Electrochemical Synthesis and Characterization of Tin(IV) Complexes of Dianionic Terdentate Schiff Base Ligands

Tin(IV) complexes of the series of dianionic terdentate Schiff bases N‐[(2‐pyrroyl)methylidene]‐N′‐tosylbenzene‐1,2‐diamine, (H₂L¹), N‐[(2‐hydroxyphenyl)methylidene]‐N′‐tosylbenzene‐1,2‐diamine (H₂L²) and some R substituted 2‐{[(2‐hydroxyphenyl)imino]methyl}phenols [R = H (H₂L³), 4,6‐(OCH₃)₂ (H₂L⁴), 3‐(OC₂H₅) (H₂L⁵) and 3,5‐Br₂ (H₂L⁶)] have been synthesized. The compounds were obtained by the electrochemical oxidation of a tin anode in a cell containing an acetonitrile solution of the corresponding ligand. The complex [SnL¹₂] was also obtained by reaction of SnCl₂·2H₂O and H₂L¹ in methanol in the presence of triethylamine. The crystal structure of the ligand [H₂L⁶] and the complexes [SnL¹₂] (1) , [SnL²₂] (2) , [SnL³₂] (3) and [SnL⁶₂] (6) were determined by X‐ray diffraction. In the complexes, the tin atom is in an octahedral environment coordinated by two dianionic terdentate ligands. Spectroscopic data for the complexes (IR, ¹H and ¹¹⁹Sn NMR and mass spectra) are discussed and related to structural information.     

Synthesis,structural characterization and bioassay screening of dimeric bis[dicarboxylatotetraorganodistannoxanes]

Reaction of bis(pyrazol‐1‐yl)acetic acid with n‐Bu₂SnO in a 1:1 molar ratio gives dimeric bis[dicarboxylatotetraorganodistannoxanes], {[(n‐Bu)₂(Pz₂CHCO₂)Sn]₂O}₂ (Pz = pyrazol‐1‐yl or 3,5‐dimethylpyrazol‐1‐yl), which are characterized by IR and NMR (¹H, ¹³C and ¹¹⁹Sn) spectra and elemental analyses. The X‐ray crystal structure analyses indicate that {[(n‐Bu)₂(Pz₂CHCO₂)Sn]₂O}₂ is a centrosymmetric dimer with a cyclic Sn₂O₂ unit, in which each tin atom is situated in a distorted trigonal bipyramidal geometry. In addition, bis(3,5‐dimethylpyrazol‐1‐yl)acetic acid in the solid state forms a dimer through two intermolecular O? H···N hydrogen bonds. These organotin derivatives display low fungicide, insecticide and miticide activities, but display certain cytotoxicities for Hela cells in vitro. Copyright © 2005 John Wiley & Sons, Ltd.     

Self-assembly of diorganotin(IV) 2-{[(E)-1-(2-oxyaryl)alkylidene]amino}acetates: An investigation of structures by X-ray diffraction, solution and solid-state tin NMR, and electrospray ionization MS

