Structure–activity studies on the fungitoxicity of some triorganotin(IV) compounds

Seventeen triorganotin(IV) compounds, with the general formula R₃SnX, containing symmetrical and unsymmetrical combinations of alkyl and aryl groups on tin and with a wide variation in the non-carbon-bonded anionic (X) residues, were examined along with three formally pentacoordinated adducts of triaryltin chlorides with triphenylphosphine oxide for their antifungal activity against nine plant pathogenic and saprophytic fungi. The in vitro tests included inhibitory studies on radial growth, mycelial growth, spore germination, and germ tube elongation. A significant finding was the dependence of fungitoxicity on the nature of the X group in both the tributyltin and triaryltin series, in contrast to earlier published reports on the negligible influence of the X groups on overall toxicity relative to the R group. This suggests that the X group is significantly involved in transporting the biocide to the reactive sites, and that the X group which tends to confer increased solubility to the triorganotin compound gives rise to increased activity. In studies of R group variations, tri-iso-butyltin bromide was found to be much less fungitoxic than tri-n-butyltin compounds, a result which is reconcilable in terms of increased steric encumbrance at the tin site in the former case. The steric factor is also implicated in the reduced activities observed for tris(p-tolyl)tin and tris(p-chlorophenyl)tin compounds relative to (Ph₃SnX) towards most of the fungi screened in this study. In general, it was also noted that the triaryltins were more selective in their antifungal action than the trialkyltins, which exhibited broad spectral activity when applied at the concentration level of 10 μg cm^?3.     

Effect of six triorganotin(IV) compounds on nitrification and ammonification in soil

The effects of six triorganotin(IV) compounds and of Thiram on nitrification and ammonification in soil were investigated. Low concentrations of up to 50 μg g^?1 of the triorganotin(IV) compounds enhanced nitrate-nitrogen (NO₃^?-N) production in soil. Except for diphenylbutyltin bromide, which inhibited nitrification at 250 μg g^?1, the other triorganotin(IV) compounds were inhibitory at concentrations of 100 μg g^?1 to less than 250 μg g^?1. At 10 μg g^?1, only triphenyltin acetate was less inhibitory towards nitrification compared with Thiram. At 250 μg g^?1, Thiram exerted a strongly persistent inhibitory effect towards nitrification. The NO₃^?-N level recorded 28 days after application was only 0.10 μg g^?1 soil. With the triorganotin compounds NO₃^?-N levels of 7.05–12.06 μg g^?1 soil were recorded 28 days following their application. The deleterious effects of the triorganotin(IV) compounds were less persistent and recovery of nitrification was evident seven days after application. Low concentrations of Thiram and triorganotin(IV) compounds inhibited ammonification, whereas higher concentrations enhanced ammonification. Complete inhibition of ammonification was attained 21–28 days after application of Thiram at 50 μg g^?1. On the other hand, with the triorganotin(IV) compounds, except for diphenylbutyltin bromide at 10–50 μg g^?1, ammonification persisted at all concentrations 28 days after application.     

Persistence of fungitoxicity of two triorganotin(IV) compounds in soil

The persistence of triphenyltin chloride-triphenylphosphine oxide (Ph₃SnCl·Ph₃PO) and diphenylbutyltin bromide (Ph₂BuSnBr) in unsterilized sandy loam soil maintained in the dark at 60% of its water-holding capacity and at 27±2°C was studied over a period of 29 days. The percentage recovery of the compounds upon extraction with acetone immediately after application to soil was 60% for Ph₃SnCl·Ph₃PO and 9.8% for Ph₂BuSnBr. The half-lives of the compounds were 15 days for Ph₃SnCl·Ph₃PO and 14.2 days for Ph₂BuSnBr. After 29 days following application of the compounds in soil < 8.3 μg g^?1 of Ph₃SnCl·Ph₃PO and < 5.1 μg g^?1 of Ph₂BuSnBr remained in soil compared with the starting concentration of 50 μg of each compound per gram soil. The two triorganotin compounds were evidently easily degraded and the compounds may be applied every 2–3 weeks in the field at a rate of at least 0.005–0.01 kg ha^?1.     

