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Chloride Anions (chloride + anion)
Selected AbstractsPhotochemistry of HCl(H2O)4: Cluster Model of the Photodetachment of the Chloride Anion in WaterCHEMINFORM, Issue 19 2003Andrzej L. Sobolewski Abstract For Abstract see ChemInform Abstract in Full Text. [source] N - and C -acyclic thionuleoside analogues of 1,2,3-triazoleHETEROATOM CHEMISTRY, Issue 5 2004Najim A. Al-Masoudi Cycloaddition of the azide derivative 5 with 1,4-dihydroxybutyne afforded the N -thio-acyclic nucleoside 6, which prepared alternatively from coupling of the bromo derivative 8 with 2-acetoxy-ethylmercaptan. Deblocking of 6 gave the free nucleoside 7. Mesylation of 6 furnished the dimesylate 9, which gave three rearranged products 14,16 on treatment with chloride anion. These compounds might be obtained via the episulfonium ion 10, which is subjected to nucleophilic displacement and further sulfur participation. Deblocking of 14,16 afforded the free nucleoside analogues 17,19, and their structures were confirmed by COSY, ROESY, HMQC, and HMBC NMR techniques. Compound 16 was prepared alternatively from chlorination of alcohol 6 with Ph3P-CCl4. Carbomoylation of 6 led to the carbamate 20, which gave the free nucleoside analogue 21 on deblocking. © 2004 Wiley Periodicals, Inc. Heteroatom Chem 15:380,387, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20030 [source] Mechanism of the Nucleophilic Substitution of Acyl Electrophiles using Lithium OrganocupratesADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 7-8 2008Naohiko Yoshikai Abstract The mechanism of nucleophilic substitution reaction at an sp2 carbon center of a thioester or an acid chloride with a lithium organocuprate reagent has been investigated. Density functional calculations indicated that the thioester undergoes oxidative addition of the CS bond to the copper(I) atom through a three-centered transition state to afford an organocopper(III) intermediate, which gives the product through reductive elimination of the alkyl and the acyl groups. On the other hand, the acid chloride loses a chloride anion very easily when it interacts with the cuprate, because the chloride anion is captured by a lithium(I) cation rather than a copper(I) atom. 13C kinetic isotope effect (KIE) experiments showed excellent agreement with computational predictions for the thioester reaction, but suggested that the nucleophilic displacement transition state of the acid chloride occurs much more advanced than the calculations predict. [source] Structural comparison of three N -(4-halogenophenyl)- N,-[1-(2-pyridyl)ethylidene]hydrazine hydrochloridesACTA CRYSTALLOGRAPHICA SECTION C, Issue 7 2010Julia Heilmann-Brohl 2-{1-[(4-Chloroanilino)methylidene]ethyl}pyridinium chloride methanol solvate, C13H13ClN3+·Cl,·CH3OH, (I), crystallizes as discrete cations and anions, with one molecule of methanol as solvent in the asymmetric unit. The N,C,C,N torsion angle in the cation indicates a cis conformation. The cations are located parallel to the (02) plane and are connected through hydrogen bonds by a methanol solvent molecule and a chloride anion, forming zigzag chains in the direction of the b axis. The crystal structure of 2-{1-[(4-fluoroanilino)methylidene]ethyl}pyridinium chloride, C13H13FN3+·Cl,, (II), contains just one anion and one cation in the asymmetric unit but no solvent. In contrast with (I), the N,C,C,N torsion angle in the cation corresponds with a trans conformation. The cations are located parallel to the (100) plane and are connected by hydrogen bonds to the chloride anions, forming zigzag chains in the direction of the b axis. In addition, the crystal packing is stabilized by weak ,,, interactions between the pyridinium and benzene rings. The crystal of (II) is a nonmerohedral monoclinic twin which emulates an orthorhombic diffraction pattern. Twinning occurs via a twofold rotation about the c axis and the fractional contribution of the minor twin component refined to 0.324,(3). 