Spectroscopic characterization and biological activity of L‐methionyl‐L histidinato complexes of R2Sn(IV) ions (R = Me,nBu, Ph) and X‐ray structure of Me2SnMetHis ˙ 0.5MeOH

Complexes of L ‐methionyl‐L ‐histidine (H₂MetHis) with R₂Sn(IV) ions (R = Me, nBu, Ph) have been synthesized. The crystal and molecular structures of Me₂SnMetHis·0.5MeOH have been determined by X‐ray diffraction. The title compound contains two crystallographically independent molecular units possessing the same trigonal‐bipyramidal geometry at tin, each dimethyltin(IV) moiety being coordinated by the terminal amino nitrogen, deprotonated peptide nitrogen and terminal carboxylate group, neither the imidazole nor thioether groups being involved in bonding. IR spectroscopy was used to probe the structure of the complexes in the solid state, and the structure in solution (CD₃OD) was assessed by ¹H and ¹³C NMR. Me₂Sn(IV)dipeptide complexes appear to be undissociated and to retain a pentacoordinated structure. Rotamer population of C‐terminal histidine was determined by analysis of vicinal coupling constants and side‐chain orientations have been interpreted with a view to potential applications of the compounds as recognition agents. Biological activity was tested on Ascidian embryos of Ciona intestinalis at different stages of development. Copyright © 2000 John Wiley & Sons, Ltd.     

Spectral characterization and biocidal activity of organotin(IV) (E)-3-[(2′,6′-dichlorophenylamido)]propenoates

Biocidal and spectroscopic aspects of organotin(IV) complexes with (E)-3-[(2′,6′-dichlorophenylamido)]propenoic acid are described with support of elemental analysis. IR, ¹H, ¹³C, ¹¹⁹Sn NMR and mass spectral data suggest that the ligand is bidentate, coordinating through oxygen atoms and that diorganotin(IV) complexes are six-coordinate. Triorganotin(IV) carboxylates exist as pentacoordinated trigonal bipyramidal complexes in the solid state and tetrahedral ones in solution. The complexes have been screened against bacteria, fungi and brine-shrimp larvae to assess their biological activity.     

Synthesis of tetravalent metal antimonates: Characteristics and use in treatment of radioactive waste solutions

Eight di-n-butyltin(IV) complexes with glycolic, 2-hydroxy-propionic, succinic and malic acids, have been prepared by two different procedures. The compounds were characterised by elemental analysis, FTIR, Raman and¹¹⁹Sn Mössbauer spectroscopy. The IR and Raman data indicated the presence of bidentate and/or monodentate carboxylate groups, non linear C?Sn?C bonds, and Sn?O bonds within the complexes. The results of Mössbauer spectroscopic measurements, based on point-charge model calculations, have shown the occurrence of trigonal bipyramidal environment in the central tin(IV) atom, besides the octahedral and tetrahedral structure.     

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.     

Synthesis,structural characterization and in vitro cytotoxic activity of novel polymeric triorganotin(IV) complexes of urocanic acid

Two novel triorganotin carboxylate complexes of the biologically active urocanic acid have been synthesized and characterized. Elemental analysis, melting point, spectroscopic techniques – IR, ¹H, ¹³C and ¹¹⁹Sn NMR – mass spectrometry and X‐ray diffraction studies have been used for structural characterization. Crystal structures of the tin(IV) derivatives show that urocanic acid acts as a bridging bidentate ligand through its imidazole nitrogen atom and its carboxylic group, producing a polymeric one‐dimensional chain. The molecular structures of the complexes, catena‐poly‐tri(n‐butyl)tin(IV) 3‐(3H‐imidazol‐4‐yl)prop‐2‐enoate (1) and catena‐poly‐triphenyltin(IV) 3‐(3H‐imidazol‐4‐yl)prop‐2‐enoate (2), present a distorted trigonal–bipyramidal configuration. This is further confirmed by ¹¹⁹Sn NMR in the solid state. The tin(IV) derivatives form double‐stranded ribbons via N―H^…O―H bonds. Nevertheless, the compounds are essentially monomeric in solution, with a tetrahedral configuration as observed by ¹¹⁹Sn NMR in solution. The cytotoxic activity of the titled compounds has been tested against six human cell lines and the corresponding IC₅₀ values are reported. Both tin(IV) compounds have a high to very high in vitro cytotoxic activity against the tumor cell lines K562, HCT‐15 and MCF‐7. Compound 1 is 86 times more active than cisplatin in the HTC‐15 cell line. Copyright © 2012 John Wiley & Sons, Ltd.     

