Structural and antimicrobial studies of potassium hydrotris(2-mercaptobenzathiazolyl)borate and its organotin(IV) derivatives

Potassium hydrotris(2-mercaptobenzathiazolyl)borate (KL) was formed by the solid state reaction of potassium borohydride and 2-mercaptobenzathiazoline. This ligand was reacted with R _n SnCl_4?n (R =?methyl, butyl and phenyl, n =?2 and 3) in dichloromethane and four different neutral organotin(IV) complexes were obtained. All compounds were characterized by elemental analyses, FT-IR and multinuclear NMR (¹H, ¹³C, ¹¹ B and ¹¹⁹Sn) spectroscopy. Spectroscopic data indicate the six-coordinated nature of tin in its di and triorganotin(IV) complexes.

To check the toxic potential of the ligand and its organotin(IV) complexes, selected bacterial (E. coli, S. epidemidis and S. dysenteriae) and fungal (A. niger, C. albicanes and A. flaves) species were screened. The results were compared with standard drugs kinamycine and miconazole for bacterial and fungal activity, respectively. The toxicity of the organotin(IV) complexes depends on the number and nature of organic groups attached to the tin atom; triorganotin(IV) complexes exhibit better inhibition than diorganotin(IV) complexes. All compounds were also screened on the cyanobacterial strains (Aulosira fertillissma, Anabaena variabilis, Anabaena species and Nostoc muscorum). Results show that the compounds inhibit the growth of organisms at very low concentration.     

Synthesis, structural elucidation and biological activities of organotin(IV) derivatives of (E)-3-(4-methoxyphenyl)-2-(4-chlorophenyl)-2-propenoic acid

A new series of di- and tri-organotin(IV) compounds with the general formula R_4?n SnL _n , where R?=?Me (1,2), Et (3), n-Bu (4,5), n-Oct (6), Ph (7) and L?=?(E)-3-(4-methoxyphenyl)-2-(4-chlorophenyl)-2-propenoate, were synthesized by reaction of silver salt of ligand or ligand acid with diorganotin dichloride/oxide and triorganotin chloride in 2:1 and 1:1 molar ratio, respectively. These compounds were characterized by elemental analyses, FT-IR, multinuclear (¹H, ¹³C, ¹¹⁹Sn) NMR and mass spectrometry. The spectroscopic results revealed that all the diorganotin(IV) compounds possess trigonal bipyramidal structures in solution and octahedral geometry in the solid state around the tin atom. A linear polymeric trigonal bipyramidal structure in the solid state and a tetrahedral environment around the tin atom in non-coordinating solvents has been proposed for the triorganotin(IV) compounds. All synthesized compounds were tested in vitro against a number of microorganisms to assess their biocidal activity. These studies revealed that ligand acid and some of its organotin compounds show promising activity against different strains of bacteria and fungi but lowered than reference drugs.     

Synthesis,spectroscopic characterization,and biological screening of levofloxacin based organotin(IV) derivatives

Four new organotin (IV) complexes with general formula R₃SnL/R₂SnL₂, where R = CH₃, n-C₄H₉, C₆H₅ and L = Levofloxacin, were synthesized and characterized by elemental analyses, FT-IR and NMR (¹H and ¹³C) spectroscopy. Spectroscopic data suggested a six-coordinated geometry for diorganotin(IV) derivatives and a five-coordinated geometry for triorganotin(IV) derivatives. The value of Me–Sn–Me bond angle for di- and trimethyltin complexes using the Lockhart equation, were 150° and 116°, respectively, that corresponded to six and five-coordinate geometry, accordingly. The ligand and its complexes were screened for their antibacterial, antifungal, cytotoxic, and free radical scavenging (DPPH) antioxidant activities. The biological data indicated those as potentially bioactive in each field of the study. Accumulated data of DNA interaction with the synthesized complexes based on UV-Vis, cyclic voltammetry and viscometry suggested an intercalative mode of the interaction.     