Changes in fungal and bacterial populations in soil treated with two triorganotin(IV) compounds

The effects of two triorganotin(IV) compounds, diphenylbutyltin bromide (Ph₂BuSnBr) and triphenyltin chloride·triphenylphosphine oxide (Ph₃SnCl·Ph₃PO), on soil bacterial and fungal populations were compared with that of Thiram and the commercial triorganotin fungicide ‘Brestan’ (triphenyltin acetate, Ph₃SnOAc). Soil fungal populations were reduced most by Thiram, then by Ph₃SnCl·Ph₃PO, Ph₂BuSnBr and Ph₃SnOAc, in that order. Following the application of the compounds, there was a marked increase in the bacterial population in soil, the increase being greatest with Thiram and least with Ph₃SnCl·Ph₃PO. The triorganotin(IV) compounds were less harmful to soil fungi than Thiram. In Thiram-treated soil, recolonization was slower than in soil treated with the triorganotin(IV) compounds. More species of fungi were tolerant to and persisted after application of the triorganotin(IV) compounds compared with Thiram. Among the fungi that were tolerant to the triorganotin(IV) compounds were cellulolytic species such as Trichoderma.     

Biocidal organotin compounds: Part 1. Preparation and characterization of triorganotin(IV) 4-pyridyl- and 2-pyrimidyl- thioacetates and the crystal structure of triphenyltin(2-pyrimidylthioacetate)

The preparation and spectroscopic characterization of [R₃Sn(O₂CCH₂SC₅H₄N-4)], R == Ph, benzyl (Bz), cyclohexyl (c-Hex) and n-Bu, and of [R₃Sn(O₂CCH₂SC₄H₃N₂-2,6)], R == Me, Ph and n-Bu, are reported. The 2-pyrimidyl compounds feature trigonal bipyramidal tin centres with trans-R₃SnO₂ geometries as was confirmed by X-ray crystallography for [Ph₃Sn(O₂CCH₂SC₄H₃N₂-2,6)]. ¶ By contrast the 4-pyridyl compounds have trigonal bipyramidal geometries in the solid state (arising from intermolecular Sn…N interaction) and tetrahedral geometries in solution. The biocidal activity of these compounds against the fungi Helminthosporium maydis (ITCC 2675) and H. oryzae (ITCC 2675), both of which damage crops such as maize and rice, shows promise. Encouraging is the observation that the compounds show no adverse phytotoxicity at concentrations to 10^?3M.     

Labdanes: antifungal compounds isolates from the resinous exudate of Madia sativa against Phytophthora cinnamomi Rands

Abstract

In this study, resinous exudate from Madia sativa was analyzed by GC-MS. The major bioactive compounds 13,14,15-trihydroxylabd-7-ene (14) and 3,14,15-trihydroxylabd-8-ene (15) were isolated and their structures were determined by NMR. The antifungal activity of the resinous exudate and the labdanes compounds was evaluated using the inhibitory effects on the mycelial growth of plant pathogen Phytophthora cinnamomi causing root rot of various crops. The evaluation of the resinous exudate showed no inhibition over 50% at 75?mg/L, while compound 15 had the stronger effect on the myceliar growth of P. cinnamomi, with a 94.6% inhibition at 175?mg/L. The same way, the mixture of both compounds in equal parts did not show a synergistic effect but showed similar percentages of mycelial growth inhibition from 25?mg/L with respect to the compounds separately.     