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     

Multinuclear magnetic resonance and related studies on some organotin(IV) complexes of dithiocarbazates

Synthesis, characterization and geometrical features of pentacoordinated dibutyltin(IV) dithiocarbazate complexes of the type n-Bu₂Sn L (where L = dianion of $\text{S}$-methyl-B-N (2-hydroxy-phenyl) methylene and methyl dithiocarbazate are described. These are obtained as viscous oils from the reactions of n-Bu₂SnO with equimolar proportions of the ligands in benzene. On the basis of UV, IR, NMR (¹H, ¹³C, ¹¹⁹Sn) spectra along with the mass spectral fragmentation pattern a trigonal bipyramidal geometry is proposed. The N atom probably occupies the axial site, while the remaining two donor atoms O and S and the dibutyl groups rest in an equatorial plane. These complexes are active against P.388 Lymphocyte leukaemia system.     

Synthesis and characterization of di‐n‐butyltin(IV) complexes with 4′/2′‐nitrobiphenyl‐2‐carboxylic acids: X‐ray crystal structures of [{(n‐C4H9)2Sn(OCOC12H8NO2−4′)}2O]2 and (n‐C4H9)2Sn{OCOC12H8NO2−4′}2

Reactions of di‐n‐butyltin(IV) oxide with 4′/2′‐nitrobiphenyl‐2‐carboxylic acids in 1 : 1 and 1 : 2 stoichiometry yield complexes [{(n‐C₄H₉)₂Sn(OCOC₁₂H₈NO₂?4′/2′)}₂O]₂ ( 1 and 2 ) and (n‐C₄H₉)₂Sn(OCOC₁₂H₈NO₂?4′/2′)₂ ( 3 and 4 ) respectively. These compounds were characterized by elemental analysis, IR and NMR (¹H, ¹³C and ¹¹⁹Sn) spectroscopy. The IR spectra of these compounds indicate the presence of anisobidentate carboxylate groups and non‐linear C? Sn? C bonds. From the chemical shifts δ (¹¹⁹Sn) and the coupling constants ¹J(¹³C, ¹¹⁹Sn), the coordination number of the tin atom and the geometry of its coordination sphere have been suggested. [{(n‐C₄H₉)₂Sn(OCOC₁₂H₈NO₂?4′)}₂O]₂ ( 1 ) exhibits a dimeric structure containing distannoxane units with two types of tin atom with essentially identical geometry. To a first approximation, the tin atoms appear to be pentacoordinated with distorted trigonal bipyramidal geometry. However, each type of tin atom is further subjected to a sixth weaker interaction and may be described as having a capped trigonal bipyramidal structure. The diffraction study of the complex (n‐C₄H₉)₂Sn(OCOC₁₂H₈NO₂?4′)₂ ( 3 ) shows a six–coordinate tin in a distorted octahedral frame containing bidentate asymmetric chelating carboxylate groups, with the n‐Bu groups trans to each other. The n‐Bu? Sn? n‐Bu angle is 152.8° and the Sn? O distances are 2.108(4) and 2.493(5) Å. The oxygen atom of the nitro group of the ligand does not participate in bonding to the tin atom in 1 and 3 . Crystals of 1 are triclinic with space group P1 and of that of 3 have orthorhombic space group Pnna. Copyright © 2003 John Wiley & Sons, Ltd.     