The diorganotin(IV) compounds, [Me₂SnL²(OH₂)]₂ (1), [ⁿBu₂SnL²(OH₂)]₂ (2), [ⁿBu₂SnL¹]₃ · 0.5C₃H₆O (3), [ⁿBu₂SnL³]₃ · 0.5C₆H₆ (4) and [Ph₂SnL³]_n · 0.5C₆H₆ (5) (L = carboxylic acid residue, i.e., 2-{[(E)-1-(2-oxyaryl)alkylidene]amino}acetate), were synthesized by treating the appropriate diorganotin(IV) dichloride with the potassium salt of the ligand in anhydrous methanol.The reaction of Ph₂SnL² (L = 2-{[(E)-1-(2-oxyphenyl)ethylidene]amino}acetate) with 1,10-phenanthroline (Phen) yielded a 1:1 adduct of composition, [Ph₂SnL²(Phen)] (6).The crystal structures of 1-6 were determined.The crystal of 1 is composed of centrosymmetric dimers of the basic Me₂SnL²(OH₂) moiety, where the two Sn-centres are linked by two asymmetric Sn-O?Sn bridges involving the carboxylic acid O atom of the ligand and a long Sn?O distance of 3.174(2) Å.The dimers are further linked into columns by hydrogen bonds.The coordination geometry about the Sn atom is a distorted pentagonal bipyramid with the two methyl groups in axial positions.The structure of 2 is similar.The same Sn atom coordination geometry is observed in compound 3, which is a cyclic trinuclear[ⁿBu₂SnL¹]₃ compound. Each Sn atom is coordinated by the phenoxide O atom, one carboxylate O atom and the imino N atom from one ligand and both the exo- and endo-carboxylate O atoms (mean Sn-O(exo): 2.35 Å; Sn-O(endo): 2.96 Å) from an adjacent ligand to form the equatorial plane, while the two butyl groups occupy axial positions. Compound 4 was found to crystallize in two polymorphic forms. The Sn-complex in both forms has a trinuclear [ⁿBu₂SnL³]₃ structural motif similar to that found in 3. In compound 5, distorted trigonal bipyramidal Ph₂SnL³ units are linked into polymeric cis-bridged chains by a weak Sn?O interaction (3.491(2) Å) involving the exocyclic O atom of the tridentate ligand of a neighboring Sn-complex unit. This interaction completes a highly distorted octahedron about the Sn atom, where the weakly coordinated exocyclic O atom and one phenyl group are trans to one another. In contrast, a monomeric distorted pentagonal bipyramidal geometry is found for adduct 6 where the Sn-phenyl groups occupy the axial positions. The solution and solid-state structures are compared by using ¹¹⁹Sn NMR chemical shift data. Compounds 1-6 were also studied using ESI-MS and their positive- and negative-ions mass fragmentation patterns are discussed.     

Synthesis,Spectroscopic, and X‐Ray Diffraction Studies of cis‐Dichlorobis(4‐propanoyl‐2,4‐dihydro‐5‐methyl‐2‐phenyl3 H‐pyrazol‐3‐onato) Tin(IV)

Reaction between an aqueous ethanol solution of tin(II) chloride and that of 4‐propanoyl‐2,4‐dihydro‐5‐methyl‐2‐phenyl‐3 H‐pyrazol‐3‐one in the presence of O₂ gave the compound cis‐dichlorobis(4‐propanoyl‐2,4‐dihydro‐5‐methyl‐2‐phenyl‐3 H‐pyrazol‐3‐onato) tin(IV) [(C₂₆H₂₆N₄O₄)SnCl₂]. The compound has a six‐coordinated Sn^IV centre in a distorted octahedral configuration with two chloro ligands in cis position. The tin atom is also at a pseudo two‐fold axis of inversion for both the ligand anions and the two cis‐chloro ligands. The orange compound crystallizes in the triclinic space group P 1 with unit cell dimensions, a = 8.741(3) Å, b = 12.325(7) Å, c = 13.922(7) Å; α = 71.59(4), β = 79.39(3), γ = 75.18(4); Z = 2 and D_x = 1.575 g cm^–3. The important bond distances in the chelate ring are Sn–O [2.041 to 2.103 Å], Sn–Cl [2.347 to 2.351 Å], C–O [1.261 to 1.289 Å] and C–C [1.401 Å] the bond angles are O–Sn–O 82.6 to 87.7° and Cl–Sn–Cl 97.59°. The UV, IR, ¹H NMR and ¹¹⁹Sn Mössbauer spectral data of the compound are reported and discussed.     