Synthesis,Spectroscopy, Semi‐empirical and Biological Activities of Organotin(IV) Complexes with o‐Isopropyl Carbonodithioic Acid

New organotin(IV) complexes have been synthesized by treating potassium o‐isopropyl carbonodithioate with R₂SnCl₂/R₃SnCl in 1 : 2/1 : 1 M/L ratio. All complexes have been characterized by IR and NMR (¹H, ¹³C) spectroscopy. IR results shows that ligand acts as bidentate which is also confirmed by semi‐empirical study. NMR data reveals four coordinated geometry in solution. Computed positive heat of formation shows that complex 5 is thermodynamically unstable. UV/visible spectroscopy was used to assess the mode of interaction and binding of the complexes with DNA which shows that complex 5 exhibits higher binding constant as compared to complex 3 . In protein kinase inhibition assay, compound 3 was found most active, while other biological activities shows that triorganotin(IV) complexes are biologically more active as compared to diorganotin(IV) complexes.     

Biological aspects of new organotin(IV) compounds of 3-maleimidopropionic acid

Four new compounds of organic mono carboxylic acid, 3-maleimidopropionic acid; with Bu₂Sn(IV)²⁺, Ph₃Sn(IV)⁺ and Cychex₃Sn(IV)⁺ having ligand to metal ratio 1:2 and 1:1 were prepared. The spectrophotometric techniques used for structure determination like ¹H-, ¹³C- and ¹¹⁹Sn-NMR, FT IR and ^119mSn Mössbauer have demonstrated that the organotin(IV) moieties establish chemical bonding with the ligand through carboxylic oxygen atom. The percent CHN analyses and MS data also corroborates the spectroscopic results. During in vitro LD₅₀, anti-fungal, anti-bacterial and anti-yeast bioassays promising results were exhibited. In vitro anti-tumour activity assays against five human tumor cell lines, MCF-7 Breast cancer-EVSA-T Breast cancer-WiDr Colon cancer-IGROV Ovarian cancer-M226 Non small cell lung cancer and anti-inflammatory screenings furnished the significant toxicities of the title complexes. In addition the triorganotin(IV) complexes were comparatively less toxic than the diorganotin(IV) complexes.     

Organotin(IV) Complexes of 2-[(2′,4′,6′- Trichlorophenylamido)]benzoic Acid: Synthesis,Coordination Chemistry,and Semi-Empirical Study

A new series of organotin(IV) complexes of aniline derivatives, R₂SnL₂ and R₃SnL [where R = Me, n-Bu, n-Oct, and Ph], have been synthesized by the reaction of ligand acid with respective organotin halides in the presence of triethylamine as base or dioctyltin oxide using a Dean–Stark trap for the removal of water under reflux conditions. Experimental details for the preparation and characterization, including elemental analysis, IR, semi-empirical study, multinuclear NMR (¹H, ¹³C, and ¹¹⁹Sn spectra and EI mass spectral studies) of all reported complexes are provided. The IR data indicate that in both di- and triorganotin(IV) carboxylates, the ligand moiety ?COO acts as a bidentate group in the solid state. Multinuclear NMR data show that triorganotin complexes exhibits a four-coordinated geometry, while diorganotin(IV) complexes show a coordination number greater than four, probably five or six, in solution state.

Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.     

