The Synthesis and Biological Activity of two Organostannoxane Ladder‐like Complexes Derived from Schiff Bases

Two complexes containing (nBu)₂Sn₄O₄L₄ (L = salicylaminoaryl alcohols) were synthesized and characterized by elemental analysis and ¹H, ¹³C, and ¹¹⁹Sn NMR as well as IR spectroscopy. The crystal structure of complex 2 . 2 was determined by X‐ray crystallography. It consists of three, four‐member Sn₂O₂ rings in a ladder‐like, structural arrangement with four tin centers, bridged by four, three‐coordinate μ₃‐oxygen atoms. The dimeric distannoxane have two different, pentacoordinate tin atoms, where the Schiff base acts as monodentate ligand. The complexes were subjected to a thiobarbituric acid, reactive substance (TBARS) assay, which displayed a higher antioxidant activity than the α‐tocopherol and Butylated hydroxy toluene (BHT), used as positive controls.     

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.     

The Synthesis of Quinoline‐based Tin Complexes with Pendant Schiff Bases

Whilst pursuing the synthetic utility of quinoline‐based tin complexes, Me₂Sn(Quin‐NO₂)₂ ( 1 ) and Ph₂Sn(Quin‐NO₂)₂ ( 2 ) (Quin‐NO₂ = 5‐nitroquinolino‐8‐oate) were synthesized bearing coordinatively inert nitro groups. Conventional reduction methodologies successfully converted 1 to Me₂Sn(Quin‐NH₂)₂ ( 3 ) and 2 to Ph₂Sn(Quin‐NH₂)₂ ( 4 ) (Quin‐NH₂ = 5‐aminoquinolino‐8‐oate). The synthetically useful amine groups proved difficult to exploit in the presence of the central tin atom, however, a complete Schiff base functionalized Sn complex of the dimethyltin pro‐ligand Me₂Sn(Quin‐py)₂ ( 6 ) was successfully synthesized from 5‐[(pyridin‐2‐ylmethylene)amino]quinolin‐8‐ol (HQuin‐py; 5 ) in good yield via an alternative strategy exploiting the oxophilic tendencies of tin. All species were fully characterized by NMR (including ¹¹⁹Sn NMR spectroscopy), HR‐ESI MS and single‐crystal X‐ray diffraction, and preliminary studies of their supramolecular potential are also discussed.     

Synthese,Struktur und Eigenschaften von [nacnac]MX3‐Verbindungen (M = Ge,Sn; X = Cl,Br, I)

Synthesis, Structure, and Properties of [nacnac]MX₃ Compounds (M = Ge, Sn; X = Cl, Br, I) Reactions of [nacnac]Li [(2,6‐ⁱPr₂C₆H₃)NC(Me)C(H)C(Me)N(2,6‐ⁱPr₂C₆H₃)]Li ( 1 ) with SnX₄ (X = Cl, Br, I) and GeCl₄ in Et₂O resulted in metallacyclic compounds with different structural moieties. In the [nacnac]SnX₃ compounds (X = Cl 2 , Br 3 , I 4 ) the tin atom is five coordinated and part of a six‐membered ring. The Sn–N‐bond length of 3 is 2.163(4) Å and 2.176(5) Å of 4 . The five coordinated germanium of the [nacnac]GeCl₃ compound 5 shows in addition to the three chlorine atoms further bonds to a carbon and to a nitrogen atom. In contrast to the known compounds with the [nacnac] ligand the afore mentioned reaction creates a carbon–metal‐bond (1.971(3) Å) forming a four‐membered ring. The Ge–N bond length (2.419(2) Å) indicates the formation of a weakly coordinating bond.     