Synthesis,spectroscopic characterization,and biological activity studies of organotin(IV) derivatives of (E)‐3‐(3‐fluorophenyl)‐2‐phenyl‐2‐propenoic acid. Crystal and molecular structure of Et2Sn[OCOC(C6H5)CH(3‐FC6H4)]

The complexes Me₂SnL₂ ( I ), Me₃SnL ( II ), Et₂SnL₂ ( III ), n‐Bu₂SnL₂ ( IV ), n‐Bu₃SnL ( V ), n‐Oct₂SnL₂ ( VI ), Bz₂SnL₂ ( VII ), and Ph₃SnL ( VIII ), where “L” is ( E )‐3‐(3‐fluorophenyl)‐2‐phenyl‐2‐propenoate, have been prepared and structurally characterized by means of elemental analysis, infrared, mass, and multinuclear (¹H, ¹³C, ¹¹⁹Sn) NMR spectral techniques. The spectroscopic results showed that the geometry around the Sn atom in triorganotin(IV) derivatives is four‐coordinated in noncoordinating solvent and behaves as five‐coordinated linear polymers with bridging carboxylate groups or five‐coordinated monomers, both acquiring trans‐R₃SnO₂ geometry for Sn in the solid state. While all the diorganotin(IV) derivatives may acquire trigonal bipyramidal structures in solution due to collapse of the Sn←OCO interaction and octahedral geometries in the solid state, which have been confirmed by the X‐ray crystallographic data of the compound III . The crystal structure of Et₂SnL₂ ( III ) has been determined by X‐ray crystallography and is found skew‐trapezoidal bipyramidal, which substantiates that the ligand acts as an anisobidentate chelating agent, thus rendering the Sn atom six coordinated. The crystal is monoclinic with space group C2₁/n. All the investigated compounds have also been screened for biocidal and cytotoxicity data. © 2006 Wiley Periodicals, Inc. Heteroatom Chem 17:420–432, 2006; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20243     

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.     

Organotin(IV) esters of (E)‐3‐furanyl‐2‐phenyl‐2‐propenoic acid: Synthesis,investigation of the coordination modes by IR,multinuclear NMR (1H, 13C, 119Sn) and In Vitro biological studies

Complexes [Me₂SnL₂ ( I ), Me₃SnL ( II ), Et₂SnL₂ ( III ), n‐Bu₂SnL₂ ( IV ), n‐Bu₃SnL ( V ), n‐Oct₂SnL₂ ( VI )], where L is (E)‐3‐furanyl‐2‐phenyl‐2‐propenoate, have been synthesized and structurally characterized by vibrational and NMR (¹H, ¹³C and ¹¹⁹Sn) spectroscopic techniques in combination with mass spectrometric and elemental analyses. The IR data indicate that in both the di‐ and triorganotin(IV) carboxylates the ligand moiety COO acts as a bidentate group in the solid state. The ¹¹⁹Sn NMR spectroscopic data, ¹J[¹¹⁹Sn,¹³C] and ²J[¹¹⁹Sn, ¹H], coupling constants show a four‐coordinated environment around the tin atom in triorganotin(IV) and five‐coordinated in diorganotin(IV) carboxylates in noncoordinating solvents. The complexes have been screened against bacteria, fungi, and brine‐shrimp larvae to assess their biological activity. © 2008 Wiley Periodicals, Inc. Heteroatom Chem 19:612–620, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20488     

Synthesis,characterization and biological activity of diphenyltin(IV) complexes of N‐(3,5‐dibromosalicylidene)‐α‐amino acid and their diphenyltin dichloride adducts