Synthesis,characterziation, semi-empirical quantum-mechanical study and biological activity of organotin(IV) complexes with 2-ethylanilinocarbonylpropenoic acid

Seven different organotin(IV) complexes have been synthesized by reacting 2-ethylanilinocarbonylpropenoic acid with R₂SnCl₂/R₃SnCl under reflux conditions. The organotin(IV) complexes along with ligand have been characterized by different techniques including elemental analysis, FT-IR and multinuclear NMR (¹H and ¹³C). IR data show that complexation occurs through -COO site and the ligand is bidentate which is also confirmed by the semi-empirical quantum-mechanical study. ¹H and ¹³C NMR data confirm the tetrahedral geometry of complexes in solution. The complexes as well as the ligand were also checked for various     

Tributyltin(IV) Butyrate: A Novel Epigenetic Modifier with ER Stress- and Apoptosis-Inducing Properties in Colon Cancer Cells

Organotin(IV) compounds are a class of non-platinum metallo-conjugates exhibiting antitumor activity. The effects of different organotin types has been related to several mechanisms, including their ability to modify acetylation protein status and to promote apoptosis. Here, we focus on triorganotin(IV) complexes of butyric acid, a well-known HDAC inhibitor with antitumor properties. The conjugated compounds were synthesized and characterised by FTIR spectroscopy, multi-nuclear (¹H, ¹³C and ¹¹⁹Sn) NMR, and mass spectrometry (ESI-MS). In the triorganotin(IV) complexes, an anionic monodentate butyrate ligand was observed, which coordinated the tin atom on a tetra-coordinated, monomeric environment similar to ester. FTIR and NMR findings confirm this structure both in solid state and solution. The antitumor efficacy of the triorganotin(IV) butyrates was tested in colon cancer cells and, among them, tributyltin(IV) butyrate (BT2) was selected as the most efficacious. BT2 induced G2/M cell cycle arrest, ER stress, and apoptotic cell death. These effects were obtained using low concentrations of BT2 up to 1 μM, whereas butyric acid alone was completely inefficacious, and the parent compound TBT was poorly effective at the same treatment conditions. To assess whether butyrate in the coordinated form maintains its epigenetic effects, histone acetylation was evaluated and a dramatic decrease in acetyl-H3 and -H4 histones was found. In contrast, butyrate alone stimulated histone acetylation at a higher concentration (5 mM). BT2 was also capable of preventing histone acetylation induced by SAHA, another potent HDAC inhibitor, thus suggesting that it may activate HDACs. These results support a potential use of BT2, a novel epigenetic modulator, in colon cancer treatment.     

C,N-chelated organotin(IV) trifluoroacetates. Instability of the mono- and diorganotin(IV) derivatives.

The C,N-chelated tri-, di- and monoorganotin(IV) halides react with equimolar amounts of CF₃COOAg to give corresponding C,N-chelated organotin(IV) trifluoroacetates. The set of prepared tri-, di- and monoorganotin(IV) trifluoroacetates bearing the L^CN ligand (where L^CN is 2-(N,N-dimethylaminomethyl)phenyl-) was structurally characterized by X-ray diffraction analyses, multinuclear NMR and IR spectroscopy. In the case of triorganotin(IV) trifluoroacetates and (L^CN)₂Sn(OC(O)CF₃)₂, no tendency to form hydrolytic products, or instability towards the moisture was observed. L^CNRSn(OC(O)CF₃)₂ (where R is n-Bu or Ph) and L^CNSn(OC(O)CF₃)₃ forms upon crystallization from THF in the air mainly dinuclear complexes in which the two tin atoms are interconnected either by hydroxo-bridges or by an oxo-bridge and/or by a bridging trifluoroacetate(s). In the case of hydrolysis of L^CN(n-Bu)Sn(OC(O)CF₃)₂, a zwitterionic stannate of formula L^CN(n-Bu)Sn(OC(O)CF₃)₂·CF₃COOH was isolated from the mother liquor, too. Products of hydrolysis of L^CN(n-Bu)Sn(OC(O)CF₃)₂ and L^CNSn(OC(O)CF₃)₃, and some other oxygen bridged organotin(IV) compounds containing the same ligand, were tested as possible catalysts of some transesterification reactions as well as in direct dimethyl carbonate (DMC) synthesis from CO₂ and methanol.     

