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Chelate Ring (chelate + ring)

Distribution by Scientific Domains
Chemistry96%
Distribution within Chemistry
General & Introductory Chemistry7%

Kinds of Chelate Ring

  • five-membered chelate ring
    		•
  • four-membered chelate ring
    		•
  • six-membered chelate ring
    		•

    Selected Abstracts

    Copper(I)-Assembled Pseudorotaxanes Bearing Bis(nitrile) Ligands: Selective Formation of Large Chelate Rings

    EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 3 2004
    Efstathia G. Sakellariou
    Abstract The syntheses of two novel CuI -bis(benzonitrile) complexes of the type [Cu(dCNn)2][PF6] {where dCNn = NCPhO(CH2)nOPhCN, n = 3, 4} are described. Both compounds have been characterized by X-ray crystallography. To our surprise, and although the two complexes were quite similar, two very distinct structures were obtained. For the [Cu(dCN4)2][PF6] complex, a tetrahedral geometry was observed whereas for [Cu(dCN3)2][PF6], a polymeric assembly was formed. A further extension of this work involved the syntheses of two threaded species bearing the M30 macrocycle, Cu metal and a dCNn ligand. The formation of the desired complexes was confirmed by means of mass spectrometry as well as 1-D and 2-D 1H NMR spectroscopy. Finally, the cyclic voltammograms of all 4 new species were recorded giving rise to redox potentials ranging from +0.88 to +1.25 V. These new threaded complexes are of particular interest since they can form the basis of novel rotaxane structures. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source]

    Crystal structure of a ternary mononuclear copper (II) complex: 4-chloro-3-methyl-6[(N-2-picolyl)-1,-iminomethyl]phenolato copper(II)perchlorate

    CRYSTAL RESEARCH AND TECHNOLOGY, Issue 5 2006
    S. M. Malathy Sony
    Abstract The complex crystallizes in monoclinic space group P21/n with unit cell parameters a = 7.295(4), b = 19.627(5), c = 12.770(4) Å, , = 101.25(4)º, V = 1793.2(12) Å3, Z = 4, , = 1.684 Mg/m3 at T = 293(2)K. The structure was solved by Patterson method and refined by full-matrix least-squares procedures to final R = 0.0387 using 2906 observed reflections. The asymmetric unit of the complex contains a mononuclear tridentate ligand, a perchlorate group and a methanol molecule. The compound crystallizes as parallel layers of polymeric complex bridged through perchloarate groups. The molecular CuN2OO,O,,2 chromophore involves an elongated rhombic octahedral structure and the Cu-ligand bond shows greater disparity. The five-membered chelate ring and the pyridine ring lie in the same plane while the six membered chelate ring assumes sofa conformation. A strong O-H,O inter molecular interaction plays a key role in the formation of dimer along b-axis. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

    Better Performance of Monodentate P -Stereogenic Phosphanes Compared to Bidentate Analogues in Pd-Catalyzed Asymmetric Allylic Alkylations

    EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 21 2010
    Arnald Grabulosa
    Abstract The cationic allylpalladium complexes 3a,3f, 4a, 4e, 5e of type [Pd(,3 -2-Me-C3H4)P2]PF6 were synthesized using a group of monodentate P -stereogenic phosphanes, P=PPhRR, (a,f) and diphosphanes (PhRPCH2)2 (1a, 1e) or PhRPCH2Si(Me)2CH2PPhR (2e). The analogous cationic complexes with the disubstituted allyl group (,3 -1,3-Ph2 -C3H3) and monodentate phosphanes were not isolated as stable solids; only [PdCl(,3 -1,3-Ph2 -C3H3)P] (6a, 6d) were obtained. Palladium allyl complexes were screened as precatalysts in the allylic substitution of rac -3-acetoxy-1,3-diphenyl-1-propene (I) and (E)-3-acetoxy-1-phenyl-1-propene (III) with dimethyl malonate as the nucleophile. The various catalytic precursors showed a wide range of activity and selectivity. The bismonodentate phosphane complexes 3 are more active than the bidentate analogues. With regard to the regioselectivity, precursors containing monodentate phosphanes favour the formation of the linear product in the allylic substitution of cinnamyl acetate (III) compared with those containing bidentate phosphanes. With substrate I, compounds with the diphosphanes 1a and 1e, containing a five-membered chelate ring, gave low enantioselectivities (less than 10,% ee), but those with the diphosphane 2e, forming a six-membered chelate ring or with two monodentate phosphanes, afforded products with moderate enantioselectivity under standard conditions (ee up to 74,%). The results show that the performance of precursors containing monodentate phosphanes was superior to those containing bidentate ligands in both activity and selectivity. [source]