Schiff base supported mononuclear organotin(IV) complexes: Syntheses,structures and fluorescence cell imaging

Three mononuclear organotin(IV) complexes supported by Schiff bases have been synthesized. The complexes [(C₆H₅)₂Sn(L)] ( 1 ), [(t‐Bu)₂Sn(L)] ( 2 ) and [(t‐Bu)₂Sn(L')] ( 3 ) (L, L' = deprotonated Schiff bases) were obtained in good yield by the reaction of Schiff bases H ₂ L or H ₂ L′ with corresponding diorganotin dichlorides respectively. All newly synthesized complexes were characterized by means of FT‐IR spectroscopy, elemental analysis and multinuclear (¹H, ¹³C and ¹¹⁹Sn) NMR spectroscopy. In addition, single crystal X‐ray diffraction analyses were employed to establish the solid state molecular structures of these complexes. The structures of 1 – 3 reveal that all complexes are mononuclear with a five‐coordinated tin(IV) centre in it. The absorption and emission properties of all complexes have been investigated. Moreover, cytotoxicity and fluorescence cell imaging studies of theses complexes have been performed.     

Mössbauer and NMR characterization of tin octoate: Neat and residues in RTV foams

We have investigated hydrolysis and oxidation effects on tin octoate and on tin-octoate residues in RTV polysiloxane foams by means of Nuclear Magnetic Resonance (NMR) and Mössbauer spectroscopy (MS). ¹¹⁹Sn NMR showed the presence of various tin species whereas ¹¹⁹Sn MS detected the presence of two oxidation states: Sn(II) and Sn(IV). The relative abundance of Sn(IV) increased as both the tin octoate and the foam aged. Foams were also solvent extracted and no selective extraction of one tin oxidation state was observed; both oxidation states were detected. ¹³C NMR indicated that octanoic acid is present in the tin octoate and in the foams as a residue. MS data showed that aging treatments of the foams and of the neat catalyst have a great effect on the tin oxidation state. The two spectroscopic methods complement each other in following the effects of hydrolysis and oxidation.     

Synthesis and characterization of tribenzyltin(IV) and dibenzyltin(IV) complexes of 2-{[(2Z)-3-hydroxy-1-methyl- 2-butenylidene]amino}acetic acid: Crystal structure of tribenzyl{2-{[(2Z)-3-hydroxy-1-methyl-2-butenylidene] amino}acetato}tin(IV)

Reactions of equimolar quantities of potassium 2-{[(2Z)-3-hydroxy-1-methyl-2-butenylidene]amino}acetate, with R _n SnX_4?n (R: benzyl– and n=2 or 3) in methanol yielded products of compositions LHSn(PhCH₂)₃ and LSn(PhCH₂)₂, respectively. The complexes were characterized by microanalysis, IR, NMR (¹H, ¹³C, ¹¹⁹Sn) and ^119mSn Mössbauer spectroscopy. A full characterization of the structure of the complex, tribenzyl{2-{[(2Z)-3-hydroxy-1-methyl-2-butenylidene]amino}acetato}tin(IV), was carried out by single crystal X-ray crystallography. The compound exists as centrosymmetric dimers in which two ligand molecules bridge the two tin centres. Each of the tin atoms in the dimeric unit is five coordinate in an approximately trigonal bipyramidal configuration, with carbon atoms in the equatorial positions and oxygen atoms arranged axially.     

Zinn(IV)-Komplexe mit dreizähnigen diaciden Liganden — 119Sn-NMR und 119mSn-Mössbauer-spektroskopische Untersuchungen

Tin(IV) Complexes with Tridentate Diacidic Ligands — ¹¹⁹Sn NMR and ^119mSn Mössbauer Studies The tin(IV) chelates of tridentate diacidic azomethines of acetylacetone resp. salicylaldehyde with benzoylhydrazine, thiobenzoylhydrazine, 2-hydroxyaniline and 2-mercaptoaniline as well as with the ligands 2-(2′-hydroxy-4-methylphenyl)-6-(2″-hydroxyphenyl)pyridine, 2-(2′-hydroxyphenyl)-8-quinolinol and 2.6-diphenacylpyridine were synthesized. The compounds were characterized by IR-, UV/VIS-, MS-, ¹¹⁹Sn NMR and ^119mSn Mössbauer spectroscopy. They exist as a mixture of geometrical isomers.     