Diphenyltin(IV) complexes of N‐(3,5‐dibromosalicylidene)‐α‐amino acid, Ph₂Sn[3,5‐Br₂‐2‐OC₆H₂ CH?NCH(R)COO] (where R = H, Me, i‐Pr, Bz), and their 1:1 adducts with diphenyltin dichloride, Ph₂Sn[3,5‐Br₂‐2‐OC₆H₂CH?NCH(R)COO]·Ph₂SnCl₂, have been synthesized and characterized by elemental analysis, IR and NMR (¹H, ¹³C and ¹¹⁹Sn) spectra. The crystal structure of Ph₂Sn[3,5‐Br₂‐2‐OC₆H₂CH?NCH(i‐Pr)COO] shows a distorted trigonal bipyramidal geometry with the axial locations occupied by a carboxylate–oxygen and a phenolic–oxygen atom of the ligand, and that of Ph₂Sn[3,5‐Br₂‐2‐OC₆H₂CH?NCH(i‐Pr)COO]·Ph₂SnCl₂ reveals that the two tin atoms are joined via the carbonyl atom of the ligand to form a mixed organotin binuclear complex. Bioassay indicates that the compounds possess better cytotoxic activity against three human tumor cell lines (HeLa, CoLo205 and MCF‐7) than cis‐platin and moderate antibacterial activity against two bacteria (E. coli and S. aureus). Copyright © 2005 John Wiley & Sons, Ltd.     

Destruktive Komplexierung des dimeren Diorganylzinn(IV)‐hydroxids [Me2Sn(A)(μ‐OH)]2 (HA = Benzol‐1,2‐disulfonsäureimid): Bildung und Strukturen der Einkernkomplexe [Me2Sn(A)2(OPPh3)2] und [Me2Sn(phen)2]2⊕ · 2 A⊖ · MeCN

Polysulfonylamines. CXVI. Destructive Complexation of the Dimeric Diorganyltin(IV) Hydroxide [Me₂Sn(A)(μ‐OH)]₂ (HA = Benzene‐1,2‐disulfonimide): Formation and Structures of the Mononuclear Complexes [Me₂Sn(A)₂(OPPh₃)₂] and [Me₂Sn(phen)₂]^2⊕ · 2 A^⊖ · MeCN Destructive complexation of the dimeric hydroxide [Me₂Sn(A)(μ‐OH)]₂, where A^⊖ is deprotonated benzene‐1,2‐disulfonimide, with two equivalents of triphenylphosphine oxide or 1,10‐phenanthroline in hot MeCN produced, along with Me₂SnO and water, the novel coordination compounds [Me₂Sn(A)₂(OPPh₃)₂] ( 3 , triclinic, space group P 1) and [Me₂Sn(phen)₂]^2⊕ · 2 A^⊖ · MeCN ( 4 , monoclinic, P2₁/c). In the uncharged all‐trans octahedral complex 3 , the heteroligands are unidentally O‐bonded to the tin atom, which resides on a crystallographic centre of inversion [Sn–O(S) 227.4(2), Sn–O(P) 219.6(2) pm, cis‐angles in the range 87–93°; anionic ligand partially disordered over two equally populated sites for N, two S and non‐coordinating O atoms]. The cation occurring in the crystal of 4 has a severely distorted cis‐octahedral C₂N₄ coordination geometry around tin and represents the first authenticated example of a dicationic tin(IV) dichelate [R₂Sn(L–L′)₂]^2⊕ to adopt a cis‐structure [C–Sn–C 108.44(11)°]. The five‐membered chelate rings are nearly planar, with similar bite angles of the bidentate ligands, but unsymmetric Sn–N bond lengths, each of the longer bonds being trans to a methyl group [ring 1: N–Sn–N 71.24(7)°, Sn–N 226.81(19) and 237.5(2) pm; ring 2: 71.63(7)°, 228.0(2) and 232.20(19) pm]. In both structures, the bicyclic and effectively C_S symmetric A^⊖ ions have their five‐membered rings distorted into an envelope conformation, with N atoms displaced by 28–43 pm from the corresponding C₆S₂ mean plane.     