    Hydrido-Osmium(II), -Osmium(IV) and-Osmium(VI) Complexes with Functionalized Phosphanes as Ligands,

    EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 35 2009
    Birgit Richter
    Abstract Reaction of five-coordinate [OsHCl(CO)(PiPr3)2] (1) with the chelating phosphane iPr2PCH2CO2Me gave six-coordinate [OsHCl(CO)(PiPr3){,2(P,O)- iPr2PCH2C(=O)OMe}] (2), which upon treatment with CO and O2 afforded the 1:1 adducts [OsHCl(CO)(L)(PiPr3){,(P)- iPr2PCH2CO2Me}] (3, 4) by partial opening of the chelate ring. The vinyl complex [OsCl(CH=CHPh)(CO)(PiPr3){,2(P,O)- iPr2PCH2C(=O)OMe}] (5) was obtained from 2 and PhC,CH by insertion of the alkyne into the Os,H bond. Reaction of 2 with sodium acetate led to metathesis of the anionic ligands and formation of [OsH(,2 -O2CCH3)(CO)(PiPr3){,(P)- iPr2PCH2CO2Me}] (6). Osmium(VI) compounds [OsH6(PiPr2R)2] with R = CH2CH2OMe (12), CH2CO2Me (13) and CH2CO2Et (14), and [OsH6(PiPr3){,(P)- iPr2PCH2CH2NMe2}] (16) were prepared from osmium(IV) precursors and shown to rapidly react with O2 and primary alcohols. Exploratory studies revealed that the catalytic activity of the hexahydrido complexes in the hydrogen transfer reaction from 2-propanol to cyclohexanone and acetophenone depends on the type of the functionalized phosphane and is best for R = CH2CH2OMe. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source]

    Variable Coordination Modes of Benzaldehyde Thiosemicarbazones , Synthesis, Structure, and Electrochemical Properties of Some Ruthenium Complexes

    EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 29 2008
    Swati Dutta
    Abstract Reaction of benzaldehyde thiosemicarbazones [H2LR, where H2 stands for the two protons, the hydrazinic proton, and the phenyl proton at the ortho position, with respect to the imine function and R (R = OCH3, CH3, H, Cl, and NO2) for the para substituent] with [Ru(PPh3)2(CO)2Cl2], carried out in refluxing ethanol, afforded monomeric complexes of type [Ru(PPh3)2(CO)(HLR)(H)]. The crystal structure of the [Ru(PPh3)2(CO)(HLNO2)(H)] complex was determined. The thiosemicarbazone ligand is coordinated to the ruthenium center as a bidentate N,S-donor ligand forming a four-membered chelate ring. When the reaction of the thiosemicarbazones with [Ru(PPh3)2(CO)2Cl2] was carried out in refluxing toluene, a family of dimeric complexes of type [Ru2(PPh3)2(CO)2(LR)2] were obtained. The crystal structure of [Ru2(PPh3)2(CO)2(LCl)2] was determined. Each thiosemicarbazone ligand is coordinated to one ruthenium atom, by dissociation of the two protons, as a dianionic tridentate C,N,S-donor ligand, and at the same time the sulfur atom is also bonded to the second ruthenium center. 1H NMR spectra of the complexes of both types are in excellent agreement with their compositions. All the dimeric and monomeric complexes are diamagnetic (low-spin d6, S = 0) and show intense absorptions in the visible and ultraviolet regions. Cyclic voltammetry of the [Ru(PPh3)2(CO)(HLR)(H)] and [Ru2(PPh3)2(CO)2(LR)2] complexes show the ruthenium(II),ruthenium(III) oxidation within 0.48,0.73 V vs. SCE followed by a ruthenium(III),ruthenium(IV) oxidation within 1.09,1.47 V vs. SCE. Potentials of both the oxidations are found to correlate linearly with the electron-withdrawing character of the substituent R. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source]

    Control of Intramolecular Ether-Oxygen Coordination in the Crystal Structure of Copper(II) Complexes With Dipicolylamine-Based Ligands

    EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 8 2007
    Yuji Mikata
    Abstract Thirteen crystal structures of copper(II) complexes with a series of dipicolylamine (DPA)-derived ligands, N -(2-methoxyethyl)- N,N -bis(2-pyridylmethyl)amine (L1), N -[2-(2-hydroxyethyloxy)ethyl]- N,N -bis(2-pyridylmethyl)amine (L2) and N -(3-methoxypropyl)- N,N -bis(2-pyridylmethyl)amine (L3), have been determined and the factors that control the coordination of the ether-oxygen atom of these ligands to the copper centre are discussed. Complexes that have +1 or +2 charges exhibit coordination of the ether-oxygen atom, whereas neutral complexes in which two anions are bound to the copper(II) centre tend to lose the oxygen coordination. Upon chelation of the oxygen atom, L3 forms a six-membered chelate ring with respect to the 3-aminopropyl ether moiety whereas L1 and L2 form a five-membered chelate. This difference, especially in the nitrate and bromide complexes, determines whether the ether-oxygen atom chelates to the metal centre to give a monocationic complex, or the second anion coordinates to the metal centre to form the ether-free, neutral complex. The terminal anchor hydroxy group of L2 facilitates the ether-oxygen coordination via a hydrogen bond interaction to the donor atom located trans to the aliphatic nitrogen atom in the basal plane. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source]