Synthesis of ONO-Ligated Tetrylenes Based on 2,6-bis(2-Hydroxyphenyl)pyridines: Influence of Ligand Sterics on the Structure of the Products

A series of novel tetrylenes based on three 2,6-bis(2-hydroxyphenyl)pyridines 4 a – 4 c have been obtained by the reaction of Lappert's tetrylenes E[N(SiMe₃)₂]₂ (E=Ge, Sn) with corresponding tridentate pyridine-linked phenol-based ligands. It was found that the structure of the ligand and the size of the atom of the group 14 element drastically affect the structure of the reaction product. Ligand 4 c with a bulky tert-butyl group leads to monomeric tetrylenes, while ligands with less bulky groups lead to bis-ligand derivatives of M(IV) (M=Ge, Sn) and a coordination polymer. Also, derivatives of germanium (IV) and tin (IV) were obtained by the metathesis reaction of MCl₄ (M=Ge, Sn) with lithium phenoxides. The compositions and structures of the novel compounds were established by elemental analysis and ¹H, ¹³C, ¹¹⁹Sn ( 5 – 7 ), ¹H DOSY ( 6 ) NMR spectroscopy, in the solid state by X-ray diffraction analysis (germylene 10 , stannylene 6 , Ge⁴⁺ compound 8 , Sn⁴⁺ compound 7 ) and ¹¹⁹Sn Mössbauer spectrum of tin complex 6 . All the synthesized tetrylenes are monomeric. Tetrylenes 6 and 10 were characterized by cyclic voltammetry. A study of the redox behavior of 6 , 10 by cyclic voltammetry on a glassy carbon working electrode in acetonitrile solution of 0.1 M Bu₄NPF₆ as a supporting electrolyte showed that these compounds can be both oxidized and reduced electrochemically in the accessible potential range.     

N → Sn coordination in the complexes of tin halides with pyridine: A comparison between Sn(II) and Sn(IV)

The experimentally well‐known complexation of tin(II) and tin(IV) halides with pyridine (py) leads to structures showing N → Sn coordination. In the present work, the complexes SnX_n·mpy (where X = F, Cl, Br, I; n = 2, 4; m = 1, 2) possessing this kind of coordination were studied using a computational quantum chemical approach. Various aspects in the theoretical picture of these complexes were examined to find similarities and differences in their N → Sn coordination. The aspects included, among others, the physical nature of intermolecular interactions, and their role in establishing the structure and energetic stabilization of the complexes. In this context, the effect of tin valency was inspected in great detail. As proven by several theoretical methods, a largely ionic character with a certain covalent component can be attributed to the studied N → Sn coordination, irrespective of tin valency. All complexes are destabilized by py‐py and three‐body interactions, but the Sn(II) complexes experience it to a greater extent. Marked differences are observed in the structural behavior of N → Sn and SnX_n during complex formation. This affects the energetics of complexation and, in consequence, the penta‐coordinated Sn(IV) center shows a higher propensity to expand its coordination number, compared with the tri‐coordinated Sn(II) center. The present study supplements the experimental characterization of SnX_n·mpy and, in general, it sheds light on the coordination of heteroaromatic nitrogen to tin. The survey of the Cambridge Structural Database revealed that such coordination occurred in a number of crystal structures.     

Syntheses,characterizations, and crystal structures of tri‐ and diorganotin (IV) derivatives with 2‐mercapto‐5‐methyl‐1,3,4‐thiadiazole