Synthesis and crystal structures of new complexes of di- and tribenzyltin 2-amino-1-cyclopentene-1-carbodithioates

Treatment of dibenzyltin dichloride with 1 equiv. of 2-amino-1-cyclopentene-1-carbodithioic acid (ACDA) gave Bz₂SnCl(ACDA) (1) that contains five coordinate tin. Reaction of 2 equiv. of ammonium 2-amino-1-cyclopentene-1-carbodithioic acid (AACD) with Bz₂SnCl₂ and then recrystallization from THF produced Bz₂Sn(ACDA)₂ · THF 2 in which the coordination geometry around the Sn is highly distorted from octahedral. Bz₃Sn(ACDA) (3) was obtained from reaction of Bz₃SnCl with 1 equiv. of AACD. The crystal structure of 3 indicates a Sn-S′ interaction [3.0823(5) Å] that distorts the tin coordination geometry from that of an ideal tetrahedron. In 1-3 the tin atom is also coordinated to one carbon atom of each benzyl group. The products were characterized by IR and NMR (¹H, ¹³C, ¹¹⁹Sn) spectroscopy and elemental analysis.     

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.     

Synthesis and characterization of dimeric organotin compounds {[(ArCH2)2 Sn(2‐quin)]2O}2 and crystal structure of {[(2‐ClC6 H4CH2)2Sn(2‐quin)]2O}2

Ten new dimeric organotin compounds {[(ArCH₂)₂ Sn(2‐quin)]₂O}₂ (Ar = Ph 1 , 2‐ClC₆H₄ 2 , 3‐ClC₆H₄ 3 , 4‐ClC₆H₄ 4 , 2‐FC₆H₄ 5 , 3‐FC₆H₄ 6 , 4‐FC₆H₄ 7 , 4‐BrC₆H₄ 8 , 4‐CNC₆H₄ 9 , 2,4‐Cl₂C₆H₃ 10 ) have been synthesized by dealkylation reactions of 2‐quinH with [(ArCH₂)₃Sn]₂O, and their structures have been characterized by elemental analysis, IR and NMR (¹}H, ¹³C, ¹¹⁹Sn) spectroscopies. The structures of {[(2‐ClC₆H₄CH₂)₂Sn(2‐quin)]₂O}₂ 2 have been determined by X‐ray diffraction. Studies show that compound 2 has a tetranuclear, centrosymmetric dimeric structure, with the endo‐cyclic tin atom five‐coordinated and the exo‐cyclic tin atom six coordinated. Studies also show that the nitrogen atoms of the 2‐quin ligand are coordinating to the tin atom for all the ten compounds. © 2006 Wiley Periodicals, Inc. Heteroatom Chem 17:152–159, 2006; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20194     

Synthesis,structure and cytotoxic activity of diethyltin N‐[(2‐oxyphenyl)methylene]phenylalaninates

Four new diethyltin N‐[(2‐oxyphenyl)methylene]phenylalaninates, (CH₃CH₂)₂Sn[2‐O‐3‐X‐5‐YC₆H₂CH?NCH(CH₂Ph)COO] (X, Y = H, H, 1 ; H, Br, 2 ; H, OCH₃, 3 ; Br, Br, 4 ), have been synthesized and characterized using elemental analysis and infrared and NMR (¹H, ¹³C and ¹¹⁹Sn) spectra. The crystal structures of 1 , 2 , 3 , 4 have been determined. Compounds 1 and 2 have a 12‐membered macrocyclic structure with a trimeric [Sn₃O₆C₃] core. Each tin atom is six‐coordinated in distorted [SnC₂NO₃] octahedral geometry. Compound 3 is a centrosymmetric weak dimer in which the two tin centers are linked by two asymmetric Sn? O???Sn bridges involving the phenolic oxygen of the ligand and two Sn???O interactions from ether oxygen of the adjacent ligand. The coordination geometry of the tin atom can be described as a distorted pentagonal bipyramid with two ethyl groups in axial positions. Compound 4 is a novel binuclear tin complex, formed by the carboxylate of a ligand asymmetrically bridging two tin atoms, which contains a five‐coordinated tin and a six‐coordinated tin. Bioassay results have shown that the compounds have weak in vitro activity against two human tumor cell lines, A549 and CoLo205. Copyright © 2016 John Wiley & Sons, Ltd.     

