Synthesis,spectral and biological studies of organotin(IV) complexes of heteroscorpionate

A heteroscorpionate ligand, potassium hydrobis(benzoato)(salicylaldehyde)borate (KL), has been synthesized. This was converted into organotin complexes R₂SnL₂ and R₃SnL complexes by mixing and stirring with a methanolic solution/suspension of organotin chloride. The ligand and its complexes were characterized by elemental analyses and spectral studies (IR, ¹H NMR, ¹³C NMR, ESI mass spectra and Thermo gravimetric analysis (TGA)). Antibacterial and antifungal studies of these compounds were evaluated by the disc diffusion method at variable concentration against three species of bacteria (Staphylococcus aureus, Klebsiella pneumonia and Bacillius subtillis) and two species of fungi (Asperjillius fiavus and Candida albicans). It was found that triorganotin derivatives (R₃SnL) of the ligand were more effective as compared with diorganotin derivatives (R₂SnL₂). The organotin complexes of borates were tested for their algicidal activity on the cyanobacterial strains Aulosira fertilissma, Anabaena species, Anabaena variabilis and Nostoc muscorum and showed high to moderate toxicity towards the above species. The ligand and its complexes were also tested for its pH effect on soil in vitro for a duration of more than one month and it was found that they are able to kill pests without damaging the soil quality. Copyright © 2006 John Wiley & Sons, Ltd.     

Gold(I) and platinum(II) complexes with a new diphosphine ligand based on the cyclotriphosphazene platform

A new diphosphine ligand assembled on the cyclotriphosphazene platform forms linear chelate and dimetallic bridged complexes with Au(I) and a cis-chelate complex with Pt(II).     

Preparation and structural studies on organotin(IV) complexes with flavonoids

Fourteen complexes of di-n-butyltin(IV)²⁺ cations with flavonoid glycosides (rutin, hesperidin, 2′,4′,3-trihydroxy-5′,4-dimetoxychalkone 4-rutinoside) and flavonoid aglycones (quercetin, morin, hesperitin and sorte flavones) were prepared. The composition of the complexes was determined by standard analytical methods. The results showed that complexes containing diorganotin(IV)²⁺ moiety and the ligand in 1∶1, 2∶1 or 3∶1 ratio are formed. The FTIR spectra were consistent with the presence of Sn-O (phenol or carbohydrate) vibration in the compounds. The structure of the complexes was measured by Mössbauer spectroscopy. Comparison of the experimental quadrupole splitting with those calculated on the basis of partial quadrupole splitting concept revealed that the complexes are of four types: with the central tin atoms surrounded by donor atoms in a purely trigonal-bipyramidal, octahedral+trigonal-bipyramidal, trigonal-bipyramidal+tetrahedral and octahedral+tetrahedral arrangement. This procedure also distinguished between the different structural isomers of both trigonal-bipyramidal and octahedral complexes. Conclusions could therefore be drawn on the factors determining which of the isomers are formed in the systems. The Mössbauer parameters obtained for organotin(IV)-flavonoid complexes were compared with those measured for organotin(IV)-carbohydrate complexes.     

Copper(II) chloride complexes with multimodal ligands based on the cyclotriphosphazene platform

The reaction of hexakis(2-pyridyloxy)cyclotriphosphazene (L) and hexakis(4-methyl-2-pyridyloxy)cyclotriphosphazene (MeL) with copper(ii) chloride afford the complexes [CuLCl(2)], [(CuCl(2))(2)(MeL)], [CuLCl]PF(6) and [Cu(MeL)Cl]PF(6). The single-crystal X-ray structure of [CuLCl(2)] shows the copper ion to be in a square based pyramidal distorted trigonal bipyramidal (SBPDTBP) environment (tau= 0.47) with L acting as a kappa(3)N donor, coordinating via the nitrogen atoms from two non-geminal pyridyloxy pendant arms, a nitrogen atom in the phosphazene ring and two chloride ions. In the dimetallic complex, [(CuCl(2))(2)(MeL)], the geometry about both (symmetry related) copper(ii) centres is also SBPDTBP (tau= 0.57) with a 'N(3)Cl(2)' donor set. In the monocation of [CuLCl]PF(6), L acts as a kappa(5)N donor, bonding to the copper(ii) centre through the nitrogen atoms of four pyridyloxy pendant arms, a phosphazene ring nitrogen atom and a chloride ion to give an elongated rhombic octahedral coordination sphere. The phosphazene ring atoms remain virtually coplanar in all three structures as a consequence of the phenoxy-hinge, which links the pyridine pendant donors to the cyclotriphosphazene platform, allowing the formation of six-membered chelate rings. The spectroscopic (mass spectral, EPR and electronic) and magnetic properties of the complexes are discussed. The EPR and variable temperature magnetic susceptibility results for the dicopper complex, [(CuCl(2))(2)(MeL)], point to a very weak electronic interaction between the metal atoms.     