Diorganotin(IV) and triorganotin(IV) derivatives of diphenic acid

The diorganotin(IV) and triorganotin(IV) derivatives R₂SnA (R = Me, n-Pr, n-Bu, n-Oct) and (R₃Sn)₂A [R = Me, Ph, cyclohexyl (Cyh); A = an anion of diphenic acid] have been prepared and characterized by elemental analysis, IR, ¹H and ¹³C NMR spectroscopies. Tetrahedral tin forms a part of a diphenate cyclic ring in the diorganotin complexes with unidentate carboxylates, which have further been used for the synthesis of cyclic acid anhydrides. The soluble dinuclear triorganotin complexes (Me, Ph) possess symmetrically bonded carboxylates while the less soluble compound (Cyh₃Sn)₂A has two asymmetrically bonded carboxylates. All have a trigonal bipyramidal structure with R₃Sn units remote from each other.     

Insecticidal effects of organotin(IV) compounds on Plutella xylostella (Linnaeus) larvae I: Topical application toxicity and antifeedant effect

Structure–activity relationship studies were conducted with early fourth-instar larvae of a highly resistant strain of the diamondback moth, Plutella xylostella (Linnaeus) on (1) toxicity by topical appliction of 43 organotin compounds, and (2) the antifeedant effect of a selected number (17) of these compounds on treated Brassica chinensis (Chinese cabbage) leaves. The toxicity data revealed that the triorganotins (R₃SnX) were, without exception, more toxic than the commercial sample of malathion (84% active ingredient) used in the tests. Among the diorganotins, phenylcyclopentyltin oxide proved to be as active as malathion. Within the triorganotin series, the tricyclohexyltins were generally more toxic than the triphenyltins, the most active tricyclohexyltin compound being (c-C₆H₁₁)₃Sn(2-pyridinethiolato N-oxide) (LC₅₀ 0.03 μg μl^?1), which was almost 500-fold more active than malathion. The most active compound in the triphenyltin class was O, S-bis(triphenyltin)mercaptoacetate (LC₅₀ 0.30 μg μl^?1). Variations in the anionic X group resulted only in marginal changes in activity in the (c-C₆H₁₁)₃Sn series, but significant changes in activity were obtained with the Ph₃Sn compounds, especially the ring-substituted phenoxyacetates, (4-ZC₆H₄)OCH₂(O)COSnPh₃. In the mixed triorganotin compounds an increase in activity was observed when one of the phenyl groups in Ph₃SnOH was replaced by the p-chlorophenyl group. In the antifeedant tests, the tricyclohexyltins were found to be generally more effective than the triphenyltins. In most cases, antifeedant activity paralleled the toxicity by topical application trends in the (c-C₆H₁₁)₃Sn series, but in the Ph₃Sn series an inverse trend was observed. The diorganotin compound (c-C₅H₉)PhSnO exerted a relatively pronounced antifeedant activity which was comparable with that of a number of triphenyltin derivatives. It was established from histological studies of the mid-gut cross-sections of the treated larvae that, in most cases, the organotins affected the columnar cells physiologically; an exception was noted for Ph₃SnOC(O)C₆H₄COOH-4 which, like malathion, caused severe morphological damage to the cell membrane.     

Polar compounds isolated from the leaves of Albertisia delagoensis (Menispermaceae)

Aqueous infusions of the leaves of the shrub Albertisia delagoensis (Menispermaceae) are used in South Africa in traditional Zulu medicine to alleviate a variety of symptoms, including fever, and intestinal problems. We report the analysis of such an aqueous extract using the HPLC-NMR technique. A number of polar compounds were identified, including proto-quercitol, nicotinic acid, allantoic acid, 3,4-dihydroxy-benzoic acid, phthalic acid and the aporphine alkaloid derivative roemrefidine. Allantoic acid and roemrefidine have been fully characterised by (1)H- and (13)C-NMR and mass spectrometry. Earlier reports of antiplasmodial activity of roemrefidine and of A. delagoensis extracts are correlated with this study and with the antipyretic properties of neutral aqueous extracts.     