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.     

Organotin Carboxylates based on 3‐(1,3‐Dioxo‐2,3‐dihydro‐1H‐phenalen‐2‐yl)benzoic Acid and the Influence of Solvent on the Molecular Structure

Self‐assembly of dibutyltin oxide with 3‐(1,3‐dioxo‐2,3‐dihydro‐1H‐phenalen‐2‐yl)benzoic acid (HL) produces (nBu)₂SnL₂ ( 1 ) when benzene is used as solvent, whereas the reaction generates {[(nBu)₂SnO]₂L}₂ · C₇H₈ ( 2 ) when toluene is the reactive solvent. The novel organotin carboxylate (nBu)₂SnL₂ ( 1 ) was characterized by elemental analysis, as well as IR, ¹H, ¹³C, and ¹¹⁹Sn NMR spectroscopy. Single crystal X‐ray study reveals that 1 is a dialkyltin carboxylate monomer possessing crystallographically imposed twofold symmetry. Ligand HL in 1 chelates with tin atom in bidentate coordination mode. The molecules of 1 build complicate 1D, 2D, and 3D structures via intermolecular hydrogen bonds, and π ··· π interactions can be found in the 3D architecture. The preliminary fluorescence activity and antitumor activity of the complex were also studied.     

Synthesis,structural characterization and antimicrobial activity of mixed aryl–alkyl diorganotin(IV) compounds with quinoline‐2‐carboxylate (L−): {RR′SnLCl}n and RR′SnL2

A series of unsymmetrical diorganotin derivatives of quinoline‐2‐carboxylic acid (LH), namely polymeric {MePhSnClL}_n (1) and {EtPhSnClL}_n (2), and mononuclear MePhSnL₂ (3) and EtPhSnL₂ (4), was synthesized by the reaction of LH with the MePhSnCl₂, EtPhSnCl₂, MePhSnO, and EtPhSnO precursors, respectively. The compounds were characterized by elemental analysis and infrared spectroscopy, as well as by ¹ H, ¹³ C and ¹¹⁹Sn NMR. The molecular structures of representative compounds 2 and 4 were determined by single‐crystal X‐ray crystallography. This study showed that polymeric 2 adopts a distorted octahedral geometry as the carboxylate ligand N,O chelates an Sn atom and at the same time bridges a neighbouring Sn atom via the second O atom, with the remaining sites being occupied by the Cl and two C atoms; the O atoms are trans to each other. The result of the μ₂‐bridging mode of L^? is the formation of a supramolecular helical chain. Compound 4 adopts a skew‐trapezoidal bipyramidal geometry with the organo groups lying over the plane of the two N,O‐chelating carboxylate ligands and being directed over the weaker Sn―N bonds. The in vitro antimicrobial activities of 1–4 against a Gram‐positive bacteria strain (Bacillus subtilis), a Gram‐negative bacteria strain (Escherichia coli) and against Candida albicans were studied and compared with the antimicrobial activities of Ph₂SnL₂ and Me₂SnL₂, and with the antimicrobial standards gentamicin, tetracycline, ampicillin and penicillin. All organotin compounds displayed remarkable antibacterial activities that were comparable to those of the standard drugs, in particular against B. subtilis, where the activity was correlated with the number of Cl substituents. Copyright © 2012 John Wiley & Sons, Ltd.     