A series of organotin(IV) complexes with 2‐mercapto‐5‐methyl‐1,3,4‐thiadiazole (HL) of the type R₃ Sn(L) (R = Me 1 ; Bu 2 ; Ph 3 ; PhCH₂ 4 ) and R₂Sn(L)₂ (R = CH₃ 5 ; Ph 6 ; PhCH₂ 7 ; Bu 8 ) have been synthesized. All complexes 1–8 were characterized by elemental analysis, IR,¹H, ¹³ C, and ¹¹⁹Sn NMR spectra. Among these, complexes 1 , 3 , 4 , and 7 were also determined by X‐ray crystallography. The tin atoms of complexes 1 , 3 , and 4 are all penta‐coordinated and the geometries at tin atoms of complexes 3 and 4 are distorted trigonal–bipyramidal. Interestingly, complex 1 has formed a 1D polymeric chain through Sn and N intermolecular interactions. The tin atom of complex 7 is hexa‐coordinated and its geometry is distorted octahedral. © 2006 Wiley Periodicals, Inc. Heteroatom Chem 17:353–364, 2006; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20215     

Synthesis,Spectroscopic Characterization,Antimicrobial, Pesticidal and Nematicidal Activity of Some Nitrogen‐Oxygen and Nitrogen‐Sulfur donor Coumarins based Ligands and their Organotin(IV) Complexes

Series of new tin complexes are synthesized by classical thermal and microwave‐irradiated techniques. The biologically potent ligands 3‐formyl‐4‐chlorocoumarin semicarbazone (L¹H) and 3‐formyl‐4‐chlorocoumarin thiosemicarbazone (L²H), were prepared by the condensation of semicarbazide hydrochloride and thiosemicarbazide in ethanol with the particular ketone by using microwave as well as conventional methods. The tin(IV) complexes have been prepared by mixing Ph₃SnCl/Me₃SnCl/Me₂SnCl₂ in 1:1 and 1:2 molar ratios with monofunctional bidentate ligands. The structures of the ligands and their tin complexes were confirmed by the elemental analysis, melting point determinations, molecular weight determinations, IR, ¹H NMR, ¹³C NMR, ¹¹⁹Sn NMR, UV, mass spectral and X‐ray powder diffraction studies. On the basis of these studies it is clear that the ligands coordinated to the metal atom in a monobasic bidentate mode, by X$^{\cap}$ N donor system. Thus, suitable trigonal bipyramidal geometry for penta‐coordinated state and octahedral geometry for hexa‐coordinated state have been suggested for the 1:1 and 1:2 metal compounds. Both the ligands and their complexes have been screened for their antimicrobial, pesticidal and nematicidal activities. Copyright © 2011 John Wiley & Sons, Ltd.     

Synthesis and crystal structure of triphenyltin and lead complexes with organic peroxides

Crystalline triphenyltin cumyl and tert-butyl peroxides (Ph₃SnOOCMe₂Ph and Ph₃SnOOBu^t, respectively) and triphenyllead cumyl peroxide (Ph₃PbOOCMe₂Ph) were synthesized and characterized by single crystal and powder X-ray diffraction, NMR, FTIR and Raman spectroscopies, TG and DSC analysis. The formation of triphenyltin tert-butyl peroxide in benzene in the presence of a base was proved by ¹¹⁹Sn, ¹³C and ¹H NMR spectroscopy. To the best of our knowledge, the obtained complexes are the first structurally characterized coordination compounds of tin and lead with organic peroxides.     

Organotin Complexes of Alizarin and Purpurin

Five novel organotin complexes with the anthraquinone dyes alizarin (1,2‐dihydroxyanthraquinone) and purpurin (1,2,4‐trihydroxyanthraquinone) were synthesized and characterized by elemental analyses, FTIR and NMR spectroscopy (¹H, ¹³C and ¹¹⁹Sn). The crystal and molecular structures of four complexes were determined by X‐ray diffraction on single crystals: [Bu₂Sn(aliz)(H₂O)]·C₂H₅OH ( A1 ·EtOH), [Bu₂Sn(aliz)(dmso)]₂ ( A3 ), [(Bu₂Sn)₃O(Hpurp)₂] ( P1 ) and [Bu₂Sn(Hpurp)(dmso)]₂ ( P2 ), where H₂aliz = alizarin and H₃purp = purpurin. The coordination mode of the ligands is identical to that found in their Al/Ca complexes, where they act as dianionic tridentate ligands forming five and six‐membered fused chelate rings. The coordination to the tin atoms occurs exclusively via the 1,2‐ phenolate oxygen and the adjacent quinoid oxygen atoms. The complexes A1 , A3 and P1 are dimers with hepta‐coordinated tin atoms in form of a slightly distorted pentagonal bipyramid. The trinuclear complex P2 contains two pentacoordinated and one heptacoordinated tin atoms.     