Synthesis,structural and biocidal activity studies of triorganotin(IV) compounds of some N-protected amino-acids

Seven new triorganotin(IV) complexes of the type R₃SnL (L=N-phthaloyl derivatives of glycine, DL-alanine or N-acetyl- and N-benzoyl-glycine and -cysteine; R-n-C₄H₉ or C₆H₅) have been prepared by reacting the sodium salt of the ligand and the triorganotin(IV) chloride in 1:1 molar ratio in methanol. The complexes have been characterized by elemental analysis, molecular mass determination, IR and ¹H NMR spectroscopy. The complexes are monomeric in molten camphor and are moderateely soluble in the common organic solvents. The spectral data support cis five-coordinate complexes with an unsymmetrical bidentate coordination of the carboxylate group to tin. The complexes exhibit some insecticidal effect on Bean Weevils (Sitophilus granaria) even at low concentration and they also show fungicidal activity on Aspergillus niger and Helminthosporium taulosum. Some of the complexes are found to be more effective than tri-n-butyltin and triphenyltin chlorides.     

Quality variation and standardization of black pepper (Piper nigrum): A comparative geographical evaluation based on instrumental and metabolomics analysis

Black pepper (Piper nigrum; BP), known as the ‘king of spices’, imported from various countries is widely available in Saudi Arabian markets, as its demand as a food as well as a medicine for minor ailments is increasing in the country. However, there is a lack of appropriate information regarding these samples in terms of quality variation and standardization. We thus aimed to evaluate the quality and standardize the BP sample with respect to its physicochemical characters, active principle variation [i.e. piperine (PPN)], toxicity, and biological activity. The main focus is to validate whether any difference exists in the quality and quantity of active principle in these samples. For this purpose, physicochemical (chemical tests and ash values) and instrumental analyses [accelerated solvent extraction (ASE), ultra-high-pressure liquid chromatography (UHPLC)-diode array detector, infrared (IR), nuclear magnetic resonance (NMR), and inductively coupled plasma-MS (ICP-MS)] and biological evaluation {in vitro antioxidant activity [2,2-diphenyl-1-picrylhydrazyl and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)] and cytotoxicity assay} were performed. An extract yield (g) with %recovery of 2.26 ± 4.24 (11.3) was obtained for the Vietnamese sample, using a fast and rapid method of extraction (ASE). These values were 1.22 ± 2.64 (6.1) and 0.75 ± 1.69 (3.75) for the Pakistani and Indian samples. Physicochemical tests revealed the presence of flavonoids and phenolic compounds in all samples; however, in the Vietnamese sample a low amount of total, acid-insoluble, and high water-soluble ash value was noted. IR and NMR was applied to further standardize the samples. Results of ICP-MS analysis showed a high amount of macronutrients and micronutrients in the samples tested while UHPLC analysis revealed a high amount of PPN (ng/mL) in the Pakistani sample (1,362,614.09); these values were 1,051,848.04 and 768,512.81 for the Vietnamese and Indian samples, respectively. In vitro antioxidant and cytotoxicity activities revealed higher potential for the Vietnamese sample. The samples were properly standardized and effectively differentiated in terms of quality and biological activities using a fast and reliable method, however it certainly does not mean that a particular geographical region is more better or productive in terms of herbal products.     

Studies on the phytotoxic effects of some organotin(IV) compounds on the germination of the mung bean seed,Phaseolus aureus