Biological studies of organotin(IV) complexes with 2-mercaptopyrimidine

The known organotin(IV) complexes with 2-mercaptopyrimidine (L) [Me₂SnL₂] (1), [Buⁿ ₂SnL₂] (2), [Ph₂SnL₂] (3), and [Ph₃SnL] (4) were synthesized using a new approach. The effect of the synthesized compounds on peroxidation of fatty acids (oleic and linoleic) was studied. Complexes 1–4 promote the peroxidation of oleic acid. Their effect on the enzymatic peroxidation of linoleic acid with lipoxygenase was compared with that of cisplatin and in vitro cytoxicity against sarcoma cancer cells was determined. The antiproliferative effect of complexes 2–4 was demonstrated. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 737–743, April, 2007.     

Synthesis, spectral characterization and biological studies of some organotin(IV) complexes of L-proline, trans-hydroxy-L-proline and L-glutamine

New organotin(IV) complexes of the general formula R3Sn(L) (where R=Me, n-Bu and HL=L-proline; R=Me, Ph and HL=trans-hydroxy-L-proline and L-glutamine) and R2Sn(L)2 (where R=n-Bu, Ph and HL=L-proline; R=Ph, HL=trans-hydroxy-L-proline) have been synthesized by the reaction of RnSnCl(4-n) (where n=2 or 3) with sodium salt of the amino acid (HL). n-Bu2Sn(Pro)2 was synthesized by the reaction of n-Bu2SnO with L-proline under azeotropic removal of water. The bonding and coordination behavior in these complexes have been discussed on the basis of IR and 119Sn M?ssbauer spectroscopic studies in the solid-state. Their coordination behavior in solution has been discussed with the help of multinuclear (1H, 13C and 119Sn) NMR spectral studies. The 119Sn M?ssbauer and IR studies indicate that L-proline and trans-hydroxy-L-proline show similar coordination behavior towards organotin(IV) compounds. Pentacoordinate trigonal-bipyramidal and hexacoordinate octahedral structures, respectively, have been proposed for the tri- and diorganotin(IV) complexes of L-proline and trans-hydroxy-L-proline, in which the carboxylate group acts as bidentate group. L-glutamine shows different coordination behavior towards organotin(IV) compounds, it acts as monoanionic bidentate ligand coordinating through carboxylate and amino group. The triorganotin(IV) complexes of L-glutamine have been proposed to have trigonal-bipyramidal environment around tin. The newly synthesized complexes have been tested for their antiinflammatory and cardiovascular activities. Their LD50 values are >1000 mg kg-1.     

New organotin(IV) ascorbates: synthesis, spectral characterization, biological and potentiometric studies

New organotin(IV) ascorbates of the general formulae R(3)Sn(HAsc) (where R = Me , n-Pr, n-Bu and Ph) and R(2)Sn(Asc) (where R = n-Bu and Ph) have been synthesized by the reaction of R(n)SnCl(4-n) (where n = 2 or 3) with monosodium-l-ascorbate. The bonding and coordination behaviour in these complexes are discussed on the basis of UV-Vis, IR, Far-IR, (1)H and (13)C NMR, and (119)Sn Mossbauer spectroscopic studies. L-Ascorbic acid acts as a monoanionic bidentate ligand in R(3)Sn(HAsc) coordinating through O(1) and O(3). The Mossbauer studies together with IR and NMR studies suggest that for these polymeric derivatives, the polyhedron is trigonal bipyramidal around tin with three organic groups in the equatorial positions. In R(2)Sn(Asc), L-ascorbic acid acts as dianionic tetradentate ligand and a polymeric structure with octahedral geometry around tin with trans organic groups has been tentatively proposed. The complexes have been assayed for their anti-inflammatory and cardiovascular activity. Ph(2)Sn(Asc) has been found to show the highest activity among the studied complexes. It is suggested on the basis of potentiometric studies of Me(2)Sn(IV) and Me(3)Sn(IV) systems with L-ascorbic acid that under physiological conditions (pH = 7.0) Me(2)Sn(HAsc)(OH) (approximately 60%), Me(2)Sn(OH)(2) (approximately 40%) and Me(3)Sn(HAsc) (approximately 60%), Me(3)Sn(OH) (approximately 40%), respectively, are existing, which may be responsible for their biological activities.     

Biological activity studies on organotin(IV) complexes and parent compounds

This review summarized the literature and own data on the parent organotin(IV) compounds and complexes formed with biologically active ligands.     