Synthesis,characterization, and in vitro antibacterial and antifungal studies of tin(IV) thiohydrazide complexes

Reaction of tin dichloride and tin tetrachloride with cyclohexylamine-N-thiohydrazide (ChaThz) [L¹] and 1,3-propanediamine-N-thiohydrazide (PdaThz) [L²] results in [Sn(ChaThz)₂] (1), Sn(ChaThz)₂Cl₂] (2), [Sn(PdaThz)₂] (3), and [Sn(PdaThz)₂Cl₂] (4), in which the thiohydrazide coordinates to tin through imine nitrogen and thioamide sulfur. The ratio metal?:?ligand was 1?:?2 for all complexes. The tin(IV) thiohydrazide complexes were characterized by elemental analysis, IR, UV-Vis, ¹H-NMR, ¹¹⁹Sn NMR, and mass spectral studies. Using the disc diffusion method, the ligands and metal complexes were screened for in vitro antibacterial activities against four pathogenic bacteria, Escherichia coli, Staphylococcus aureus, P. aeruginosa, and Bacillus cereus and for antifungal activities against Aspergillus flavus, A. carbonarius, A. niger, and A. fumigatus. While the tin(IV) complexes exhibited moderate antifungal activities, their parent ligands showed much higher and long-lasting broad spectrum of bioactivity against fungal growth. This was particularly the case for L¹ whose fungal inhibitory activity by the end of the experimental period was comparable and, for the most part, more pronounced than that of AmB. This higher activity of L¹ was maintained specifically against S. Aureus but in general, bacteria were more susceptible to complexes than ligands.     

Mössbauer, NMR and ATR-FTIR spectroscopic investigation of degradation in RTV siloxane foams

The combination of experimental techniques allowed for a comprehensive study of aging processes occurring in RTV siloxane foams. ¹¹⁹Sn Mössbauer spectroscopy demonstrated that tin residues are composed of Sn(II) and Sn(IV) species. The 27-year-old foams showed only Sn(IV) species with a quadrupole-splitting parameter larger than that observed for SnO₂. Solid-state ²⁹Si NMR differentiated between the various functional linkages in the foams, and showed no significant change of the di- to trifunctional linkage ratios. High-resolution NMR, on solvent extract of foams, showed the presence of water, catalyst, plasticizer, and some silicone oligomers. ATR-FTIR demonstrated changes near the surface of the foam when aged with water and with the presence of the tin catalyst. Gamma irradiation at a low dose had little effect on compression sets. The main changes observed for artificially aged and aged in service foams were related to the presence of the tin catalyst.     

Synthesis and characterization of a new tin(IV) complex for fabrication of an organic light-emitting diode (OLED) and photoluminescence properties of the tin oxide core

A new tin(IV) complex, (C₁₃H₁₀NO)[SnCl₄(C₉H₆NO)]·2CH₃OH, was prepared in a facile process and characterized by ¹H, ¹³C, and ¹¹⁹Sn NMR, IR, and UV spectroscopy in addition to single-crystal X-ray diffraction analysis. Current–voltage (I–V) characteristics, photoluminescence (PL), and electroluminescence (EL) properties of the complex have been investigated and an application of the prepared complex in fabrication of an organic light-emitting diode has been demonstrated. The EL of the compound exhibits blue–green emission at 494?nm. Tin(IV) oxide core that resulted from direct thermal decomposition of the complex at 450?°C in air was characterized by X-ray powder diffraction and scanning electron microscopy; then, the PL property was investigated and compared with the PL of the complex. The tin(IV) oxide core showed a band gap of ～3.81?eV determined from the UV/visible absorption spectrum. The tin oxide core showed stable PL with one emission peak centered at 581?nm.     