    Tripyrrinatocadmium Complexes: Enforcing Supramolecular Aggregation by a Large Ion

    EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 7 2007
    Martin Bröring
    Abstract A newly developed method for the preparation of free base tripyrrin ligands HTrpy by cyanide-promoted demetalation of nickel chelates TrpyNiNCO was used in order to explore the chemistry of cadmium tripyrrins TrpyCdX with a variety of anionic co-ligands X. The introduction of the large CdII ion into the tripyrrin N3 coordination site was accomplished by the use of cadmium acetate as the metal precursor. Ligand exchange experiments using sodium salts of different anions disclose a marked tendency for pentacoordination, which is achieved either by the formation of chelates or of 1D coordination polymers that form as a consequence of the size of the central metal. The attempted introduction of chlorido, iodido, or cyanato ligands thus leads mainly to decomposed material, while the use of 1,1,1-trifluoracetylacetonate, salicylate, and acetate ligands results in stable, pentacoordinate and monomeric complexes with the external ligand bound as a four- or six-membered O,O -chelate ring. With the pseudohalogenido ligands thiocyanate, selenocyanate, and azide as well as with the weakly coordinating trifluoroacetate 1D coordination polymers with a variety of chain structures were obtained and investigated by X-ray diffraction studies. Interestingly TrpyCdN3 is present in the crystal as a coordinatively and hydrogen-bonded methanol adduct with a dimeric repeating subunit. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source]

    Oxovanadium(IV) Complexes with Pyrazinecarboxylic Acids:The Coordinating Properties of Ligands with the (Naromatic, COO,) Donor Set

    EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 13 2006
    Eugenio Garribba
    Abstract Complex formation between the VIVO ion and four pyrazine derivatives, 2-pyrazinecarboxylic acid (pzc), 5-methyl-2-pyrazinecarboxylic acid (5-Mepzc), 2,3-pyrazinedicarboxylic acid (3-COOHpzc) and 5-hydroxy-2-pyrazinecarboxylic acid (5-OHpzc), was studied in aqueous solution and in the solid state through the combined application of potentiometric and spectroscopic (EPR and FT-IR) techniques. The results indicate that in acidic and neutral aqueous solution all theligands form mono(chelated), bis(chelated) and dinuclear species of composition VOL, VOL2 and (VO)2L2H,2. Hexacoordinated VOL2 complexes are characterised by a cis/trans isomerism, where cis and trans are the species with a water molecule bound in the cis or trans position with respect to the V=O group. The trans arrangement is favoured over the cis arrangement. Three solid derivatives, [VO(5-Mepzc)2] (1), cis -[VO(pzc)2(H2O)] (2) and cis -[VO(3-COOHpzc)2(H2O)] (3), were isolated and characterised. Based on the experimental results and on the data in the literature, the stability of cis and trans isomers in aqueous solution and in the solid state has been discussed, showing that with ligands of comparable basicity and size of the chelate ring the hydrophilicity favours the cis species and determines the relative amount of the two isomers. The analysis of the magnetic properties of the hydroxo-bridged VIVO dimers suggests that for the (VO)2L2H,2 species the anti -coplanar arrangement is realised. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source]

    Diastereomeric Halfsandwich Rhenium Complexes Containing Hemilabile Phosphane Ligands

    EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 24 2004
    Stefan Dilsky
    Abstract The syntheses and some typical reactions of diastereomeric rhenium complexes [CpRe(NO)(CO){P(Ph)(R)(R,)}]BF4 (R = Me, Ph; R, = 2-C6H4OMe, CH2C4H3S, CH2C4H7O) (3a,e) are described. Reduction of the carbonyl ligand with NaBH4 in THF gave the corresponding methyl complexes [CpRe(NO){P(Ph)(R)(R,)}(CH3)] (4a,e). Acid treatment of the methyl complexes leads to liberation of methane and coordination of the additional donor site of the potentially bidentate phosphane ligand. Of the chelate complexes 5a,e, those with R, = 2-C6H4OMe (5a, d) decomposed in solution at room temperature. In donor solvents, the chelate ring opens giving the stable solvated complexes [CpRe(NO){P(Ph)(R)(R,)}](solvent)]BF4 (solvent = CH3CN, THF) (6b,e, 7d). The new compounds are thus suitable starting materials for the syntheses of diastereomeric rhenium complexes [CpRe(NO){P(Ph)(R)(R,)}(L)]BF4. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source]