Equilibrium studies of organotin(IV) complexes with vitamin B(6)

The complex-formation equilibria of dimethyltin(IV), trimethyltin(IV) and tributyltin(IV) with pyridoxamine were investigated in dioxane-water mixtures and at different temperatures using a potentiometric technique. The stepwise formation constants of the complexes formed in solution were calculated using the non-linear least-square program MINIQUAD-75. The effect of dioxane as a solvent on the protonation constants of pyridoxamine and the formation constants of organotin(IV) complexes was discussed. The thermodynamic parameters DeltaH degrees and DeltaS degrees calculated from the temperature dependence of the equilibrium constants were investigated. The concentration distribution of the various complex species was evaluated as a function of pH.     

Synthesis and spectroscopic studies of diorganotin(IV) adducts based on cyclotriphosphazene scaffolds with exocyclic pyrazolyl substituents

Functionalized cyclotriphosphazenes with four pyrazolyl substituents have been employed for the synthesis of two new organotin complexes. These new compounds have been characterized by elemental analysis and IR, ¹H, ³¹P and ¹¹⁹Sn NMR spectroscopy. On the basis of these data, pyrazolylcyclotriphosphazene is bis-bidentate neutral ligand coordinating to two SnMe₂Cl₂ molecules in the resulting adducts. Coordination occurs only via the pyrazolyl nitrogens; cyclotriphosphazene ring nitrogens are not involved in coordination. The ¹¹⁹Sn NMR data are consistent with increasing of coordination number of tin(IV) in solution.     

Synthesis and characterization of new organotin(IV) complexes with polyfunctional ligands

New mono-, di- and tri-organotin(IV) derivatives containing the neutral bis(2-pyridylthio)methane ligand, [(pyS)₂CH₂] and tris(2-pyridylthio)methane ligand, [(pyS)₃CH] have been synthesized from reaction with SnR_nCl_4−n (R = Me, ⁿBu, Ph and Cy, n = 1-3) acceptors. Mono-nuclear adducts of the type {[(pyS)₂CH₂]R_nSnCl_4−n} and {[(pyS)₃CH]R_nSnCl_4−n} have been obtained and characterized by elemental analyses, FT-IR, ESI-MS, multinuclear (¹H and ¹¹⁹Sn) NMR spectral data. The ¹H and ¹¹⁹Sn NMR and ESI-MS data suggest for the triorganotin(IV) derivatives a complete dissociation of the compounds in solution. The mono- and di-organotin(IV) derivatives show a greater stability in solution, and their spectroscopic data are in accordance with the existence of six-coordinated RSnCl₃N₂ or R₂SnCl₂N₂ species.     

Synthesis and spectroscopic studies of new organotin(IV) complexes with tridentate N- and O-donor Schiff bases

The Schiff bases H₂L¹ and H₂L² have been prepared by the reaction of 2-amino-4-chlorophenol with pyrrole-2-carbaldehyde and 2-hydroxy-1-naphtaldehyde, respectively, and HL³ from reaction of 2-(aminomethyl)pyridine with 2-hydroxy-1-naphtaldehyde. Organotin complexes [SnPh₂(L¹)] (1), [SnPh₂(L²)] (2), [SnMe₂(L²)] (3) and [SnPhCl₂(L³)] (4) were synthesized from reaction of SnPh₂Cl₂ and SnMe₂Cl₂ with these Schiff bases. The synthesized complexes have been investigated by elemental analysis and FT-IR, ¹H NMR and ¹¹⁹Sn NMR spectroscopy. In complexes the Schiff bases are completely deprotonated and coordinated to tin as tridentate ligands via phenolic oxygen, pyrrolic, and imine nitrogens in 1, two phenolic oxygens and imine nitrogen in 2 and 3, and phenolic oxygen, imine and pyridine nitrogens in 4. The coordination number of tin in 1, 2, and 3 is five and in 4 is six.     

Thermal studies on some organotin(IV) complexes with piperidine and 2-aminopyridine dithiocarbamates

The complexes of piperidine dithiocarbamate, 2-aminopyridine dithiocarbamate and organotin(IV) of the type R₃Sn(L¹), R₂Sn(L¹)₂, R₃Sn(L²), R₂Sn(L²)₂, [R=C₆H₅CH₂ (benzyl), p-ClC₆H₄CH₂ (p-chlorobenzyl), L ¹=sodium piperidine dithiocarbamate and L ²=sodium 2-aminopyridine dithiocarbamate] have been synthesised and characterised by spectral studies (IR, UV, ¹H NMR). Thermogravimetric (TG) and differential thermal analytical (DTA) studies have beeen carried out for these complexes and from the TG curves, the order and apparent activation energy for the thermal decomposition reactions have been elucidated. The various thermal studies have been correlated with some structural aspects of the complexes concerned. From DTA curves, the heat of reaction has been calculated.     