Di- and Tri-organotin(IV) Complexes of N-Acetyltriglycine and N-Benzoyltriglycine: Synthesis and Spectroscopic Characterization

Di- and tri-organotin(IV) derivatives of N -acetyltriglycine and N -benzoyltriglycine (HA) were obtained by refluxing equimolar mixtures of the ligand and the organotin(IV) oxide or hydroxide in methanol or acetone. According to the spectroscopic data, triorganotin(IV) derivatives adopt a trigonal-bipyramidal structure in which the planar R₃Sn^IV unit is bonded by a monodentate carboxylate group and a donor group, presumably the amide CO. The reaction of HA with the appropriate diorganotin(IV) compounds gave both dicarboxylates R₂SnA₂, with six-coordinated tin, and dimeric tetraorganodistannoxanes {[R₂SnA]₂O}₂, in which the tin atoms are essentially five-coordinated.     

New organotin(IV) complexes with l-Arginine, Nα-t-Boc-l-Arginine and l-Alanyl-l-Arginine: Synthesis, structural investigations and cytotoxic activity

Novel diorganotin(IV) derivatives of l-Arginine (HArg), N_α-(tert-Butoxycarbonyl)-l-Arginine (Boc-Arg-OH) and l-Ala-l-Arg (H₂Ala-Arg), H₂NC(NH)NH(CH₂)₃CH(NHR′)CO₂H, where R′ = H in HArg, R′ = C(O)OC(CH₃)₃ in Boc-Arg-OH, R′ = H₂NCH(CH₃)CO in H₂Ala-Arg and triorganotin(IV) derivatives of Boc-Arg-OH have been synthesized and structurally characterized. The complexes were investigated by FT-IR and ¹¹⁹Sn Mössbauer in the solid state and by ¹H, ¹³C, ¹¹⁹Sn and ¹H-¹H COSY NMR spectroscopy, in solution. The spectroscopic characterization leading to the proposed molecular structures was accomplished on the basis of these experiments. l-Arginine appears to behave as a chelating ligand through carboxylate and -NH₂ groups in Me₂Sn(Arg)₂, while in N_α-t-Boc-l-Arginine complex, the N_α-protected amino group being exempted from coordination, only the carboxylate groups are effectors of bonding to the organometallic moieties. FT-IR spectra give a clear indication that guanidino groups in all the complexes are not involved in coordination, since ν(CN-H) frequency of the terminal guanidino group is fairly constant and unshifted relative to the free ligand. The biological activity of organotin(IV)-complexes was also investigated by use of human HT29 colorectal carcinoma cells. The cytotoxic activity of the compounds was determined by the MTT quantitative colorimetric assay, capable of detecting viable cells in comparison with that exerted by cisplatin. A marked cytotoxic activity for nearly all complexes, is evident being higher than that exerted by cisplatin, while no significant improvement of activity was observed for Me₂Sn(Arg)₂ and Me₂Sn(Ala-Arg), which was confirmed by IC₅₀ values. Then, we assessed whether the cytotoxicity induced by organotin(IV) complexes was associated with the induction of apoptosis. Light microscopy analysis, performed to study the morphological changes induced in HT29 cells, confirmed the results obtained with MTT test. No significant morphological alterations were observed in HT29 cells after treatment with Me₂Sn(Ala-Arg) and Me₂Sn(l-Arg)₂. Cells treated with ⁿBu₂Sn(Boc-Arg)₂, ⁿBu₂Sn(Ala-Arg), ⁿBu₃Sn(Boc-Arg) and Me₃Sn(Boc-Arg), appeared rounded, isolated and detached from culture substrate, indicating the commitment to apoptotic cell death.     