    Design, Synthesis, and Spectral Luminescent Properties of a Novel Polycarbocyanine Series Based on the 2,2-Difluoro-1,3,2-dioxaborine Nucleus

    EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 9 2008
    Konstantin Zyabrev
    Abstract The natures of the chromophores in symmetric polymethine dyes derived from 2,2-difluoro-1,3,2-dioxaborine have been investigated. Ab initio quantum chemical calculations demonstrated that the presence of dioxaborine end residues stabilizes the frontier levels of the corresponding polymethine dye and makes electron-density distribution over the oxygen atoms in the chelate ring more even than in the analogous dye structure with boron-free acyclic end groups. A series of novel symmetric polycarbocyanines and a tricarbocyanine series with variously bridged polymethine chromophores have been synthesized from hitherto unknown pyrimidino-annelated dioxaborines. The absorption, fluorescence and 13C NMR spectroscopic data point to the polymethinic type of electron-density distribution in the 2,2-difluoro-1,3,2-dioxaborine polymethine dye molecules. The fundamental options for controlling the spectral properties of these dyes by modification of their polymethine chains have been evaluated. One of the new compounds synthesized is remarkable among the known open-chain polymethine dyes for its record high fluorescence quantum yield. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source]

    Crystal Structure of Garciniaphenone and Evidences on the Relationship between Keto,Enol Tautomerism and Configuration

    HELVETICA CHIMICA ACTA, Issue 7 2008
    Felipe
    Abstract Garciniaphenone (=rel- (1R,5R,7R)-3-benzoyl-4-hydroxy-8,8-dimethyl-1,7-bis(3-methylbut-2-en-1-yl)bicyclo[3.3.1]non-3-ene-2,9-dione; 1), a novel natural product, was isolated from a hexane extract of Garcinia brasiliensis fruits. The crystal structure of 1 as well as the selected geometrical and configurational features were compared with those of known related polyprenylated benzophenones. Garciniaphenone is the first representative of polyprenylated benzophenones without a prenyl substituent at C(5). Notably, the absence of a 5-prenyl substituent has an impact on the molecular geometry. The tautomeric form of 1 in the solid state was readily established by a residual-electronic-density map generated by means of a difference Fourier analysis, and there is an entirely delocalized six-membered chelate ring encompassing the keto,enol moiety. The configuration at C(7) was used to rationalize the nature of the keto,enol tautomeric form within 1. The intermolecular array in the network is maintained by nonclassical intermolecular H-bonds. [source]

    Palladium(II) Complexes of C2 -Bridged Chiral Diphosphines: Application to Enantioselective Carbonyl-Ene Reactions

    ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 8 2010
    He-Kuan Luo
    Abstract (11bR,11,bR)-4,4,-(1,2-Phenylene)bis[4,5-dihydro-3H -dinaphtho[2,1- c:1,,2,- e]phosphepin] [abbreviated as (R)-BINAPHANE], (3R,3,R,4S,4,S,11bS,11,bS)-4,4,-bis(1,1-dimethylethyl)-4,4,,5,5,-tetrahydro-3,3,-bi-3H -dinaphtho[2,1- c:1,,2,- e]phosphepin [(S)-BINAPINE], (1S,1,S,2R,2,R)-1,1,-bis(1,1-dimethylethyl)-2,2,-biphospholane [(S,S,R,R)-TANGPHOS] and (2R,2,R,5R,5,R)-1,1,-(1,2-phenylene)bis[2,5-bis(1-methylethyl)phospholane] [(R,R) -i- Pr-DUPHOS] are C2 -bridged chiral diphosphines that form stable complexes with palladium(II) and platinum(II) containing a five-membered chelate ring. The Pd(II)-BINAPHANE catalyst displayed good to excellent enantioselectivities with ee values as high as 99.0% albeit in low yields for the carbonyl-ene reaction between phenylglyoxal and alkenes. Its Pt(II) counterpart afforded improved yields while retaining satisfactory enantioselectivity. For the carbonyl-ene reaction between ethyl trifluoropyruvate and alkenes, the Pd(II)-BINAPHANE catalyst afforded both good yields and extremely high enantioselectivities with ees as high as 99.6%. A comparative study on the Pd(II) catalysts of the four C2 -bridged chiral diphosphines revealed that Pd(II)-BINAPHANE afforded the best enantioselectivity. The ee values derived from Pd(II)-BINAPHANE are much higher than those derived from the other three Pd(II) catalysts. A comparison of the catalyst structures shows that the Pd(II)-BINAPHANE catalyst is the only one that has two bulky (R)-binaphthyl groups close to the reaction site. Hence it creates a deep chiral space that can efficiently control the reaction behavior in the carbonyl-ene reactions resulting in excellent enantioselectivity. [source]