A selected range of organotin(IV) compounds of formula R_xSnX_4-x (x = 2 or 3; R = alkyl, cycloalkyl or aryl), as well as the adducts, (p-ZC₆H₄)₃SnCl. Ph₃PO (Z = H, Me) were examined in vivo for their phytotoxic effects relative to the more powerful s-triazine herbicides against the mung bean seed, Phaseolus aureus. Phytotoxicity was assessed in terms of changes in (a) weights of primary leaves, (b) weights of cotyledons, (c) seedling heights and (d) root morphology. The triorganotin compounds were more phytotoxic than the diorganotins, and within the R₃Sn structural class, inhibitory potency was greater for alkyltins than for aryltins. Decreasing the alkyl chain lengths or placing electrondonating substituents on the aromatic rings increased the phytotoxicity. A significant phytotoxic effect, comparable with that of Ph₃SnCl, was manifested by tricyclohexyltin chloride, in marked contrast to the well-known low phytotoxicity of tricyclohexyltin hydroxide. Using Ph₃SnCl as the model compound, it was further demonstrated that the total chlorophyll content decreased with increasing concentration of Ph₃SnCl, but the ration of chlorophyll a to chlorophyll b was constant. It was also found that tin uptake in the seedlings was directly proportional to Ph₃SnCl test concentrations; the magnesium and iron levels in the treated seedlings, however, were unchanged relative to the control.     

Synthesis and structural elucidation of bioactive triorganotin(IV) derivatives of sodium deoxycholate

Trimethyl (1), tributyl (2), and triphenyl tin (3) derivatives of sodium (R)-4-((3R,5R,8R,9S,10S,12S,13R,14S,17R)-3,12-dihydroxy-10,13-dimethyl-hexadecahydro-1H-cyclopenta[a]phenanthren-17-yl)pentanoate (sodium deoxycholate) were synthesized by refluxing sodium deoxycholate with the corresponding triorganotin(IV) chloride in 1?:?1?M ratio. All the three compounds were characterized by elemental analysis, infrared spectroscopy, ¹H, ¹³C, ¹¹⁹Sn NMR, and X-ray diffraction studies. From FT-IR spectra, Δν values proposed bridging or chelating behavior of the ligand. The three compounds gave a trigonal bipyramidal geometry in the solid state and tetrahedral geometry in solution. Single crystal of 1 showed polymeric trigonal bipyramidal geometry. Synthesized compounds obtained were screened for their antimicrobial and antitumor activities against A2780 cell line. Results revealed that only 2 showed significant antibacterial activity. However, all the three compounds exhibited promising antifungal and anticancer activities.     

Biocidal Organotin Compounds. Part 2. Synthesis,Characterization and Biocidal Properties of Triorganotin(IV) Hydantoic Acid Derivatives and the Crystal Structures of Triphenyltin and Tricyclohexyltin Hydantoates

The preparation and spectroscopic (¹H NMR, UV and IR) characterization of three R₃Sn(O₂CCH₂N(H)C(O)NH₂) [R=Ph, c-Hex (cyclohexyl) or n-Bu] compounds are reported. A different mode of coordination is indicated for the hydantoate ligand in the R=Ph compound compared with the R=c-Hex and R=n-Bu compounds, as confirmed by a crystallographic analysis. The structure of [Ph₃Sn(O₂CCH₂N(H)C(O)NH₂)] is polymeric owing to the presence of bridging hydantoate ligands such that each ligand coordinates one tin atom, via one of the carboxylate oxygen atoms, and a symmetry-related tin atom via the carbonyl group at the other end of the molecule. The structure features distorted trigonal-bipyramidal tin atom geometries with a trans -R₃SnO₂ motif. The structure of [c-Hex₃Sn(O₂CCH₂N(H)- C(O)NH₂)], by contrast, is monomeric, distorted tetrahedral, as the carboxylate group is monodentate and there are no additional tin–ligand interactions. The structures are each stabilized by a number of intermolecular hydrogen bonds. Fungitoxicity and phytotoxicity studies indicate that the R=n-Bu derivative is the more active compound.     