Synthesis,spectroscopic characterization,X-ray crystal structure,biological screening and catalytic studies of organotin(IV) carboxylates of 3-(4-cyanophenyl) acrylic acid

A series of six organotin(IV) carboxylates [Me₂SnL₂] (1), [n-Bu₂SnL₂] (2), [n-Oct₂SnL₂] (3), [Me₃SnL] (4), n-Bu₃SnL (5) and [Ph₃SnL] (6), where L = 3-(4-cyanophenyl) acrylic acid have been synthesized and characterized by elemental analysis, FT-IR and NMR (¹H, ¹³C). The complex (4) was also analyzed by single crystal X-ray analysis which showed distorted trigonal bipyramidal geometry with polymeric bridging behavior. The complexes 1–6 were screened for antimicrobial activities and cytotoxicity. The results showed significant activity with few exceptions. The catalytic activity of complexes was assessed in transesterification reaction of Brassica campestris oil (triglycerides) to produce biodiesel (fatty acid methyl esters). The results showed that triorganotin(IV) complexes exhibited good catalytic activity than their di-analogues.     

Preparation and structural studies of organotin(IV) complexes formed with organic carboxylic acids

The complexes of six organic carboxylic acids (containing {O,O} donor atoms) with Bu₂Sn(IV)²⁺ and Ph₃Sn(IV)⁺ with ligand to metal ratios of 1 : 1 and 1 : 2, were prepared by two different methods. The FtIR and Raman spectra clearly demonstrated that the organotin(IV) moieties react with the {O,O} atoms of the ligands. It was found that in most cases the -COO^-group was chelated to the central metal ions, but monodentate coordination was also sometimes observed. Complex formation was accompanied by a rearrangement of the hydrogen-bonding network existing in the ligands. The complexes probably have polymeric structures. Comparison of the experimental Mössbauer D values with those calculated on the basis of the point charge model formalism revealed that the organotin(IV) moiety has a trigonal-bipyramidal (tbp) geometry, and in certain cases a tetrahedral (tetr) geometry too. Finally, the local structure of the maleic acid complex formed with Bu₂Sn(IV)²⁺ was determined by an EXAFS method.     

New mononuclear diorganotin(IV) dithiocarboxylates: synthesis,characterization and study of their cytotoxic activities

Since organotin complexes have been reported to show fewer side effects relative to other heavy metal anticancer compounds, in the present study we report for the first time four novel organotin(IV) derivatives with the general formula R₂SnL₂, where R = methyl (1), n‐butyl (2), phenyl (3), benzyl (4) and L = morpholine‐1‐carbodithioate (MCDT). The newly synthesized ligand was monodentate or bidentate, coordinating through a sulfur atom. The complexes were synthesized by directly mixing, refluxing and stirring the ligand, with diorganotin(IV) dichlorides in a suitable solvent. The complexes were found to be pure and their solid and solution phase structural configuration was investigated by FT‐IR, multinuclear NMR (¹ H, ¹³ C, ¹¹⁹Sn) and mass spectrometry. Complex 2 was also studied for its thermal decomposition by thermogravimetry and differential thermal analysis. The results obtained on the basis of these techniques are in full concurrence with the proposed 1:2 (Sn:L) stoichiometry. The cytotoxic activity of the MCDT and diorganotin(IV) complexes (1–4) was tested against tumor cell lines – human cervix carcinoma HeLa and human myelogenous leukemia K562 – and normal immunocompetent cells: peripheral blood mononuclear cells PBMC. Results of bioassay demonstrated that organotin derivatives were in general more active than the anticancer drug cisplatin. Copyright © 2012 John Wiley & Sons, Ltd.     

Diorganotin(IV) dithiocarbamate complexes as chromogenic sensors of anion binding