    A family of thioxanthato ruthenium and osmium aryls

    ISRAEL JOURNAL OF CHEMISTRY, Issue 3 2001
    Swarup Chattopadhyay
    The title complexes of type M(RL2)(PPh3)2(CO)(S2CSEt) (2a: M = Ru; 2b: M = Os) have been synthesized in excellent yields by reacting M(RL1)(PPh3)2(CO)X (1a: M = Ru, × = Cl; 1b: M = Os, × = Br) with potassium ethyl thioxanthate and have been characterized with the help of spectral and electrochemical data. The RL2 ligand in 2 is the imine-phenol tautomer of N-C6H4R(p)-4-methylsalicylaldimine (R = Me, MeO, Cl) coordinated at the carbanionic-C2 atom only while RL1 in 1 is the iminium-phenolato tautomer chelated via carbanionic-C2 and phenolato-O atoms. The synthetic reaction is thus attended with tautomerization of the Schiff base ligand. It is also associated with a rotation of the ligand by ,180° around the M,C bond in order to exclude steric repulsion. These features have been revealed by structure determination of 2a (R = Me). The metallated aldimine ring is found to be highly noncoplanar (dihedral angle ,40°) with the thioxanthate chelate ring due to steric repulsion originating from the relatively large size of the sulfur atom. This phenomenon, which is absent in both the precursor 1 (R = Me) and in the carboxylate analogue Ru(MeL2)(PPh3)2(CO)(O2CMe), 7, has distinctive effects on bond parameters of 2a (R = Me). Thus the two Ru,P bonds in 2a (R = Me) differ in length by as much as 0.06 Å. The thioxanthate 2 is thermodynamically more stable than the precursor 1 as well as the carboxylate 7. Accordingly, both of these are irreversibly transformed to 2a (R = Me) upon treatment with thioxanthate. [source]

    AIM and NBO analysis

    MAGNETIC RESONANCE IN CHEMISTRY, Issue 9 2010

    In the series of diaminoenones, large high-frequency shifts of the 1H NMR of the NH group in the cis -position relative to the carbonyl group suggests strong NH···O intramolecular hydrogen bonding comprising a six-membered chelate ring. The NH···O hydrogen bond causes an increase of the 1J(N,H) coupling constant by 2,4 Hz and high-frequency shift of the 15N signal by 9,10 ppm despite of the lengthening of the relevant NH bond. These experimental trends are substantiated by gauge-independent atomic orbital and density functional theory calculations of the shielding and coupling constants in the 3,3-bis(isopropylamino)-1-(aryl)prop-2-en-1-one (12) for conformations with the Z - and E -orientations of the carbonyl group relative to the NH group. The effects of the NH···O hydrogen-bond on the NMR parameters are analyzed with the atoms-in-molecules (AIM) and natural bond orbital (NBO) methods. The AIM method indicates a weakening of the NH···O hydrogen bond as compared with that of 1,1-di(pyrrol-2-yl)-2-formylethene (13) where NH···O hydrogen bridge establishes a seven-membered chelate ring, and the corresponding 1J(N,H) coupling constant decreases. The NBO method reveals that the LP(O) ,,*NH hyperconjugative interaction is weakened on going from the six-membered chelate ring to the seven-membered one due to a more bent hydrogen bond in the former case. A dominating effect of the NH bond rehybridization, owing to an electrostatic term in the hydrogen bonding, seems to provide an increase of the 1J(N,H) value as a consequence of the NH···O hydrogen bonding in the studied diaminoenones. Copyright © 2010 John Wiley & Sons, Ltd. [source]

    Different intermolecular interactions in azido[2-(diphenylphosphino)benzaldehyde semicarbazonato-,2P,N1,O]nickel(II)

    ACTA CRYSTALLOGRAPHICA SECTION C, Issue 7 2009
    Sladjana B. Novakovi
    The title compound, [Ni(C20H17N3OP)(N3)], is the first complex with a semicarbazide-based ligand having a P atom as one of the donors. The influence of the P atom on the deformation of the coordination geometry of the NiII ion is evident but less expressed than in the cases of complexes with analogous seleno- and thiosemicarbazide ligands. The torsion angles involving the two bonds formed by the P atom within the six-membered chelate ring have the largest values [C,P,Ni,N = 24.3,(2)° and C,C,P,Ni = ,24.2,(4)°], suggesting that the P atom considerably influences the conformation of the ring. Two types of N,H...N hydrogen bond connect the complex units into chains. [source]