2-{1-[(4-Fluoroanilino)methylidene]ethyl}pyridinium chloride methanol disolvate, C13H13FN3+·Cl,·2CH3OH, (III), is a pseudopolymorph of (II). It crystallizes with two anions, two cations and four molecules of methanol in the asymmetric unit. Two symmetry-equivalent cations are connected by hydrogen bonds to a chloride anion and a methanol solvent molecule, forming a centrosymmetric dimer. A further methanol molecule is hydrogen bonded to each chloride anion. These aggregates are connected by C,H...O contacts to form infinite chains. It is remarkable that the geometric structures of two compounds having two different formula units in their asymmetric units are essentially the same. [source] Hexane-1,6-diaminium chloride [hydrogen bis(chloroacetate)]ACTA CRYSTALLOGRAPHICA SECTION C, Issue 11 2009Agnieszka Paul In the structure of the title compound, C6H18N22+·H(C2H2ClO2)2,·Cl,, the hexane-1,6-diaminium dication is disordered over two sets of positions, with almost equal occupancies. Both alternative positions of the dication are in the fully extended conformation, situated on an inversion centre at (, , ). Two chloroacetic acid moieties, related by another centre of symmetry at (, , ), are connected by a very short symmetrical O...H...O hydrogen bond [O...O = 2.452,(2),Å], with the H atom at the centre of inversion. These two fragments thus effectively form the hydrogen bis(chloroacetate) monoanion, and the overall charge is balanced by an additional chloride anion which resides on a twofold axis. The ions form a layer structure, with alternating layers of dications and anions running along the [101] direction, linked via hydrogen bonds. There are two N,H...O interactions and two N,H...Cl, interactions. [source] Lamotrigine, an antiepileptic drug, and its chloride and nitrate saltsACTA CRYSTALLOGRAPHICA SECTION C, Issue 9 2009Balasubramanian Sridhar In lamotrigine [systematic name: 6-(2,3-dichlorophenyl)-1,2,4-triazine-3,5-diamine], C9H7Cl2N5, (I), the asymmetric unit contains one lamotrigine base molecule. In lamotriginium chloride [systematic name: 3,5-diamino-6-(2,3-dichlorophenyl)-1,2,4-triazin-2-ium chloride], C9H8Cl2N5+·Cl,, (II), the asymmetric unit contains one lamotriginium cation and one chloride anion, while in lamotriginium nitrate, C9H8Cl2N5+·NO3,, (III), the asymmetric unit contains two crystallographically independent lamotriginium cations and two nitrate anions. In all three structures, N,H...N hydrogen bonds form an R22(8) dimer. In (I) and (II), hydrophilic layers are sandwiched between hydrophobic layers in the crystal packing. In all three structures, hydrogen bonds lead to the formation of a supramolecular hydrogen-bonded network. The significance of this study lies in its illustration of the differences between the supramolecular aggregation in the lamotrigine base and in its chloride and nitrate salts. [source] Two oxo complexes with tetranuclear [Fe4(,3 -O)2]8+ and trinuclear [Fe3(,3 -O)]7+ unitsACTA CRYSTALLOGRAPHICA SECTION C, Issue 7 2006Ana María Atria Two new oxo complexes, namely hexa-,2 -acetato-acetatoaquabis(di-3-pyridylamine)di-,3 -oxo-tetrairon(III) chloride monohydrate ethanol 1.25-solvate, [Fe4(C2H3O2)7O2(C10H9N3)2(H2O)]Cl·1.25C2H6O·H2O, (I), containing a tetranuclear [Fe4(,3 -O)2]8+ unit, and 2-methylimidazolium hexa-,2 -acetato-acetatodiaqua-,3 -oxo-triiron(III) chloride dihydrate, (C4H7N2)[Fe3(C2H3O2)7O(H2O)2]Cl·2H2O, (II), with a trinuclear [Fe3(,3 -O)]7+ unit, are presented. Both structures are formed by two well differentiated entities, viz. a compact isolated cluster composed of FeIII ions coordinated to O2, and CH3CO2, anions, and an external group formed by a central Cl, ion surrounded by different solvent groups to which the anion is bound through hydrogen bonding. In the case of (I), charge balance cannot be achieved within the groups, so the structure is macroscopically ionic; in the case of (II), in contrast, each group is locally neutral owing to the internal compensation of charges. The trinuclear complex crystallizes with the metal cluster, chloride anion and 2-methylimidazolium cation bisected by a crystallographic mirror plane. [source] Cloning, expression, purification, crystallization and preliminary X-ray diffraction analysis of chlorite dismutase: a detoxifying enzyme producing molecular oxygenACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 8 2008Daniël C. De Geus Chlorite dismutase, a homotetrameric haem-based protein, is one of the key enzymes of (per)chlorate-reducing bacteria. It is highly active (>2,kU,mg,1) in reducing the toxic compound chlorite to the