The study was focused on the structure-activity relationship of some newly synthesized hexacoordinated dimethyltin(IV) complexes of fluorinated β-diketone/β-diketones and sterically congested heterocyclic β-diketones. These complexes were screened for their antibacterial activity against a Gram-negative bacterium (Pseudomonas aeruginosa) and Gram-positive bacteria (Streptomyces griseus, Staphylococcus aureus, Bacillus subtilis) and the results were compared with those of a standard antibacterial drug. Some of the complexes were also screened for their antifungal activity against various fungi (Aspergillus niger, A. flavus, Trichoderma viride, Fusarium oxysporum) and were found to be active. These new hexacoordinated complexes of dimethyltin (IV) were generated by reactions of dimethyltin(IV) dichloride and sodium salts of fluorinated β-diketone/β-diketones and sterically congested heterocyclic β-diketones in 1:1:1 molar ratio in refluxing dry benzene. Plausible structures of these complexes were suggested with the aid of physicochemical and spectroscopic studies. 119 Sn NMR spectral data revealed the presence of a hexacoordinated tin centre in these dimethyltin(IV) complexes.

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A comprehensive density functional theory (DFT/B3LYP method) investigation was done to study the generation, optimized topologies, bonding, reactivity, stability, distortions and enhancement of antimicrobial potential of a number of organic–inorganic hybrid complexes of zirconium (IV). Zirconium (IV) complexes having the general formulae ZrL(Cl)2 and Zr(L)2 were prepared by the reaction of zirconium tetrachloride with dipotassium salts of sterically constrained oximes of heterocyclic β‐diketones in different stoichiometric ratios in refluxing anhydrous THF. Plausible topologies of these complexes were suggested with the aid of physico‐chemical and spectral studies. The optimized topologies of the complexs of the types ZrL(Cl)2 and Zr(L)2 were given by comprehensive DFT investigation. The molecular orbitals, molecular electrostatic potential, chemical reactivity, energy optimization, stability and distortions of these newly generated complexes were studied by DFT. These complexes were screened against bacterial isolate E. Coli and fungal isolates viz. A. Niger and T. Reesei. The chemical reactivity of these complexes is corroborated by small energy gap. Few principal quantum chemical descriptors were correlated with the enhancement of antimicrobial potential of these sterically constrained complexes of zirconium (IV). The presence of ‐CH2CH3, ‐C6H5 and –C6H4Cl (p) groups in complexes of the types ZrL(Cl)2 and Zr(L)2 provides an opportunity to examine the effect on optimized energy, stability and distortions of optimized topologies.

The crystal structure of a tin (II) complex of composition Sn[CH 3 C0C:CON(C 6 H 5 )]^CH 3 ] 2 CH 3 OH has been determined. Crystals are monoclinic, space group P2,/c, M=581.20, a=15.441(l), b=18.503(2), c=9.152(l)Ä, ß=106.50(8), V-2507.1 Ä 3 , Z=4, Dcalc =1.540 g cnr 3 -λ(Μο-Κα) = 0.71069 Α, μ=10.62 cm 1 , T=295K, F(000) = 1176, R=0.073 for 3469 unique reflections. The central tin atom is chelated by two crystallographically equivalent heterocyclic ß-diketone ligands. A distorted trigonalbipyramidal geometry has been assigned to this complex as inferred from X-ray crystal data.