Organometallic complexes with biological molecules. I. Diorganotin(IV)chloro protoporphyrin IX complexes: Solid-state and solution-phase characterization

Protoporphyrin IX (H₄PPIX) complexes of diorganotin(IV)chloro moieties with formula (R₂SnCl)₂H₂PPIX (R?Me, Bu and Ph) have been obtained and their solid-state and solution-phase configurations have been studied through spectroscopic investigations. Coordination of the side-chain carboxylates of H₄PPIX to R₂Sn(IV)Cl moieties, with bridging carboxylate (COO^?) has been inferred by comparison of the free and coordinated H₄PPIX IR spectra, while the occurrence of a five-coordinated tin(IV) atom in a cis-R₂ trigonal bipyramidal structure has been deduced, for all of the synthesized complexes, by rationalization of the nuclear quadrupole splitting parameters, according to the point-charge model formalism. Fanally, the solution-phase spectral features of (R₂SnCl)₂^?H₂PPIX are in agreement with the monomeric character of the protoporphyrin IX, under the experimental conditions used.     

New diorganotin(IV) complexes of Schiff base derived from 4‐amino‐3‐hydrazino‐5‐mercapto‐4H‐1,2,4‐triazole: Synthesis,structural characterization,density functional theory studies,atoms‐in‐molecules analysis and antifungal activity

New diorganotin(IV) complexes of a Schiff base (HL) having general formula R₂Sn(L)Cl (where L is the monoanion of HL and R = n‐Bu or Ph) have been synthesized and characterized using elemental analysis, infrared, NMR (¹H, ¹³C, ¹¹⁹Sn) and UV–visible spectroscopies and mass spectrometry. These investigations suggest that in these 1:1 monomeric derivatives the Schiff base ligand acts in a monoanionic bidentate manner coordinating through the O_phenolic and N_azomethine, with proposed distorted trigonal bipyramidal geometry around tin with O_phenolic and two organic groups in the equatorial plane and the N_azomethine and the third organic group in axial positions. The proposed structures have been validated by density functional theory (DFT)‐based quantum chemical calculations at the B3LYP/6‐31G(d,p)/Def2‐SVP (Sn) level of theory. The simulated UV–visible spectrum was obtained with the time‐dependent DFT method in the gas phase and in the solvent field with the integral equation formalism–polarizable continuum model. A comparative analysis of the experimental vibrational frequencies and simulated harmonic frequencies indicates a good correlation between them. An insight into the intramolecular bonding and interactions among bonds in organotin(IV) complexes of HL was obtained by means of natural bond orbital analysis. The topological and energetic properties of the electron density distribution for the tin–ligand interaction in R₂Sn(L)Cl have been theoretically calculated at the bonds around the central tin atom in terms of atoms‐in‐molecules theory. The R₂Sn(L)Cl complexes were screened for their in vitro antifungal activity against chosen fungal strains.     

Synthesis and <Emphasis Type="Italic">in vitro</Emphasis> Fungicidal Study of Organotin(IV) Complexes of Monomethyl Glutarate

The synthesis and study of new coordination compounds of some organotin(IV) chlorides with monomethyl glutarate are reported. The ligand molecule appears to be bound to the tin atom through the carboxylic oxygen. The results obtained from ¹H, ¹³C, and ¹¹⁹Sn NMR, FT-IR and ¹¹⁹Sn Mossbauer spectra show that the complexes are pentacoordinated with the trigonal bipyramidal structure. Biological screening of organotin(IV) derivatives shows promising activity, especially for the triphenyltin complex exhibiting higher antifungal activity. In addition, the rest of the compounds also prove to be active against various fungi used.     

Triorganotin derivatives of 1,2-BIS(2′-carboxyphenylamino)-ethane and -propane,and ethylenediaminetetraacetic acid

Fifteen new complexes have been prepared of the type (R₃Sn)₂ L, where L is the dianion of 1,2-bis(2′-carboxyphenylamino)-ethane-and -propane, and ethylenediaminetetraacetic acid, and R is Me, n-Pr, n-Bu, Ph, or cyclohexyl (Cy). Characterisation by IR, ¹H NMR and ¹¹⁹Sn Mössbauer spectroscopy indicates that the ligands are bound only through oxgen. In most cases the carboxylates are bidentate and the tin five-coordinate. The Ph₃Sn and Cy₃Sn derivatives contain tetrahedral tin, with monodentate carboxylates.     