    Poly[(acetone)tetraaqua[,6 -ethyl (dichloromethylene)diphosphonato][,5 -ethyl (dichloromethylene)diphosphonato]tribarium(II)]

    ACTA CRYSTALLOGRAPHICA SECTION C, Issue 4 2009
    Jonna Jokiniemi
    The novel title compound, [Ba3(C3H5Cl2O6P2)2(C3H6O)(H2O)4]n, has a polymeric two-dimensional network structure which lies parallel to the (10) plane. The asymmetric unit consists of three independent Ba2+ ions, two of them eight-coordinated and the third nine-coordinated, and two independent ethyl (dichloromethylene)diphosphonate(3,) ligands, one acetone ligand and four aqua ligands. The coordination environments around the BaO8 polyhedra are best described as bicapped trigonal prismatic, while the BaO9 polyhedron is in a distorted tricapped trigonal prismatic geometry. The two diphosphonate ligands adopt different coordination modes. Both ligands chelate three metal cations, but one is coordinated to six metal cations in total and forms two six-membered and one four-membered chelate ring, while the other is coordinated to five metal cations in total and forms one six-membered and two four-membered chelate rings, the fifth unsubstituted O atom remaining uncoordinated. [source]

    Directed anisotropy in bis(acetato-,2O,O,)diaquazinc(II) at 110 and 250,K

    ACTA CRYSTALLOGRAPHICA SECTION C, Issue 2 2009
    Martin Lutz
    The molecule of the title compound, [Zn(C2H3O2)2(H2O)2], is located on a twofold axis in the crystal structure. The displacement parameters and the thermal expansion of the crystal show significant anisotropy. This is explained by the two-dimensional hydrogen-bonded structure, with only very weak interactions perpendicular to it. Besides the overall molecular motion, there are internal vibrations, which cause the Zn,O(carboxylate) bonds to fail the Hirshfeld rigid-bond test. It is shown that this can be interpreted in terms of the steric strain in the four-membered chelate ring due to the bidentate carboxylate coordination. [source]

    Tricarbonyl Rhenium(I) and Technetium(I) Complexes with Hydrazones Derived from 4,5-Diazafluoren-9-one and 1,10-Phenanthroline-5,6-dione

    EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 29 2010
    Paula Barbazán
    Abstract Tricarbonylrhenium(I) and -technetium(I) halide (halide = Cl and Br) complexes of ligands derived from 4,5-diazafluoren-9-one (df) and 1,10-phenanthroline-5,6-dione (phen) derivatives of benzoic and 2-hydroxybenzoic acid hydrazides have been prepared. The complexes have been characterized by elemental analysis, MS, IR, 1H NMR and absorption and emission UV/Vis spectroscopic methods. The metal centres (ReI and TcI) are coordinated through the nitrogen imine atoms and establish five-membered chelate rings, whereas the hydrazone groups stand uncoordinated. The 1H NMR spectra suggest the same behaviour in solution on the basis of only marginal variations in the chemical shifts of the hydrazine protons. [source]

    Structural Trends in Divalent Benzil Bis(thiosemicarbazone) Complexes

    EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 21 2005
    David G. Calatayud
    Abstract Redox-related changes in the biological properties of copper bis(thiosemicarbazones) are induced by the backbone of the ligand. To get information about how these changes depend on the structural parameters, three X-ray structures of complexes with different behaviour of the benzil bis(thiosemicarbazone) ligand have been determined. These include two almost planar copper(II) complexes with different grades of deprotonation in the ligand and a ZnII complex in which the ligand acts as a monoanion and a nitrate group is bonded to the metal ion in a square-based pyramid. The changes in the backbone bond lengths agree with the variation in the ionic radius and with the grade of electronic charge delocalisation in the chelate rings; these have consequences for the coordination sphere, allowing the metal to fit slightly better into the ligand cavity, which in turn may affect the complex stability and the redox potential. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source]

    Sodiated ,-Diphosphonate Carbanions: Characterization of the Tetrameric Cubane and the Hexameric Ladder Complexes [{(iPrO)2P(O)}2CHNa]4 and [{(EtO)2P(O)}2CHNa]6

    EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 18 2003
    Roger Nassar
    Abstract Reaction of the methylene diphosphonates [(RO)2P(O)]2CH2, where R = iPr or Et, with the metalating reagents NaH, nBuNa or the superbasic mixture tBuONa/nBuLi leads to monodeprotonation, and formation of the complexes [{(iPrO)2P(O)}2CHNa]4 (1) and [{(EtO)2P(O)}2CHNa]6 (2). Single-crystal X-ray diffraction studies revealed that 1 is tetrameric in the solid state, with a central Na4O4 cubane core. Each metal in 1 is rendered pentacoordinate by binding to three ,3 -O phosphoryl bridges within the cubane, a chelating phosphoryl unit, and also a single iPrO group. In contrast, the structure of 2 is hexameric, and is composed of an unusual six-rung Na6O6 ladder core. Three distinct sodium environments as well as ,1 -, ,2 - and ,3 -O phosphoryl units are present within the ladder framework. No Na,C interactions are present in either 1 or 2. All of the six-membered NaOPCPO chelate rings display localized P=O double bonds and partial multiple bonding on the P,C,P linkages (mean P,O: 1.49 Å, and mean P,C: 1.69 Å). Ab initio molecular orbital calculations (HF/6,31G*) on model complexes indicate that the hexameric arrangement found for 2 is thermodynamically more stable than the cubane structure of 1, in the absence of steric effects. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source]

    Lagoden dimethylformamide hemisolvate dihydrate: absolute configuration, dipolar interactions and hydrogen-bonding interactions

    ACTA CRYSTALLOGRAPHICA SECTION C, Issue 10 2009
    Barbara Wicher
    Lagoden (L·3H2O, where L is Na+·C20H33O6,; sodium 3,,16,18-trihydroxy-8,13- epi -9,13-epoxylabdan-15-oate trihydrate) is widely used as an effective haemostatic agent. It has been crystallized from dimethylformamide (DMF) as sodium 3,,16,18-trihydroxy-8,13- epi -9,13-epoxylabdan-15-oate dimethylformamide hemisolvate dihydrate, Na+·C20H33O6,·0.5C3H7NO·2H2O or L2·DMF·4H2O, and the asymmetric unit contains two of the latter formulation. The four symmetry-independent Na+ cations and lagoden anions, one DMF molecule and six of the eight symmetry-independent water molecules assemble into a one-dimensional polymeric structure via dipolar and hydrogen-bonding interactions. The lagoden anions coordinate to the Na+ cations via the carboxylate groups and the two primary hydroxy groups, whereas the secondary OH groups are solely involved in hydrogen bonding. Two of the four symmetry-independent lagoden anions act in a chelating mode, forming seven-membered chelate rings. The absolute structure, based on anomalous dispersion data collected at 130,K with Cu K, radiation, confirms an inverted configuration at chiral centres C8 and C13 (labdane numbering) relative to the labdane skeleton. [source]

    {4-[(Carbamimidoylhydrazono)methyl-,2N1,N4]-5-hydroxymethyl-2-methylpyridinium-3-olate-,O}(methanol-,O)copper(II) dinitrate

    ACTA CRYSTALLOGRAPHICA SECTION C, Issue 9 2009
    Vukadin M. Leovac
    The title compound, [Cu(C9H13N5O2)(CH4O)](NO3)2, consists of square-planar cationic complex units where the CuII centre is coordinated by an N,N,,O -tridentate pyridoxal,aminoguanidine Schiff base adduct and a methanol molecule. The tridentate ligand is a zwitterion exhibiting an almost planar conformation. The dihedral angles between the mean planes of the pyridoxal ring and the six- and five-membered chelate rings are all less than 2.0°. The charge on the complex cation is neutralized by two nitrate counter-ions. Extensive N,H...O and C,H...O hydrogen bonding connects these ionic species and leads to the formation of layers. The pyridoxal hydroxy groups are the only fragments that deviate significantly from the flat layer structure; these groups are involved in O,H...O hydrogen bonding, connecting the layers into a three-dimensional crystal structure. [source]

    Poly[(acetone)tetraaqua[,6 -ethyl (dichloromethylene)diphosphonato][,5 -ethyl (dichloromethylene)diphosphonato]tribarium(II)]

    ACTA CRYSTALLOGRAPHICA SECTION C, Issue 4 2009
    Jonna Jokiniemi
    The novel title compound, [Ba3(C3H5Cl2O6P2)2(C3H6O)(H2O)4]n, has a polymeric two-dimensional network structure which lies parallel to the (10) plane. The asymmetric unit consists of three independent Ba2+ ions, two of them eight-coordinated and the third nine-coordinated, and two independent ethyl (dichloromethylene)diphosphonate(3,) ligands, one acetone ligand and four aqua ligands. The coordination environments around the BaO8 polyhedra are best described as bicapped trigonal prismatic, while the BaO9 polyhedron is in a distorted tricapped trigonal prismatic geometry. The two diphosphonate ligands adopt different coordination modes. Both ligands chelate three metal cations, but one is coordinated to six metal cations in total and forms two six-membered and one four-membered chelate ring, while the other is coordinated to five metal cations in total and forms one six-membered and two four-membered chelate rings, the fifth unsubstituted O atom remaining uncoordinated. [source]