innocuous chloride anion and molecular oxygen. Chlorite itself is produced as the intermediate product of (per)chlorate reduction. The chlorite dismutase gene in Azospira oryzae strain GR-1 employing degenerate primers has been identified and the active enzyme was subsequently overexpressed in Escherichia coli. Chlorite dismutase was purified, proven to be active and crystallized using sitting drops with PEG 2000 MME, KSCN and ammonium sulfate as precipitants. The crystals belonged to space group P21212 and were most likely to contain six subunits in the asymmetric unit. The refined unit-cell parameters were a = 164.46, b = 169.34, c = 60.79,Å. The crystals diffracted X-rays to 2.1,Å resolution on a synchrotron-radiation source and a three-wavelength MAD data set has been collected. Determination of the chlorite dismutase structure will provide insights into the active site of the enzyme, for which no structures are currently available. [source] A Dual-Response [2]Rotaxane Based on a 1,2,3-Triazole Ring as a Novel Recognition StationCHEMISTRY - A EUROPEAN JOURNAL, Issue 47 2009Haiyan Zheng Abstract Two novel multilevel switchable [2]rotaxanes containing an ammonium and a triazole station have been constructed by a CuI -catalyzed azide,alkyne cycloaddition reaction. The macrocycle of [2]rotaxane containing a C6-chain bridge between the two hydrogen bonding stations exhibits high selectivity for the ammonium cation in the protonated form. Interestingly, the macrocycle is able to interact with the two recognition stations when the bridge between them is shortened. Upon deprotonation of both [2]rotaxanes, the macrocycle moves towards the triazole recognition site due to the hydrogen-bond interaction between the triazole nitrogen atoms and the amide groups in the macrocycle. Upon addition of chloride anion, the conformation of [2]rotaxane is changed because of the cooperative recognition of the chloride anion by a favorable hydrogen-bond donor from both the macrocycle isophthalamide and thread triazole CH proton. [source] Bisamides Derived from Azulene-1,3- and -5,7-dicarboxylic Acids as New Building Blocks for Anion ReceptorsCHEMISTRY - A EUROPEAN JOURNAL, Issue 3 2008Tomasz Zieli, ski Dr. Abstract Bisamides based on the azulene moiety were investigated as building blocks for anion receptors. In the course of these studies, derivatives of azulene-1,3- and -5,7-dicarboxylic acid were synthesized and thoroughly characterized. The anion affinities of the derivatives based on functionalization in the five-membered ring and in the seven-membered ring were determined by 1H,NMR titration. The structural analysis of these building blocks was performed by X-ray diffractometry, molecular modelling and 2D NMR spectroscopy. The five-membered ring derivatives are easy to obtain, offer a binding site preorganized in the syn,syn conformation and bind anions with a strength similar to those of pyrrole-based analogues. There is also strong evidence for aromatic CH,,,anion interactions. The ligands substituted at the 5- and 7-positions offer a binding cleft with an uncommon geometry that originates from the seven-membered ring and seems to be complementary to the chloride anion. [source] Dipyrrolyl-Functionalized Bipyridine-Based Anion Receptors for Emission-Based Selective Detection of Dihydrogen PhosphateCHEMISTRY - A EUROPEAN JOURNAL, Issue 5 2007Patrick Plitt Dr. Abstract New cationic anion receptors, based on the use of pyrrole-substituted bipyridine and coordinated to transition metals, are described. Specifically, polypyridine,ruthenium and ,rhodium cores have been functionalized to generate an anion binding site. The design was chosen to probe the influence of the pyrrole-to-pyrrole separation on anion-binding affinities and selectivities; this distance is greater in the new systems of this report (receptors 1 and 2) relative to that present in related dipyrrolyl quinoxaline based receptors 3 and 4. Solution-phase anion-binding studies, carried out by means of 1H,NMR spectroscopic titrations in [D6]DMSO and isothermal titration calorimetry (ITC) in DMSO, reveal that 1 and 2 bind most simple anions with substantially higher affinity than either 3 or 4. In the case of chloride anion, structural studies, carried out by means of single-crystal X-ray diffraction