The structure–activity relationship of some hexacoordinated dimethyltin(IV) complexes of fluorinated β-diketone/β-diketones and sterically congested heterocyclic β-diketones Arti Sharma, Asha Jain* and Sanjiv Saxena The study was focused on the structure–activity relationship of some newly synthesized hexacoordinated dimethyltin(IV) com- plexes 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 (Strepto- myces 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 steri- cally 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. Copyright © 2015 John Wiley & Sons, Ltd. Additional supporting information may be found in the online version of this article at the publisher’s web site. Keywords: dimethyltin(IV) dichloride; β-diketones; heterocyclic β-diketones; antibacterial activity; antifungal activity Introduction The structure–activity relationship of organotin(IV) complexes [1–4] is an expanding area of research and has made unprecedented ad- vances. Some organotin(IV) complexes are potentially active biolog- ical agents [5–7] and have great impact in the biosphere. Organotin (IV) complexes are used as fungicides, [8–11] bactericides, [12–17] antioxidants, [18] analgesics [19,20] and insecticides. [21] Diorganotin(IV) complexes attract considerable interest in biological applications owing to their use as antineoplastic agents. [22] Organotin(IV) com- plexes of β-diketones, [23,24] heterocyclic β-diketones, [23,25–31] Schiff bases, [32–35] oximes, [36,37] amino acid derivatives, [24,27,37] sulfa drug derivatives, [38] etc., have been cited in the literature due to their po- tential industrial and biological applications. [31,33–35] 5-Pyrazolone ligands are used as pharmaceutical agents and exhibit anti- inflammatory [39] as well as antioxidant [40] properties. Acylpyra- zolones also demonstrate multidrug resistance modulating activity.. [41] 1,3-Diketones are used as important intermediates in or- ganic synthesis, [42] as pharmaceuticals agents and in the synthesis of other biologically relevant compounds. [43] Recently, it has been re- ported that β-diketones are important pharmacophores for the HIV integrase (1 N) inhibitors. [44] In order to study the structure–activity relationship of some hexacoordinated dimethyltin(IV) complexes, the reactions of dimethyltin(IV) dichloride with sodium salts of fluorinated β- diketone/β-diketones and sterically congested heterocyclic β-diketones were carried out which afforded some new hexacoor- dinated dimethyltin(IV) complexes. It is pertinent to correlate the mo- lecular structures of these complexes with their biological activities. Experimental All chemical reactions were carried out under anhydrous condi- tions. Me 2 SnCl 2 , fluorinated β-diketone, acetylacetone, benzoy- lacetone and dibenzoylmethane are commercially available. Sterically congested heterocyclic β-diketones were prepared using Jensen’s method. [45] Solvents were purified and dried using standard methods. [46] Tin was determined as tin(IV) oxide. [47] Melting points of the hexacoordinated dimethyltin(IV) complexes were determined in sealed capillaries. Molecular weights of the complexes were determined using the Rast method. IR spectra of the complexes were recorded as KBr pellets with a Shimadzu (Japan) 8400S FT-IR spectrophotometer in the range 400–4000 cm À1 . 1 H NMR and 13 C NMR spectra of the complexes were recorded in CDCl 3 solution using tetramethylsilane as an in- ternal standard with a Bruker 400 MHz spectrometer. 119 Sn NMR spectra of representative complexes were recorded with Me 4 Sn as an external reference. C, H, N analyses of the hexacoordinated dimethyltin(IV) complexes were done by the Eager xperience. Mass spectra of the complexes were recorded with a Shimadzu GC-MS QP 2010 ULTRA. * Correspondence to: Asha Jain, Department of Chemistry, University of Rajasthan, Jaipur, India. E-mail: aashajain27@gmail.com Department of Chemistry, University of Rajasthan, Jaipur, India Appl. Organometal. Chem. 2015, 29, 499–508 Copyright © 2015 John Wiley & Sons, Ltd. Full paper Received: 19 February 2015 Revised: 26 March 2015 Accepted: 27 March 2015 Published online in Wiley Online Library: 2 June 2015 (wileyonlinelibrary.com) DOI 10.1002/aoc.3321 499