Integrated Experimental and Theoretical Studies of Organotin(IV)‐Hydrazone Complexes: Synthesis, Structural Elucidation, Computational Insights, and Antimicrobial Activity

In the search of some new therapeutic agents against microbial infections, a series of pentacoordinated diorganotin(IV) complexes [R₂SnL^1-2] were prepared by reacting 2-(4-chloro-2-methylphenoxy)acetohydrazide and 3-ethoxy/5-nitrosalicylaldehyde with R₂SnCl₂ (R = Me, n-Bu, Et, Ph). Various spectral techniques, including NMR (¹H, ¹³C, ¹¹⁹Sn), FT-IR, and HRMS, confirmed their pentacoordinated geometry of complexes, further validated by single-crystal x-ray diffraction (SC-XRD) analysis of complex 3 [Me₂SnL¹] that displays monoclinic crystal system with a deformed square-pyramidal geometry around the tin metal center, with two methyl groups, N_azomethine, O_phenolic, and O_enolic atoms. Furthermore, the antimicrobial study shows that all synthesized compounds (1-10) exhibit significant activity against microbial infections. Among them, complexes 6 and 10 demonstrated the highest efficacy. Findings confirmed that the biological activity of complexes surpasses that of ligands (1, 2) itself, with complex 6 [Ph₂SnL¹] demonstrating highest efficiency in controlling microbial infections with minimum inhibitory concentration (MIC) values of 0.0049 µmol/mL against Candida albicans and Escherichia coli and comparable to standard drugs such as ciprofloxacin and fluconazole. To validate the enhanced antimalarial potential of the ligand 1 and its complexes (3-6), density functional theory (DFT) calculations were performed on all synthesized compounds.