Organotin(IV) azepane dithiocarbamates: Synthesis and characterization of the first organotin(IV) complexes with seven-membered cyclic dithiocarbamates

Abstract

We report the synthesis and spectroscopic characterization of the first organotin(IV) complexes with cyclic seven-membered dithiocarbamate ligands: the azepane-1-carbodithioate and the homopiperazine-1,4-bis-carbodithioate with two different organotin entities, di-n-butyltin and tri-cyclohexyltin: [(C₄H₉)₂Sn{S₂CN(CH₂)₆}₂] (3), [(C₆H₁₁)₃Sn{S₂CN(CH₂)₆}] (4), and [(C₆H₁₁)₃Sn}₂ (μ-S₂CN(C₅H₁₀)NCS₂)] (5). Compounds (3–5) are air-stable both in solid-state and in solution, and were characterized by elemental analyses, IR, FAB⁺–MS, and multinuclear NMR (¹H, ¹³C, and ¹¹⁹Sn) spectroscopy. Their molecular structures were unambiguously established by single-crystal X-ray diffraction studies. The geometrical arrangement around the tin atom can be described as distorted octahedral for (3) and distorted trigonal bipyramid for (4) and (5). The coordination mode for both ligands is considered as asymmetric bidentate, as happens in other organotin(IV) dithiocarbamates. Furthermore, (4) and (5) do not exhibit intermolecular secondary interactions, while (3) presents intermolecular interactions between the tin and a sulfur atom with the reciprocally neighboring molecule, giving rise to a zig-zag polymeric structure.     

New adducts of diorganotin(IV) chlorides with a new multifunctional schiff base ligand: Synthesis and spectral properties

Three novel Schiff base adducts [SnMe₂Cl₂(Hcdacacen)] (1), [SnBu₂Cl₂(Hcdacacen)₂] (2) and [SnPh₂Cl₂(Hcdacacen)₂] (3) have been synthesized by reaction of SnR₂Cl₂ (R = Me, Bu and Ph) with a new Schiff base ligand methyl-2-[2-(acetylacetoneimino)ethylamino]-1-cyclopentene-1-dithiocarboxylate (Hcdacacen). The ligand and complexes were characterized by elemental analysis and spectroscopic studies. Spectroscopic data suggest that Hcdacacen exists predominately in ketamine tautomeric form and in all complexes acts as a monodentate neutral ligand coordinates to the metal through oxygen atom, while the sulfur atom and imine nitrogen is not involved in the coordination to the tin.     

Toxicological and pesticidal studies on novel bioactive sulfonamide imine organotin(IV) complexes

Toxicological, pesticidal and stereochemical aspects of organotin(IV) complexes with a sulfonamide imine ligand having an N^∩N donor system are described with the support of elemental analysis, IR, UV, ¹H NMR, ¹³C NMR and ¹¹⁹Sn NMR spectroscopy. The spectral data suggest that the ligand acts in a monobasic bidentate manner coordinating through the nitrogen atom. The complexes have been characterized on the basis of molecular weight determinations, conductivity measurements, and magnetic measurements. The isolated products are coloured solids, soluble in dimethylsulfoxide, dimethylformamide (DMF) and methanol. All the complexes are monomeric in nature, as indicated by their molecular weight determinations. Conductivity measurements in dry DMF show them to be non‐electrolytes. From the analyses of these studies the donor sites of the ligand are located and the geometries of the donor environment around the tin(IV) acceptor centres proposed. The ligand and its metal complexes are tested in vitro against a number of pathogenic fungal and bacterial strains and the findings are discussed. Emphasis has been given to the nematicidal properties. Copyright © 2003 John Wiley & Sons, Ltd.     

Luminescent organotin complexes with the ligand benzil bis(benzoylhydrazone)

Three organotin complexes have been synthesised by reaction of the ligand benzil bis(benzoylhydrazone) LH₂ with SnR₂Cl₂ or SnR₃Cl (R = Me, Bu, Ph). In all the compounds the ligand is doubly deprotonated and behaves as N₂O₂ tetradentate chelate, leading to distorted octahedral arrangements with the ligand in the equatorial plane and the organic groups in the axial positions. The complexes have been fully characterised by spectroscopic techniques including ¹³C and ¹¹⁹Sn NMR in solution and in the solid state, which confirm that the structure found in the solid state is retained in chloroform solution, and two of them by single crystal X-ray diffraction. The luminescent properties of the ligand and its complexes have also been tested as well as the effect of pH, the addition of acetone and the ionic strength over the luminescence intensity.     

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.