One dinuclear chlorodiphenyltin (IV) dithiocarbamate complex (1) and four mononuclear complexes of general formula Ph₂Sn(S₂CNR)Cl (2, 3, 5, and 6) have been synthesized and characterized both in solid-state and solution. X-ray structures for complexes 1, 3 and 6 demonstrated a five-coordination geometry around of tin atoms, in which dithiocarbamate ligand chelates asymmetrically the metal center. As shown by ¹¹⁹Sn NMR spectroscopy, five-coordination geometry observed in the solid-state remains in solution. The stability of these chlorodiphenyltin(IV) dithiocarbamate complexes in the presence of biologically relevant anions such as acetate, dicarboxylates of general formula ^?OOC-(CH₂)_n-COO^? (n = 2–8), dihydrogenphosphate, hydrogensulfate, and halides has been examined in acetonitrile solutions. For all of these organotin(IV) complexes the displacement of the coordinated ligands (i.e., chloride and dithiocarbamate) from the organotin(IV) moiety occurred in the presence of monoanions like acetate, dihydrogenphosphate, hydrogensulfate and fluoride. A stepwise mechanism for ligand exchange is proposed based on UV–Vis, ¹H, ¹³C and ¹¹⁹Sn spectroscopic data, as well as mass spectrometry. From UV–Vis titration experiments it was found that dicarboxylates with small spacers like malonate and succinate, acted differently in the exchange of the dithiocarbamate group in comparison to other monoanionic O donor ligands or dicarboxylates with longer chains, perhaps by following an intramolecular displacement of the coordinated ligand.The lability of these organotin(IV) dithiocarbamate compounds in solution hampers their use as stably host for anions, however, by taking advantage of the intrinsic chromogenic properties of free dithiocarbamate anions, or by attaching dithiocarbamate groups to well-known fluorescent moieties such as antracene, these complexes can sense the presence of O-donor anions at very low concentrations by displacement of the metal-coordinated dithiocarbamate.     

Triorganotin(IV) complexes with substituted benzeneseleninic acids: syntheses,characterization, crystal structures,and antitumor activity

Nine new organotin(IV) selenites have been prepared by the reaction of 2-methylbenzeneseleninic acid, 2-methoxybenzeneseleninic acid, 4-isopropylbenzeneseleninic acid, and the corresponding triorganotin(IV) chloride with sodium ethoxide in methanol. The complexes have been characterized by elemental analysis, FT-IR, (¹H, ¹³C, and ¹¹⁹Sn) NMR spectroscopy, and thermogravimetric analysis. Except for 3, 6, and 9, all of the complexes were also characterized by X-ray crystallography diffraction analyses. The structural analyses reveal that 1, 2, 4, 5, 7, and 8 exhibit 1-D infinite chain structures which are generated by bidentate oxygen atoms and five-coordinated tin. Complex 5 forms a 2-D organotin framework linked by intermolecular C–H?···?O interactions. Additionally, 1 and 2 were tested for antitumor activity in vitro.     

Structural investigations on diorgano- and triorganotin(IV) derivatives of [meso-tetra(4-sulfonatophenyl)porphine] metal chlorides

Several new complexes of organotin(IV) moieties with MCl_n[meso-tetra(4-sulfonatophenyl)porphine], (R₂Sn)₂MCl_n[meso-tetra(4-sulfonatophenyl)-porphinate]s and (R₃Sn)₄MCl_n [meso-tetra(4-sulfonatophenyl)porphinate]s, [M = Fe(III), Mn(III): n = 1, R = Me, n-Bu; Ph; M = Sn(IV): n = 2, R = Me, n-Bu] have been synthesized and their solid state configuration investigated by infrared (IR) and Mössbauer spectroscopy, and by ¹H and ¹³C NMR in D₂O.The electron density on the metal ion coordinated inside the porphyrin ring is not influenced by the organotin(IV) moieties bonded to the oxygen atoms of the side chain sulfonatophenyl groups, as it has been inferred on the basis of Mössbauer spectroscopy and, in particular, from the invariance of the isomer shift of the Fe(III) and Sn(IV) atoms coordinated into the porphyrin square plane of the newly synthesized complexes, with respect to the same atoms in the free ligand.As far as the coordination polyhedra around the peripheral tin atoms are concerned, infrared spectra and experimental Mössbauer data would suggest octahedral and trigonal bipyramidal environments around tin, in polymeric configurations obtained, respectively, in the diorganotin derivatives through chelating or bridging sulfonate groups coordinating in the square plane, and in triorganotin(IV) complexes through bridging sulfonate oxygen atoms in axial positions.The structures of the (Me₃Sn)₄Sn(IV)Cl₂[meso-tetra(4-sulfonatophenyl)porphinate] and of the two model systems, Me₃Sn(PS)(HPS) and Me₂Sn(PS)₂ [HPS = phenylsulfonic acid], have been studied by a two layer ONIOM method, using the hybrid DFT B3LYP functional for the higher layer, including the significant tin environment. This approach allowed us to support the structural hypotheses inferred by the IR and Mössbauer spectroscopy analysis and to obtain detailed geometrical information of the tin environment in the compounds investigated.¹H and ¹³C NMR data suggested retention of the geometry around the tin(IV) atom in D₂O solution.     