analyses, are consistent with the solution-phase results and reveal that receptors 1 and 2 are both able to stabilize complexes with this halide anion in the solid state. [source] Anion Recognition by Neutral Macrocyclic AmidesCHEMISTRY - A EUROPEAN JOURNAL, Issue 20 2005J. Chmielewski Dr., Micha Abstract Although amides often serve as anchoring groups in natural and synthetic anion receptors, the structure,affinity relationship studies of amide-based macrocyclic receptors are still very limited. Therefore, we decided to investigate the influence of the size of the macroring on the strength and selectivity of anion binding by uncharged, amide-based receptors. With this aim, we synthesized a series of macrocyclic tetraamides derived from 2,6-pyridinedicarboxylic acid and aliphatic ,,,-diamines of different lengths. X-ray analysis shows that all ligands studied adopt expanded conformations in the solid state with the convergent arrangement of all four hydrogen-bond donors. 1H NMR titrations in DMSO solution revealed a significant effect of the ring size on the stability constants of anion complexes; the 20-membered macrocyclic tetraamide 2 is a better anion receptor than its both 18- and 24-membered analogues. This effect cannot be interpreted exclusively in terms of matching between anion diameter and the size of macrocyclic cavity, because 2 forms the most stable complexes with all anions studied, irrespective of their sizes. However, geometric complementarity manifests in extraordinarily high affinity of 2 towards the chloride anion. The results obtained for solutions were interpreted in the light of solid-state structural studies. Taken together, these data suggest that anion binding by this family of macrocycles is governed by competitive interplay between their ability to adjust to a guest, requiring longer aliphatic spacers, and preorganization, calling for shorter spacers. The 20-membered receptor 2 is a good compromise between these factors and, therefore, it was selected as a promising leading structure for further development of anion receptors. Furthermore, the study of an open chain analogue of 2 revealed a substantial macrocyclic effect. X-ray structure of the acyclic model 14 suggests that this may be due to its ill-preorganized conformation, stabilized by two intramolecular hydrogen bonds. [source] A Ferromagnetically Coupled, Bent, Trinuclear Copper(II) Complex: Synthesis, Structure, Hydrogen-Bonding Network, Magnetic Properties and DNA Interaction StudyEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 17 2006Sumana Sarkar Abstract A bent trinuclear copper(II) complex (1) incorporating ,-phenoxo, ,- syn - syn carboxylato, and ,3 -chloro bridges and an O,N,N -coordinated reduced Schiff-base ligand is reported. The complex shows an intramolecular ferromagnetic interaction in the solid state. The EPR spectra also support the magnetic behaviour of the complex. In the compound, each copper centre has a square-pyramidal geometry. The separation between the adjacent copper ions is about 3.05 Å and that between the terminal copper ions is about 5.0 Å. The complex forms a supramolecular architecture through N,H···Cl hydrogen bonding between the amine group of the reduced Schiff-base ligand and the counter chloride anions. Absorption and fluorescence spectral studies and viscosity measurements have been performed to determine the type of interaction with calf-thymus DNA. The nuclease activity of the complex with plasmid DNA is also studied. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source] Removal of anionic pollutants from groundwaters using Alamine 336: chemical equilibrium modellingJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 11 2006Eugenio Bringas Abstract This work reports the study of the chemical equilibrium of the extraction of chromium(VI) anions from groundwaters where other anionic species are present, mainly sulfate and chloride anions, using Alamine 336 as extractant. The analysis was performed working with two different systems: (i) a binary system (sulfate and chloride anions) and, (ii) a tertiary system (chromium, sulfate and chloride anions) with a composition of 9.6,15.4 mol Cr6+ m,3, 5.2,16.7 mol SO42, m,3 and 4.2,13.5 mol Cl, m,3 respectively. A careful experimental design was performed