Structural characterization of triorganotin(IV) complexes with sodium fusidate and DFT calculations

Three new complexes of the steroid sodium fusidate (sodium 2-[(1S,2S,5R,6S,7S,10S,11S,13S, 14Z,15R,17R)-13-(acetyloxy)-5,17-dihydroxy-2,6,10,11-tetramethyl tetracyclo[8.7.0.0^2,7.0^11,15] heptadecan-14-ylidene]-6-methylhept-5-enoate = (NaFusidate, NaFA)]), with triorganotin(IV) moieties have been prepared and investigated by conventional techniques as FTIR, Mössbauer, ESI-MS and NMR spectroscopy. The isolated compounds showed stoichiometries organotin(IV)/fusidate 1/1, R₃Sn(IV)FA (R = Me, FA1; Bu, FA2; Ph, FA3). The ligand coordination sites were determined by FTIR spectroscopic measurements. In the complexes, the carboxylate group of the fusidate ligand behaves as monodentate monoanionic donor, binding the Sn(IV) through one oxygen atom.On the basis of C-Sn-O_COO angles, calculated through the rationalization of the ¹¹⁹Sn Mössbauer parameter nuclear quadrupole splitting, it has been confirmed that, in all the solid state complexes, the Sn(IV) was tetracoordinated in a distorted tetrahedral structure.Further data from ¹¹⁹Sn CP-MAS spectra confirmed the distorted tetrahedral arrangement.In MeOH solution, ¹H, ¹³C and ¹¹⁹Sn NMR spectroscopy showed monomeric complexes, where the carboxylate group mainly acts as monodentate ester-type ligand, and the occurrence of a coordinated solvent molecule to the tin center, as validated by non-relativistic NMR DFT study.     

Structural study of di- and triorganotin(IV) dicarboxylates containing one double bond

Tri- and diorganotin(IV) dicarboxylates derived from trans-glutaconic acid and acetone 1,3-dicarboxylic acid were prepared. Their structure was studied using NMR, IR, and MS data. All of these compounds (except for compound 2a) are polymeric in the solid state and depolymerise upon dissolving in deuteriochloroform to give monomeric particles with four-coordinated central tin atoms. X-ray crystallography was used to characterize (E)-bis(tributylstannyl) pent-2-enedioate (1a). This compound crystallizes in a monoclinic space group system. The supramolecular organization of 1a can be described as layered polymeric sheets constructed of forty-membered rings that are interconnected on four different sites to the third dimension. Each layer assembled of the forty-membered rings, is made up of six triorganotin fragments and six trans-glutaconic acids, where four of them are incorporated in the core of the ring and other two are bidentate bridging and participating in the ring system by three atoms of CO₂ group only.     

Self-assembly of triorganotin(IV) or diorganotin(IV) moieties and 2-methylpyrazine-5-acid: Syntheses, characterizations and crystal structures of monomeric, polymeric or tetranuclear macrocyclic compounds

A series of diorganotin(IV) and triorganotin(IV) compounds of the type [R₂Sn(pca)₂ClSnR₃]₂ (RPhCH₂1, 2-ClC₆H₄CH₂2, 2-FC₆H₄CH₂3, 4-FC₆H₄CH₂4, 4-CNC₆H₄CH₂5, 4-ClC₆H₄CH₂6, 2,4-Cl₂C₆H₃CH₂7; Hpca2-methylpyrazine-5-acid), [(ⁿBu)₃Sn(pca)]_∞8, [(CH₃)₂Cl₂Sn(pca)Sn(CH₃)₂(pca)]_∞9, {[(ⁿBu)₂Sn(pca)]₂O}₂10 and {[Ph₂Sn(pca)]₃O₂[Ph₂Sn(OCH₃)]} 11 have been obtained by reactions of 2-methylpyrazine-5-acid with triorganotin(IV) chloride, diorganotin(IV) dichloride, and diorganotin(IV) oxide. All compounds were characterized by elemental, IR, and NMR spectra analyses. The crystal structure of compounds 1, 8-11 were determined by X-ray single crystal diffraction, which revealed that compound 1 was tetranuclear macrocyclic structures with seven-coordinate and five-coordinate tin atoms, compounds 8 and 9 were polymeric chain structures with five-coordinate and seven-coordinate tin atoms, compounds 10 and 11 were monomeric structures with six-coordinate and five-coordinate tin atoms.     