Synthesis, spectral characterization and X-ray crystal structure of biologically active organotin(IV) 3-[(3′,5′-dimethylphenylamido)]propanoates

A new ligand was prepared by reacting 3,5-dimethylaniline with succinic anhydride in glacial acetic acid at room temperature. A series of organotin(IV) carboxylates were prepared by reacting the ligand with R₂SnCl₂/R₃SnCl (R?=?Me, Bu, Ph, Oct) in 1:2/1:1 molar ratio. The synthesized complexes were characterized by elemental analyses, FT-IR, multinuclear magnetic resonance (¹H and ¹³C) and mass spectrometry. The structures of the ligand (HL) and complex (5) were determined by single crystal X-ray diffraction analysis. FT-IR data shows that the coordination takes place through both carboxylate oxygen atoms. NMR data confirm the tetrahedral geometry in solution. In the crystal structure of ligand (HL), centrosymmetrically related molecules are linked into dimers by N?CH??O hydrogen bonding interactions, while in complex (5) coordination around the tin atom is trigonal bipyramidal, with the carbon atoms of the methyl groups occupying the equatorial plane and the O atoms of symmetry-related ligands at the apices. Organotin(IV) complexes were also screened for their antibacterial and antifungal activities, and the results suggested that the synthesized complexes are better antimicrobial agents as compared to the free ligand.     

Assembly of triorganotin chloride with selenite ligands to macrocyclic,zigzag, helical,and linear structures: syntheses,characterizations, and crystal structures of [R3Sn(O2SeC6H4-4-Et)] n and [R3Sn(O2SeC6H4-2-Et)] n (R = Me,C6H5) complexes

Four new triorganotin(IV) complexes, [R₃Sn(O₂SeC₆H₄-4-Et)]₄ (R = Me 1), [R₃Sn(O₂SeC₆H₄-4-Et)] _n (R = Ph 2), [R₃Sn(O₂SeC₆H₄-2-Et)] _n (R = Me 3; Ph 4) have been synthesized by the treatment of 4-ethylbenzeneseleninic acid, 2-ethylbenzeneseleninic acid, and the corresponding triorganotin(IV) chloride with sodium ethoxide in methanol. All of the complexes were characterized by elemental analysis, FT-IR, NMR (¹H, ¹³C, and ¹¹⁹Sn) spectroscopy, TGA, and X-ray crystallography. Crystal structures show that all of the complexes are generated by the bidentate oxygen atoms and the five-coordinated tin centers with trigonal bipyramid geometry. The structural analyses reveal that complex 1 has a centrosymmetric tetranuclear triorganotin selenite with 16-membered macrocycle, which is formed by trimethyltin and ligand alternate linking. A series of C–H···O and π–π stacking interactions in complex 1 play an important function in the supramolecular aggregation. Complex 3 has two 1D spring-like chiral helical chains and crystallizes in the monoclinic space group P2₁, which is chiral. Complex 2 and 4 are both 1D infinite neutral chain polymers and complex 2 forms a 2D supramolecular framework through intermolecular C–H···O interactions.