and the data were correlated to the mathematical models obtaining the equilibrium parameters of the extraction reactions in both systems. Copyright © 2006 Society of Chemical Industry [source] Inhibition of corrosion of AZ91 magnesium alloy in ethylene glycol solution in presence of chloride anionsMATERIALS AND CORROSION/WERKSTOFFE UND KORROSION, Issue 2 2005E. Slavcheva Abstract The influence of chloride ions on the corrosion of AZ91 magnesium alloy in water/ethylene glycol solutions and the inhibiting effect of lactobiono-tallowamide (LTA) were investigated using electrochemical and surface analysis methods. Potentiodynamic polarization curves in aqueous solution of ethylene glycol (50:50w%) containing 0.1 g.L,1 chloride and up to 0.5 g.L,1 LBT were obtained at room and at elevated temperatures. The chloride anions showed a distinct deteriorating effect as they caused pit initiation and accelerated the dissolution of the tested alloy. The selected organic compound demonstrated good protective properties against corrosion of AZ91 magnesium alloy and behaved as inhibitor of mixed type hindering both the cathodic and the anodic partial reactions. It showed inhibition efficiency of 77% at relatively low concentration of 0.2 g.L,1 and was considered as a promising corrosion inhibitor. The mechanism of inhibition was discussed on the basis of the electrochemical impedance spectroscopy (EIS) and XRD analysis of the surface. [source] Structural comparison of three N -(4-halogenophenyl)- N,-[1-(2-pyridyl)ethylidene]hydrazine hydrochloridesACTA CRYSTALLOGRAPHICA SECTION C, Issue 7 2010Julia Heilmann-Brohl 2-{1-[(4-Chloroanilino)methylidene]ethyl}pyridinium chloride methanol solvate, C13H13ClN3+·Cl,·CH3OH, (I), crystallizes as discrete cations and anions, with one molecule of methanol as solvent in the asymmetric unit. The N,C,C,N torsion angle in the cation indicates a cis conformation. The cations are located parallel to the (02) plane and are connected through hydrogen bonds by a methanol solvent molecule and a chloride anion, forming zigzag chains in the direction of the b axis. The crystal structure of 2-{1-[(4-fluoroanilino)methylidene]ethyl}pyridinium chloride, C13H13FN3+·Cl,, (II), contains just one anion and one cation in the asymmetric unit but no solvent. In contrast with (I), the N,C,C,N torsion angle in the cation corresponds with a trans conformation. The cations are located parallel to the (100) plane and are connected by hydrogen bonds to the chloride anions, forming zigzag chains in the direction of the b axis. In addition, the crystal packing is stabilized by weak ,,, interactions between the pyridinium and benzene rings. The crystal of (II) is a nonmerohedral monoclinic twin which emulates an orthorhombic diffraction pattern. Twinning occurs via a twofold rotation about the c axis and the fractional contribution of the minor twin component refined to 0.324,(3). 2-{1-[(4-Fluoroanilino)methylidene]ethyl}pyridinium chloride methanol disolvate, C13H13FN3+·Cl,·2CH3OH, (III), is a pseudopolymorph of (II). It crystallizes with two anions, two cations and four molecules of methanol in the asymmetric unit. Two symmetry-equivalent cations are connected by hydrogen bonds to a chloride anion and a methanol solvent molecule, forming a centrosymmetric dimer. A further methanol molecule is hydrogen bonded to each chloride anion. These aggregates are connected by C,H...O contacts to form infinite chains. It is remarkable that the geometric structures of two compounds having two different formula units in their asymmetric units are essentially the same. [source] A novel 18-membered metallocycle in {2,5-bis[3-(1H -1,3-imidazol-1-ylmethyl)phenyl]-1,3,4-oxadiazole}dichloridocobalt(II)ACTA CRYSTALLOGRAPHICA SECTION C, Issue 6 2010Yan Wu The title molecular complex, [CoCl2(C22H18N6O)], features a novel 18-membered Co-containing metallocycle. The CoII atom lies in a fairly regular tetrahedral geometry defined by two imidazole N-atom donors from one 2,5-bis[3-(1H -1,3-imidazol-1-ylmethyl)phenyl]-1,3,4-oxadiazole (L) ligand and two chloride anions. The coordinating orientation of the L ligand plays an important role in constructing the metallocycle complex. The complexes form a three-dimensional supramolecular assembly via nonclassical C,H...Cl and