Structural diversity of organotin(IV) complexes self-assembled from hydroxamic acid and mono- or dialkyltin salts

Three hydroxamic acid ligands (HL₁ = acetohydroxamic acid; HL₂ = benzohydroxamic acid; HL₃ = N-phenylbenzohydroxamic acid), have been used to synthesize series of mono- or dialkyltin(IV) complexes, which include (i) the carboxyl acid hybrid five-coordinated dialkyltin complexes (C₄H₉)₂SnL₁L₄ (1), [(CH₃)₂SnL₂L₅]·0.5C₆H₆ (2), (HL₄ = acetic acid; HL₅ = benzoic acid); (ii) the six-coordinated mono-n-butyltin complexes (C₄H₉)SnL₁·Cl₂·H₂O (3), (C₄H₉)SnL₂·Cl₂·H₂O (4), [(C₄H₉)SnL₃·Cl₂·H₂O]·H₂O (5), [(C₄H₉Sn)₂(L₃)₂·Cl₂·(OCH₃)₂] (6); and (iii) the alkali metal-mingled seven-coordinated mono-n-butyltin complexes [(C₄H₉Sn)₃L₂Na]⁺·Cl⁻·(CH₃CH₂)₂O (7), [(C₄H₉Sn)₃L₂K]⁺·Cl⁻·CH₂Cl₂ (8). All complexes were characterized by elemental analyses, IR, ¹H, ¹³C, ¹¹⁹Sn NMR and X-ray single crystal diffraction. In these complexes, hydroxamic acids present bidentate coordination modes with the carbonyl O atom and the hydroxyl O atom binding to tin center. In complexes 1-6, each tin atom is coordinated by one hydroxamic acid ligand. However, in complexes 7 and 8, tin atom is surrounded by three hydroxamic acid ligands, and all hydroxyl O atoms of the ligands also bind to the alkali metal center (Na or K). This kind of organotin(IV) framework containing one alkali metal is found for the first time. Furthermore, the supramolecular structures of 1, 3, 4 and 6 have been found to consist of 1D linear molecular chains formed by intermolecular N-H···X or C-H···X (X = O, N or Cl) hydrogen bonds. For complex 2, an interesting macrocyclic tetramer has been built by the intermolecular N-H···O hydrogen bonds. Fascinatingly, two unique symmetric dimeric structures are recognized in complexes 7 and 8, which is individually bridged by intermolecular N-H···Cl and N-H···O hydrogen bonds. In addition, for 8, the dimeric cycles have been further connected into a 1D supramolecular chain.     

3‐(Pyridin‐4‐yl)acetylacetone: CdII and HgII compete for nitrogen coordination

3‐(Pyridin‐4‐yl)acetylacetone (HacacPy) acts as a pyridine‐type ligand towards Cd^II and Hg^II halides. With CdBr₂, the one‐dimensional polymer [Cd(μ‐Br)₂(HacacPy)Cd(μ‐Br)₂(HacacPy)₂]_∞ is obtained in which five‐ and six‐coordinated Cd^II cations alternate in the chain direction. Reaction of HacacPy with HgBr₂ results in [Hg(μ‐Br)Br(HacacPy)]_∞, a polymer in which each Hg^II centre is tetracoordinated. In both compounds, each metal(II) cation is N‐coordinated by at least one HacacPy ligand. Equimolar reaction between these Cd^II and Hg^II derivatives, either conducted in ethanol as solvent or via grinding in the solid state, leads to ligand redistribution and the formation of the well‐ordered bimetallic polymer catena‐poly[[bromidomercury(II)]‐μ‐bromido‐[aquabis[4‐hydroxy‐3‐(pyridin‐4‐yl)pent‐3‐en‐2‐one]cadmium(II)]‐di‐μ‐bromido], [CdHgBr₄(C₁₀H₁₁NO₂)₂(H₂O)]_n or [{HgBr}(μ‐Br){(HacacPy)₂Cd(H₂O)}(μ‐Br)₂]_∞. Hg^II and Cd^II cations alternate in the [100] direction. The HacacPy ligands do not bind to the Hg^II cations, which are tetracoordinated by three bridging and one terminal bromide ligand. The Cd^II centres adopt an only slightly distorted octahedral coordination. Three bromide ligands link them in a (2 + 1) pattern to neighbouring Hg^II atoms; two HacacPy ligands in a cis configuration, acting as N‐atom donors, and a terminal aqua ligand complete the coordination sphere. Classical O—H…Br hydrogen bonds stabilize the polymeric chain. O—H…O hydrogen bonds between aqua H atoms and the uncoordinated carbonyl group of an HacacPy ligand in a neighbouring strand in the c direction link the chains into layers in the (010) plane.     