Synthesis,Crystal Structures,and Properties of (4,4'-Hbipy)2[Sn2(C2O4)3] and (4,4'-Hmbipy)[SnX2] (X = C2O42–, m = 2; X = Cl,m = 0; bipy = bipyridine)

Three new tin coordination compounds (4,4'-Hbipy)₂[Sn₂(C₂O₄)₃] ( 1 ), (4,4'-H₂bipy)[Sn(C₂O₄)₂] ( 2 ), and SnCl₂(4,4'-bipy) ( 3 ) were synthesized under hydro-(solvo-)thermal conditions and their crystal structures were determined by single-crystal X-ray diffraction. Compound 1 exhibits a ionic structure based on discrete [4,4'-Hbipy]⁺ cations and [Sn₂(C₂O₄)₃]^2– anions. These two units are linked via N–H ··· O hydrogen bonds to form a pseudo-one-dimensional zigzag hydrogen-bonded chain. In compound 2 , four-coordinate Sn atoms form monomeric tin dioxalato complexes, which are connected to the doubly protonated [4,4'-H₂bipy]²⁺ cations through N–H ··· O hydrogen bonded to give a one-dimensional zigzag hydrogen-bonded chain. Compound 3 forms a three-dimensional hydrogen-bonded network, in which ¹_∞[SnCl₂(4,4'-bipy)] linear chains are interconnected to each other by C–H ··· Cl hydrogen bonding. The solid-state UV/Vis/NIR diffuse reflectance spectroscopy shows that three compounds are broadband semiconductors. The thermogravimetric analysis evidences the thermal stability of the three compounds up to 175, 201, and 246 °C, respectively.     

119Sn Chemical Shifts in five- and six-coordinate organotin chelates

¹¹⁹Sn chemical shifts, δ(¹¹⁹Sn), relative to Me₄Sn in five- and six-coordinate organotin chelates were measured by means of FT NMR spectroscopy. ¹¹⁹Sn resonances were found to lie between ca. ?90 and ?330 ppm in the five-coordinate compounds and between ca. ?125 and ?515 ppm in the six-coordinate derivatives. thus δ(¹¹⁹Sn) moves upfield by 60–150 ppm with a change of the coordination number of tin from four to five and by 130–200 ppm from five to six. the δ(¹¹⁹Sn) values were shifted depending on the nature of chelating ligands and this shift was discussed in terms of the bonding between the ligand and tin. Replacement of methyl groups attached to tin by phenyl groups in five- and six-coordinate compounds induces upfield shifts in δ(¹¹⁹Sn) parallel to those found in four-coordinate organotin halides.     

Triorganotin(IV) Derivatives of Bidentate Schiff Bases: Synthesis and Spectral Studies

Abstract

Reaction of tri-n-butyl tin(IV) chloride with the sodium salt of Schiff bases [salicylidene-2-aminopyridine (sapH), salicylidene-2-amino-4-picoline (sapicH), salicylidene-2-methyl-1-aminobenzene (o-smabH), salicylidene-4-methyl-1-aminobenzene (p-smabH), salicylidene-1- aminobenzene (sabH), salicylidene-3-nitro-1-aminobenzene (snabH)] in MeOH-C₆H₆ mixture in 1:1 molar ratio produced complexes of the type [Buⁿ ₃Sn(sb)] (where sb = Schiff bases). All complexes obtained were characterized by elemental analysis (C, H, N, and Sn), infrared (IR), nuclear magnetic resonance (NMR; ¹H, ¹³C, and ¹¹⁹Sn), and TOF-MS spectroscopic studies. These complexes were found to be monomeric, colored viscous liquids and are soluble in polar solvents (methanol, ethanol, DMSO, and DMF). On the basis of ¹¹⁹Sn NMR observations, a five coordination geometry around tin(IV) atom in these complexes is proposed tentatively.