    A square-planar NiII complex with an asymmetric coordination of a novel polynucleative 2,6-diacetylpyridine bis{[2-(hydroxyimino)propanoyl]hydrazone} ligand

    ACTA CRYSTALLOGRAPHICA SECTION C, Issue 3 2008
    Maxym V. Plutenko
    The title compound, (2,6-diacetylpyridine bis{[2-(hydroxyimino)propanoyl]hydrazone}(2,))nickel(II) dimethyl sulfoxide solvate monohydrate, [Ni(C15H17N7O4)]·C2H6OS·H2O, represents the first example of square-planar N4 coordination via N atoms with four different functions, namely amide, azomethine, hydroxyimino and pyridine. The coordination polyhedron of the central Ni atom has a slightly distorted square-planar geometry. The 2,6-diacetylpyridine bis{[2-(hydroxyimino)propanoyl]hydrazone} ligand forms one six- and two five-membered chelate rings, and a pseudo-chelate ring through an intramolecular hydrogen bond with an amide group as donor and a deprotonated hydroxyimino group as acceptor, resulting in a pseudomacrocyclic arrangement. [source]

    Synthesis, structural characterization and cytotoxic activity of diorganotin(IV) complexes of N -(5-halosalicylidene)tryptophane

    APPLIED ORGANOMETALLIC CHEMISTRY, Issue 1 2009
    Laijin Tian
    Abstract Four new diorganotin(IV) complexes of N -(5-halosalicylidene)tryptophane, R2Sn[5-X-2-OC6H3CHNCH(CH2Ind)COO] [Ind = 3-indolyl; R, X = Et, Cl (1); Et, Br(2); n -Bu, Cl (3); n -Bu, Br (4)], were synthesized and characterized by elemental analysis, IR and NMR (1H, 13C and 119Sn) spectra. The crystal structures of complexes 1,3 were determined by X-ray single crystal diffraction and showed that the tin atoms are in a distorted trigonal bipyramidal geometry and form five- and six-membered chelate rings with the tridentate ligand. Intermolecular weak interactions in 1,3 link molecules, respectively, into a two-dimensional array, a one-dimensional infinite chain and a one-dimensional double-chain supramolecular structure. Bioassay results of the compounds indicated that the dibutyltin complexes 3 and 4 have potent in vitro cytotoxic activity against two human tumor cell lines, CoLo205 and Bcap37, while the diethyltin complexes 1 and 2 display weak cytotoxic activity. Copyright © 2008 John Wiley & Sons, Ltd. [source]

    Poly­[iron(II)-di-,-imidazole-4,5-di­carboxyl­ato-,3N3,O4:O5]

    ACTA CRYSTALLOGRAPHICA SECTION C, Issue 6 2004
    Ying Xu
    In the title compound, [Fe(C5H3N2O4)2]n, each Fe atom lies on a centre of symmetry, in an octahedral coordination environment consisting of two chelate rings [Fe,N = 2.154,(3),Å and Fe,O = 2.180,(3),Å] and two carboxyl­ate O atoms [Fe,O = 2.111,(2),Å] from imidazole-4,5-di­carboxyl­ate ligands. Extensive hydrogen-bonding interactions exist between layers constructed of Fe4 squares, forming tunnels along the a axis with large voids. [source]

    cis,cis,cis -(Acetato- O,O,)­bis­[1,2-bis­(di­phenyl­phosphino)­ethane- P,P,]­ruthenium(II) hexa­fluoro­phosphate di­methanol solvate

    ACTA CRYSTALLOGRAPHICA SECTION C, Issue 9 2000
    Nigel T. Lucas
    In the cation of the title complex, cis,cis,cis -[Ru(,2 -O2CMe)(dppe)2]PF6·2MeOH [dppe is 1,2-bis­(di­phenyl­phosphino)­ethane, C26H24P2], the Ru atom is in a pseudo-octahedral coordination environment with two chelating dppe ligands and one chelating acetate ligand. Intra-phosphine and intra-acetate bond lengths and angles are unexceptional. Deviations from idealized octahedral coordination angles at ruthenium [O,Ru,O 59.43,(8)° and P,Ru,P 103.19,(2)°] presumably derive from constraints imposed by the chelate rings. The Ru,P distances for the mutually trans P-donor atoms [2.3785,(6),Å] are significantly longer than those for the Ru,P linkages trans to the acetate ligand [2.3074,(6),Å]. The Ru1, C1 and C2 atoms lie on a twofold axis, and atom P3 of the anion lies on an inversion centre. [source]