C,H...N hydrogen bonds and ,,, interactions. [source] Ba5Cl4(H2O)8(VPO5)8: a novel three-dimensional framework solidACTA CRYSTALLOGRAPHICA SECTION C, Issue 3 2010Ai-Yun Zhang The novel hydrothermally synthesized title compound, pentabarium tetrachloride octahydrate octakis(oxovanadium phosphate), Ba5Cl4(H2O)8(VPO5)8, crystallizes in the orthorhombic space group Cmca with a unit cell containing four formula units. Two Ba2+ cations, two Cl, anions and the O atoms of four water molecules are situated on the (100) mirror plane, while the third independent Ba2+ cation is on the intersection of the (100) plane and the twofold axis parallel to a. Two phosphate P atoms are on twofold axes, while the remaining independent P atom and both V atoms are in general positions. The structure is characterized by two kinds of layers, namely anionic oxovanadium phosphate (VPO5), composed of corner-sharing VO5 square pyramids and PO4 tetrahedra, and cationic barium chloride hydrate clusters, Ba5Cl4(H2O)8, composed of three Ba2+ cations linked by bridging chloride anions. The layers are connected by Ba,O bonds to generate a three-dimensional structure. [source] 7-Methoxy-2,3-dioxo-1,4-dihydroquinoxalin-6-aminium chloride monohydrateACTA CRYSTALLOGRAPHICA SECTION C, Issue 1 2010Jürgen Brüning Single crystals of the title compound, C9H10N3O3+·Cl,·H2O, were obtained by recrystallization from hydrochloric acid. The cations stack along the crystallographic a direction. The 2,3-dioxo-1,4-dihydroquinoxaline group shows a significant deviation from planarity [r.m.s. deviation from the best plane = 0.063,(2),Å]. Hydrogen bonding links the cations, chloride anions and water molecules to form an extended three-dimensional architecture. [source] The neutral cluster amminehexa-,2 -chlorido-,4 -oxido-tris(1,4,6-triazabicyclo[3.3.0]oct-4-ene)tetracopper(II)ACTA CRYSTALLOGRAPHICA SECTION C, Issue 6 2009Gina M. Chiarella The title compound, [Cu4Cl6O(C5H9N3)3(NH3)], is a neutral conformationally chiral cluster which crystallizes under the conditions described in this paper as a racemic conglomerate. It contains four CuII atoms in a tetrahedral coordination with a central O atom lying on a crystallographic threefold axis. Six chloride anions bridge the four CuII atoms. Three CuII atoms are bound by an N atom of a monodentate 1,4,6-triazabicyclo[3.3.0]oct-4-ene (Htbo) ligand and the remaining CuII atom is bound by a terminal ammine ligand. The geometry at each copper center is trigonal bipyramidal, produced by the bound N atom of Htbo or ammonia, the O atom in the axial position, and three chloride ions in the equatorial plane. The chloride anions form an octahedron about the oxygen center. The copper,ammonia bond lies along the crystallographic threefold axis, along which the molecules are packed in a polar head-to-tail fashion. [source] The crucial role of C,H...O and C=O..., interactions in the building of three-dimensional structures of dicarboxylic acid,biimidazole compoundsACTA CRYSTALLOGRAPHICA SECTION C, Issue 4 2009Xiao-Li Gao The supramolecular architectures of three dicarboxylic acid,biimidazole compounds, namely, 2,2,-biimidazolium malonate, C6H8N42+·C3H2O42,, (I), 2,2,-bi(1H -imidazole) succinic acid, C6H6N4·C4H6O4, (II), and 2,2,-biimidazolium 2,2,-iminiodiacetate chloride, C6H8N42+·C4H6NO4,·Cl,, (III), are reported. The crystal structures are assembled by the same process, namely double conventional N,H...O or O,H...N hydrogen bonds link the dicarboxylates and biimidazoles to form tapes, which are stacked in parallel through lone-pair,aromatic interactions between carbonyl O atoms and biimidazole groups and are further linked via weak C,H...O interactions. The C=O..., interactions involved in stacking the tapes in (II) and the C,H...O interactions involved in linking the tapes in (II) and (III) demonstrate the crucial role of these interactions in the crystal packing. There is crystallographically imposed symmetry in all three structures. In (I), two independent malonate anions have their central C atoms on twofold axes and two biimidazolium dications each lie about independent inversion centres; in (II), the components lie about inversion centres, while in (III), the unique cation lies about an inversion centre and the iminiodiacetate and chloride anions lie across