A Novel Tetranuclear Organotin(IV) Carboxylate with Chain Structure: Synthesis,Crystal Structure,and Characterizations

A new tetranuclear organotin carboxylate {[(n‐Bu₂SnO)₂L]₂}_n (complex 1 ) was synthesized by the reaction of di‐n‐butyltin oxide with (p‐carboxymethoxy‐phenoxy) acetic acid (LH₂) and characterized by elemental analyses: IR, UV–visible, ¹H, ¹³C, ¹¹⁹Sn NMR spectroscopy and single crystal X‐ray study. X‐ray crystallography diffraction data revealed that the complex 1 was polymeric fashion with a chain structure containing a ladder‐like tetranuclear organo‐oxotin cluster. In the complex 1 , the ligand LH₂ is coordinated to the central tin(IV) atoms via the carboxylato‐O atoms. The tetranuclear tin system is formed by the bridges through the carbonyl oxygen atom of the carboxylate moieties and making the tin atom of pentacoordinated in distorted trigonal bipyramidal geometry. Single crystal X‐ray data indicate that the complex 1 crystallized in the cubic system with the space group C₂/c.     

Multinuclear (Sn/Pd) complexes with disodium 2,2′-(dithiocarboxyazanediyl)diacetate hydrate; Synthesis,characterization and biological activities

Bimetallic chlorodi-/triorganotin(IV) derivatives of general formulas R₂(H₂O)SnLCSSSn(Cl)R₂ (R=Me: 1; Ph: 2) and R₃Sn(Na)LCSSSnR₃·H₂O (R=Bu: 3; Ph: 4) were prepared by reaction of iminodiacetic acid disodium salt hydrate (Na₂LH) with CS₂ and R₂SnCl₂/R₃SnCl in methanol. The reaction between Na₂LH, CS₂, and PdCl₂ produced [Na₂LCSS]₂Pd·2H₂O (5) which was treated with R₃SnCl to synthesize the heterobimetallic derivatives [R₃Sn(Na)LCSS]₂Pd·2H₂O (R=Me: 6; Ph: 7). The complexes were characterized by microanalysis, spectroscopic, and thermogravimetric analyses. Elemental analysis data, mass fragmentation, and thermal degradation patterns supported the molecular composition of the complexes. FT-IR data indicated monodentate binding of carboxylate while a chelating coordination mode of the dithiocarboxylate was verified in the solid state. A five-coordinate tin(IV) was demonstrated in the solid state. In solution, a tetrahedral/trigonal bipyramidal configuration around Sn(IV) and a square planar geometry of Pd(II) was indicated by multinuclear NMR (¹H and ¹³C) and UV-visible studies. The Pd(II) derivatives showed interaction with salmon sperm-DNA and caused an inhibition of alkaline phosphatase (ALPs). The antibacterial/antifungal potential of the coordination products varied with the nature of incorporated metal and a substitution pattern at tin(IV); the palladium metallation decreased the antimicrobial activities. The triorganotin(IV) products exhibited more powerful action against bacteria/fungi as compared to their diorganotin(IV) counterparts. The complexes displayed sufficiently lower hemolytic effects in vitro as compared to triton X-100 and slightly higher than PBS.     

Biologically potent organotin(IV) complexes of 2-maleimidoacetic acid

The in vitro LD₅₀, anti-bacterial, anti-fungal and anti-yeast bio-tests are carried out, which proved them to be powerful biocides. The in vitro anti-tumour and analgesic activities also displayed excellent potential of the title compounds. Series of organotin(IV) complexes are synthesized and characterized. Based on spectroscopic analysis and literature evidences, the compound 1 is tetrahedral and 2 distorted octahedral or trigonal bipyramidal in nature wherein the compounds 3 and 4 are tetrahedral in solid and polymeric trigonal bipyramidal geometry in solution. Beside to ¹H, ¹³C and ¹¹⁹Sn NMR, the FT-IR is successfully applied to verify the bonding mode of endo and exo status of tin(IV) of compound 2.     