Synthesis,characterization, and antibacterial activity of triorganotin(IV) complexes of 2-methylphenol

The triorganotin(IV) complex Ph₃Sn(OPhMe-2) (1) has been synthesized by the reaction of Ph₃SnCl with NaOPhMe-2, while complexes of composition n-Bu₃Sn(OPhMe-2) (2) and Me₃Sn(OPhMe-2) (3) (where ?OPhMe-2 = ?OC₆H₄CH₃-2) have been obtained from the reaction of n-Bu₃SnCl and Me₃SnCl with 2-methylphenol in the presence of triethylamine in carbon tetrachloride. The complexes have been characterized by elemental analyses, molar conductance measurements, molecular weight determination, and IR, ¹H NMR, ¹³C NMR, and mass spectral studies. Thermal behavior of the complexes has been studied by TG and DTA techniques. The organotin(IV) complexes have also been screened for antibacterial activity and exhibit appreciable activity. The reactions of the complexes with 3- and 4-cyanopyridines yielded 1 : 1 adducts authenticated by physicochemical and IR and ¹H NMR spectral data.     

Syntheses,characterizations and crystal structures of monomeric or macrocyclic compounds of di- or triorganotin (IV) moieties with 4,4′-thiodibenzenethiol

Six organotin compounds with 4,4′-thiodibenzenethiol (LH₂) of the type R_nSnL_4−nSnR_n (n = 3: R = Me 1, Ph 2, PhCH₂3, n = 2: R = Me 4, Ph 5, PhCH₂6) have been synthesized. All compounds were characterized by elemental analysis, IR and NMR (¹H, ¹³C, and ¹¹⁹Sn) spectra. The structures of compounds 1, 2, 4, 5 and 6 were also determined by X-ray diffraction analysis, which revealed that compounds 1 and 2 were monomeric structures, compounds 4, 5 and 6 were centrosymmetric dinuclear macrocyclic structures, and all the tin(IV) atoms are four-coordinated. Furthermore, supramolecular structures were also found in compounds 1, 2, 4, 5 and 6, which exhibit one-dimensional chains, two-dimensional networks or three-dimensional structures through intermolecular C–H?S weak hydrogen bonds (WHBs), non-bonded Sn?S interactions or C–H?π interactions.     

Synthesis,characterization and antimicrobial activities of triorganotin(IV) complexes with azo-azomethine carboxylate ligands: crystal structure of a tributyltin(IV) and a trimethyltin(IV) complex

Triorganotin(IV) complexes with polyaromatic azo-azomethine carboxylate ligands viz. 2-{4-hydroxy-3-[(2/4-hydroxyphenylimino)methyl]phenylazo}benzoic acids [H₃L¹/H₃L²] were synthesized by reacting the ligands with either bis-tri-n-butyltin(IV) oxide (for 1 and 4) or trimethyltin(IV) chloride in presence of triethylamine (for 2 and 5) or triphenyltin(IV) hydroxide (for 3 and 6). The complexes were characterized by elemental analysis, UV, IR, NMR, and mass spectrometry. NMR spectroscopic studies of the compounds suggested that the complexes adopt four-coordinate tetrahedral geometry around tin in solution. Molecular structures of 1 and 2 were determined by single-crystal X-ray diffraction. Both complexes have distorted trigonal bipyramidal geometry around tin in the solid state. Compound 1 is a one-dimensional (1-D) double chain coordination polymer which can be described as two different 24- and 30-membered non-porous macrocyclic rings constructed from two tributyltin units and two ligand moieties. The structure of 2 comprises a discrete cyclic centrosymmetric dimer with two lattice water molecules per formula unit. In the dimer, two trimethyltin entities are bridged by two ligand moieties. The dimers are further interconnected with lattice water molecules by multiple O–H?O hydrogen bonds to form a 1-D H-bonded network. The complexes were also screened for their antimicrobial activities.