Self-assembly of extended Schiff base amino acetate skeletons, 2-{[(2Z)-(3-hydroxy-1-methyl-2-butenylidene)]amino}phenylpropionate and 2-{[(E)-1-(2-hydroxyaryl)alkylidene]amino}phenylpropionate skeletons incorporating organotin(IV) moieties: Synthesis,spectroscopic characterization,crystal structures,and in vitro cytotoxic activity

The organotin(IV) compounds, [Ph₃SnL¹H]_n · nCCl₄ (1), [Me₂SnL²(OH₂)] (2), [ⁿBu₂SnL²] (3), [Ph₂SnL²]_n (4), [Ph₃SnL²H]_n (5) and [Ph₃SnL³H]_n (7) (L¹ = 2-{[(2Z)-(3-hydroxy-1-methyl-2-butenylidene)]amino}phenylpropionate and L²⁻³ = 2-{[(E)-1-(2-hydroxyaryl)alkylidene]amino}phenylpropionate), were synthesized by treating the appropriate organotin(IV) chloride(s) with the potassium salt of the ligand in a suitable solvent, while [ⁿBu₂SnL³(OH₂)] (6) was obtained by reacting the acid form of L³ (generated in situ) with ⁿBu₂SnO. These complexes have been characterized by ¹H, ¹³C, ¹¹⁹Sn NMR, ESI-MS, IR and ^119mSn Mössbauer spectroscopic techniques in combination with elemental analyses. The crystal structures of 1 and 4–7 were determined. The crystal structures of complexes 1, 5 and 7 reveal that the complexes exist as polymeric chains in which the L-bridged Sn-atoms adopt a trans-R₃SnO₂ trigonal bipyramidal configuration with R groups in the equatorial positions and the axial locations occupied by a carboxylate oxygen from the carboxylate ligand and the alcoholic or phenolic oxygen of the next carboxylate ligand in the chain. The carboxylate ligands coordinate in the zwitterionic form with the alcoholic/phenolic proton moved to the nearby nitrogen atom. A polymeric zig-zag cis-bridged chain structure is observed for 4, without considering the weak Sn⋯O interaction, the Sn-atom having a slightly distorted trigonal bipyramidal coordination geometry with the two O atoms of the tridentate amino propionate ligand in axial positions. On the other hand, the structure of 6 reveals a monomeric molecule in which the Sn-atom has a distorted octahedral coordination geometry involving the tridentate carboxylate ligand, two n-butyl ligands occupying trans-positions and one water ligand. The in vitro cytotoxic activity of triphenyltin(IV) compounds, viz., 1, 5 and 7 against WIDR, M19 MEL, A498, IGROV, H226, MCF7 and EVSA-T human tumor cell lines are also reported.     

Disentangling steric and electronic factors in monomeric bis(2‐bromo‐4‐chloro‐6‐{[(2‐hydroxyethyl)imino]methyl}phenolato‐κ2N,O)copper(II)

The title compound, [Cu(C₉H₈BrClNO₂)₂], is a square‐planar complex. The potentially tridentate dibasic 2‐bromo‐4‐chloro‐6‐{[(2‐hydroxyethyl)imino]methyl}phenolate ligand coordinates in a trans‐bis fashion to the Cu^II centre via the imine N and phenolate O atoms. The Cu^II atom lies on the centre of inversion of the molecule. The potentially coordinating hydroxyethyl group remains protonated and uncoordinated, taking part in intermolecular hydrogen bonds with vicinal groups, leading to the formation of a two‐dimensional hydrogen‐bond network with sheets parallel to the (10) plane. Substituent effects on the crystal packing and coordination modes of the ligand are discussed.