and on a mirror plane, respectively. [source] Hydrogen-bonded supramolecular motifs in the 1:1 monohydrated molecular adduct of acetoguanaminium chloride with acetoguanamine and in 2,4,6-triaminopyrimidinediium dichloride dihydrateACTA CRYSTALLOGRAPHICA SECTION C, Issue 11 2007Gustavo Portalone In the 1:1 monohydrated molecular adduct 2,4-diamino-6-methyl-1,3,5-triazin-1-ium chloride 2,4-diamino-6-methyl-1,3,5-triazine monohydrate, C4H8N5+·Cl,·C4H7N5·H2O, formed between 2,4-diamino-6-methyl-1,3,5-triazin-1-ium chloride (acetoguanaminium chloride) and 2,4-diamino-6-methyl-1,3,5-triazine (acetoguanamine), and in triaminopyrimidinediium dichloride dihydrate, C4H9N52+·2Cl,·2H2O, whose cationic component lies across a twofold rotation axis, the protonation occurs at the ring N atoms and the bond distances in the protonated molecules indicate significant bond alterations, consistent with charge-separated polar forms. The supramolecular structures of both compounds are stabilized by systems of hydrogen bonds forming complex sheets, interlinked by sets of hydrogen bonds involving the solvent water molecules and the chloride anions. [source] Calcium chloride rhenate(VII) dihydrateACTA CRYSTALLOGRAPHICA SECTION C, Issue 9 2007Urszula Jarek The crystal structure of calcium chloride rhenate(VII) dihydrate, CaCl(ReO4)·2H2O, investigated at 85,K, consists of calcium cations, chloride anions, rhenate(VII) anions and water molecules. In the nearly tetrahedral rhenate(VII) anion, all constituent atoms lie on special positions of m2m (Re) and m (O) site symmetries. The Cl, anion and water O atom lie on special positions of m2m and 2 site symmetries, respectively. The Ca2+ ion, also on a special position (m2m), is eight-coordinated in a distorted square-antiprismatic coordination mode. The crystal has a layered structure stabilized by Ca,O coordination bonds and O,H...Cl hydrogen bonds. [source] Crystallographic report: The [bis(,5 -cyclopentadienyl)titanium(IV)-bis(L -methionine)] dichlorideAPPLIED ORGANOMETALLIC CHEMISTRY, Issue 6 2004Radim Bína Abstract The structure of ionic complex [Cp2Ti(L -Met)2]2+[Cl,]2 (where Cp = ,5 -C5H5) possessing C2 symmetry is presented. Discrete cationic units with distorted tetrahedral geometry around the central titanium atom are connected through intermolecular H···Cl bonds between ammonium group protons of ,-amino acid ligands and chloride anions. Copyright © 2004 John Wiley & Sons, Ltd. [source] Influence of dT20 and [d(AT)10]2 on Cisplatin Hydrolysis Studied by Two-Dimensional [1H,15N] HMQC NMR SpectroscopyCHEMISTRY - A EUROPEAN JOURNAL, Issue 13 2005Jo Vinje Dr. Abstract The influence of the presence of DNA on the kinetics of cisplatin (cis -[PtCl2(NH3)2]) aquation (replacement of Cl, by H2O) and anation (replacement of H2O by Cl,) involved in the hydrolysis of cisplatin have been determined by two-dimensional [1H,15N] HMQC NMR spectroscopy. Single-stranded dT20 and double-stranded [d(AT)10]2 oligonucleotides were used as DNA models, avoiding guanines which are known to react rapidly with aquated cisplatin forms. Reactions starting from cis -[PtCl2(15NH3)2], or from a stoichiometric mixture of cis -[Pt(15NH3)2(H2O)2]2+ and Cl, (all 0.5,mM PtII; in ionic strength, adjusted to 0.095,M or 0.011,M with NaClO4, pH between 3.0 and 4.0) were followed in an NMR tube in both the absence and presence of 0.7,mM dT20 or [d(AT)10]2. In the presence of dT20, we observed a slight and ionic-strength-independent decrease (15,20,%) of the first aquation rate constant, and a more significant decrease of the second anation rate constant. The latter was more important at low ionic strength, and can be explained by efficient condensation of cis -[Pt(15NH3)2(H2O)2]2+ on the surface of single-stranded DNA, in a region depleted of chloride anions. At low ionic strength, we observed an additional set of [1H,15N] HMQC spectral signals indicative of an asymmetric species of PtN2O2 coordination, and we assigned them to phosphate-bound monoadducts of cis -[Pt(15NH3)2(H2O)2]2+. Double-stranded [d(AT)10]2 slowed down the first aquation step also by approximately 15,%; however, we could not determine the influence on the second hydrolysis step because of a significant background reaction with cis -[Pt(NH3)2(H2O)2]2+. [source] | ||||||||||||||||||||||