Synthesis,spectroscopic and structural characterization of diphenyltin(IV) complexes of acetone Schiff bases of S-alkyldithiocarbazates

New diphenyltin(IV) complexes of empirical formula, [Sn(C₆H₅)₂(NS)Cl] (NS = anionic forms of the acetone Schiff bases of S-methyl or S-benzyldithiocarbazate) have been prepared and characterized by IR, NMR and Mössbauer spectroscopic techniques. The crystal and molecular structures of the acetone Schiff bases of S-methyldithiocarbazate (Hacsme) and S-benzyldithiocarbazate (Hacsbz) and their tin(IV) complexes have been determined by X-ray diffraction. In the solid state, both the Schiff bases exist in their thioketo tautomeric forms with the azomethine nitrogen atom trans to the thione sulfur atom but in the tin(IV) complexes they are present in their deprotonated ene-thiolate forms being coordinated to the tin atom as bidentate chelating agents via the azomethine nitrogen and thiolate sulfur atoms. The tin atom adopts a five-coordinate, approximately trigonal bipyramidal geometry, with the thiolate sulfur atom of the Schiff base and the two phenyl groups occupying the equatorial positions. The azomethine nitrogen atom and the chlorine ligand occupy axial positions. The distortion from a regular trigonal bipyramidal or a square-pyramidal geometry is attributed to the restricted bite sizes of the five-membered chelate rings.     

Diorganotin(IV) complexes of indole 3-acetic acid

Alkyl derivatives of indole 3-acetic acid (IAA) have been prepared and are suitable for investigating steric substituent effects on hormonal activity without major interference from electronic effects. Triorganotin(IV) derivatives of indole 3-acetic acid and N-methylindole 3-acetic acid have been reported to act as insecticidal, fungicidal and bactericidal agents. Me₃SnIAA is more active as a biocide than Cy₃SnIAA. The activity of these two compounds may be due to the fact that four-coordinated tin monomers or five-coordinated tin polymers are often more active than chelated five-coordinated tin species because these readily undergo hydrolysis to give R₃Sn(H₂O⁺)₂ species. The ligand affects the rate of formation of the ligand-free active organotin entity. Biocidal activity is expected from diorganotin(IV) pentacoordinated complexes of indole 3-acetic acid in the present case due to (i) the activity of pentacoordinated organotin species, (ii) the presence of an—NH moiety in the complexes, which is an active site for binding. The NH moiety may be deprotonated and nitrogen may coordinate with metal ions present in the physiological systems and thus destroy the activity of enzymes.     

Triorganotin(IV) benzoates and aminobenzoates

Complexes of the general formula R₃SnX, where X is the anion of benzoic acid, o-, m-, p-amino- or N-phenyl-o-amino-benzoic acid, have been prepared and characterised. A combination of molecular weight, infrared, ¹H NMR and ¹¹⁹Sn Mössbauer measurements show that, the amino-nitrogen atoms are not coordinated to tin. When R = phenyl or cyclohexyl, the compounds are monomeric and four-coordinate, and when R is alkyl (Me, Prⁿ, Buⁿ) they are monomeric and five-coordinate, with a bidentate carboxylate in the equatorial position of a trigonal bipyramidal structure.     

Structural features of some organotin(IV) complexes of semi- and thio-semicarbazones

Some five- and six-coordinated di and tri-n-butyl tin(IV) semi- and thio-semi carbazates have been synthesized. The characterization of these complexes, by IR, NMR (¹H, ¹³C, ¹¹⁹Sn), ¹¹⁹Sn), ¹¹⁹Sn Mössbauer and Mass spectroscopies along with X-ray diffraction, reveals that complexes of biionic ligands of the type Bu₂Sn L″ are five-coordinated having trigonal bipyramidal geometry. However, complexes of monoionic ligands of the type Bu₂SnL′₂ are six-coordinated in a distorted cis-octahedral geometry and Bu₃SnL′ are five-coordinated with a trigonal bipyramidal structure. X-ray structural studies on the compound Bu₂Sn(O.C₆H₄.CH:N.N.CS.NH₂), show that it crystallizes in a monoclinic lattice with a = 16.90 Å, b = 9.71 Å, c = 8.60 Å, and β = 103°45′.