(kappa 2-O2CPh)2]center dot PhCH3 (2) monoorganostannoxane clusters. While diorganotin precursor (R2SnCl2; R = 2-phenylazophenyl) on complete hydrolysis in the presence of NaOH afforded a tetranuclear diorganostannoxane macrocycle [R2Sn(mu 2-O)]4 (3). Single crystal x-ray diffraction analyses revealed that all the three complexes consist Sn centers in different coordination environment acquiring distorted octahedral, distorted pentagonal bipyramidal and distorted trigonal bipyramidal geometry respectively. Complexes 1-3 are further studied for their antibacterial activity which revealed complex 3 shows better antibacterial activity compared to the other complexes. From the DFT studies, we have found that the order of biological activity and HOMO-LUMO gap for these complexes are in similar order (3 > 1 > 2) which suggests that the biological activity and HOMO-LUMO gap are well correlated with each other for these complexes.