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.

Automated summary

Three organostanoxanes with different nuclearities were synthesized using different organotin precursors, showing hexanuclear, dinuclear, and tetranuclear structures. The antibacterial activity and HOMO-LUMO gap of these complexes are correlated, with complex 3 exhibiting better antibacterial activity.