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Bromide Anions (bromide + anion)
Selected AbstractsSynthesis and SFM Study of Comb-Like Poly(4-vinylpyridinium) Salts and Their Complexes with SurfactantsMACROMOLECULAR RAPID COMMUNICATIONS, Issue 13 2006Marat O. Gallyamov Abstract Summary: Poly(4-vinylpyridinium) bromides containing octyl and dodecyl pendant groups were synthesized. Bromide anions in these polymer salts were substituted with dodecylsulfate and bis(2-ethylhexylsuccinate) anions using ion-exchange reactions. Initially, P4VP and its derivatives loaded with hydrophobic groups were deposited on a mica surface from diluted solutions in chloroform for visualization. Images of single adsorbed macromolecules were obtained using scanning force microscopy. Original P4VP chains form partially compacted self-intersecting coils. Loading the polymer chains with large hydrophobic groups and especially the increase in the number of alkyl tails (see Figure) per monomer unit of the polymer chain leads to the stretching of the coils, and the comb-like macromolecules adopt more and more extended self-avoiding 2D conformations when deposited on the substrate. Polymer chains with large hydrophobic groups and increasing number of alkyl tails per monomer unit of the polymer chain. [source] Aluminium Complexes of a Phenoxyimine Ligand with a Pendant Imidazolium Moiety: Synthesis, Characterisation and Evidence for Hydrogen Bonding in SolutionEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 35 2008Stefano Milione Abstract Novel alkylaluminium complexes (phim)AlMe2 (1) and(phimid)AlR2+Br, [R = Me (2), R = iBu (3)] bearing the Schiff base ligands 3,5- tBu2 -2-(OH)C6H2CH=NiPr (phim -H) and3,5- tBu2 -2-(OH)C6H2CH=NCH2CH2[CH(NCHCHNiPr)]Br(phimid -H·Br) have been prepared and fully characterised. Complexes 1,3 each have a tetrahedral structure, with the aluminium atom surrounded by the oxygen and nitrogen atoms of the chelating ligand and two alkyl groups. The structures of phimid -H·Br and of complex 1 have been determined by X-ray diffraction studies. Investigation of the solution structures of 1,3 by 1H NMR spectroscopy revealed that the coordinated phimid ligand is involved in hydrogen bonding with bromide anion. Treatment of 1 with B(C6F5)3 led smoothly to (phim)Al(C6F5)Me (4) by transfer of a C6F5 group from MeB(C6F5)3, to the initially formed coordinatively unsaturated cationic intermediate. In contrast, treatment of 2 with one equiv. of B(C6F5)3 afforded the cationic monomethyl species (phimid)AlMeBr+,MeB(C6F5)3, (5), stabilised by the coordination of the bromide anion acting as a Lewis base.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] Imidazolium based ionic liquid crystals: structure, photophysical and thermal behaviour of [Cnmim]Br·xH2O (n = 12, 14; x=0, 1)CRYSTAL RESEARCH AND TECHNOLOGY, Issue 11 2008A. Getsis Abstract The long chain imidazolium halides [Cnmim]Br·xH2O (n = 10, 12; x = 0, 1) have been synthesized and their structural and thermal behaviour together with their photophysical properties characterized. X-ray structure analyses of the monohydrates ([C12mim]Br·H2O: triclinic, P1, no. 2, Z = 2, Pearson code aP112, a = 550.0(5) pm, b = 779.4(5) pm, c = 2296.1(5) pm, , = 81.89(5)°, , = 83.76(5)°, , = 78.102(5)°, 3523 unique reflections with Io > 2,(Io), R1 = 0.0263, wR2 = 0.0652, GooF = 1.037, T = 263(2) K; [C14mim]Br,H2O: triclinic, P1, no. 2, Z = 12, Pearson code aP11, a = 549.86(8) pm, 782.09(13) pm, c = 2511.3(4) pm, , = 94.86(2)°, , = 94.39(2)°, , = 101.83(2)°, 2063 unique reflections with Io > 2,(Io), R1 = 0.0429, wR2 = 0.0690, GooF = 0.770, T = 293(2) K) show for both compounds similar bilayered structures. Sheets composed of hydrophilic structure regions constituted by positively charged imidazolium head groups, bromide anions and hydrogen bonded water alternate with hydrophobic areas formed by interdigitated long alkyl chains belonging to imidazolium cations with different orientation. Combined differential scanning calorimetry and polarizing optical microscopy shows that the monohydrates as well as the anhydrous imidazolium salts are thermotropic liquid crystals which adopt smectic mesophases. The mesophase region is larger in case of the monohydrates when compared to the anhydrous compounds indicating that water obviously stabilizes the mesophase. All compounds show an intense whitish photoluminescence with short lived (1,,1,*) and long lived (1,,3,*) transitions. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Syntheses and Properties of Fluorous Quaternary Phosphonium Salts that Bear Four Ponytails; New Candidates for Phase Transfer Catalysts and Ionic LiquidsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 12-13 2006Charlotte Emnet Abstract The fluorous tertiary phosphine [Rf6(CH2)2]3P [Rfn=CF3(CF2)n,1] and excess PhCH2Br, CH3(CH2)3OSO2CF3, or Rf6(CH2)2OSO2CF3 react (CF3C6H5, 45,110,°C) to give the phosphonium salts (PhCH2)[Rf6(CH2)2]3P+ Br, (2, 71,%), [CH3(CH2)3][Rf6(CH2)2]3P+ CF3SO3, (3, 65,%), or [Rf6(CH2)2]4P+ CF3SO3, (4, 83,%). The phosphines [Rf6(CH2)2]2[Rf8(CH2)2]P and [Rf8(CH2)2]3P are similarly elaborated with Rf6(CH2)2I, Rf8(CH2)2I, or Rf8(CH2)2Br (DMF, 115,°C) to [Rf8(CH2)2]4- x[Rf6(CH2)2]xP+ I, (x=3, 7; 2, 8; 1, 9; 0, 10) or [Rf8(CH2)2]4P+ Br, (80,60,%). The salts exhibit melting points between 110,°C and 43,°C, with lower values favored by less symmetrical cations, Rf6 segments, and triflate and bromide anions. Solubilities decrease in the solvent sequence CF3C6F5 (all salts at least moderately soluble, room temperature)>acetone>THF>CF3C6H5>CF3C6F11>CH3C6H5, Et2O, CH2Cl2, hexane (all salts insoluble at elevated temperatures); some appreciably increase upon heating. Partition coefficients are very biased towards fluorous phases (>93:<7). The salts can be quite efficient at extracting picrate from water into CF3C6F5 (97,86,% for 2, 4, 9, 10) or CF3C6H5 (85,66,% for 2 - 4), demonstrating their potential for phase transfer catalysis. A CF3C6F5 solution of Rf8(CH2)3I and aqueous NaCl react at 100,°C in the presence (but not the absence) of 9 to give Rf8(CH2)3Cl. [source] Conformational Behaviour of Comb-Like Poly(4-vinylpyridinium) Salts and their Complexes with Surfactants in Solution and on a Flat SurfaceMACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 2 2007Marat O. Gallyamov Abstract We synthesised P4VP bromides with octyl and dodecyl pendant groups; the bromide anions in these polymer salts were further substituted with dodecylsulfate or bis(2-ethylhexylsuccinate) anions. Direct SFM visualisation of the original P4VP chains, of the macromolecular salts and of their complexes, showed that the attachment of the pendant groups and especially the complexation with the surfactants promotes stretching of the macromolecules while adsorbing on mica substrate. On the other hand, viscosimetry showed that in solution (chloroform) the comb-like chains and their complexes with dodecylsulfate had more compact conformations than those of the original P4VP. The scaling exponents describing the correlation between the contour length and the end-to-end distance of the adsorbed macromolecules were found to be ca. 3/4, which is indicative of 2D self-avoiding walk statistics. [source] Superspace description of the modulated structure of the metal-salt-hybrid Bi7,,,,Ni2Br5,,,2, (, = 1/9)ACTA CRYSTALLOGRAPHICA SECTION B, Issue 5 2009B. Wahl The compound Bi7,,,,Ni2Br5,,,2, = (Bi3Ni)2[Bi1,,,,Br4]Br1,,2, (, = 1/9) is a sub-bromide of the intermetallic phase Bi3Ni. Its crystal structure contains metallic rods, [Bi3Ni], which are embedded in a salt-like matrix of bromido-bismuthate(III) and bromide anions. The non-stoichiometry originates from the variation of the number n of trans edge-sharing octahedra in the [BinBr4n,+,2](n,+,2), oligomers (3 ,n, 5), as well as from vacancies on the sites of the isolated Br atoms. The simplified structure is described in the orthorhombic space group Cmcm with a = 4.0660,(4), b = 23.305,(3), c = 17.130,(2),Å. It shows a statistical distribution of vacancies and orientational disorder of the concatenated octahedra. By choosing the modulation vector q = a*/9 + b*/2, the additional weak reflections of the diffraction pattern can be indexed. In the [3,+,1]-dimensional superspace group Pmnm(,½0)000, an ordered structure model is achieved. The modulated crystal structure bears a strong resemblance to the somewhat higher oxidized sub-bromide Bi7,,,,Ni2Br5 (, = 1/9). [source] Two different one-dimensional structural motifs in [catena -{Cu(tacn)}2Pd(CN)4]Br2·[catena -Cu(tacn)Pd(CN)4]2·H2O (tacn is 1,4,7-triazacyclononane)ACTA CRYSTALLOGRAPHICA SECTION C, Issue 7 2009Juraj Kuchár The title compound, catena -poly[[bis[(triazacyclononane-,3N,N,,N,,)copper(II)]-di-,-cyanido-,4N:C -palladate(II)-di-,-cyanido-,4C:N] dibromide bis[[(triazacyclononane-,3N,N,,N,,)copper(II)]-,-cyanido-,2N:C -[dicyanidopalladate(II)]-,-cyanido-,2C:N] monohydrate], {[Cu2Pd(CN)4(C6H15N3)2]Br2·[Cu2Pd2(CN)8(C6H15N3)2]·H2O}n, (I), was isolated from an aqueous solution containing tacn·3HBr (tacn is 1,4,7-triazacyclononane), Cu2+ and tetracyanidopalladate(2,) anions. The crystal structure of (I) is essentially ionic and built up of 2,2-electroneutral chains, viz. [Cu(tacn)(NC),Pd(CN)2,(CN),], positively charged 2,4-ribbons exhibiting the composition {[Cu(tacn)(NC)2,Pd(CN)2,Cu(tacn)]2n+}n, bromide anions and one disordered water molecule of crystallization. The O atom of the water molecule occupies two unique crystallographic positions, one on a centre of symmetry, which is half occupied, and the other in a general position with one-quarter occupancy. One of the tacn ligands also exhibits disorder. The formation of two different types of one-dimensional structural motif within the same structure is a unique feature of this compound. [source] The double-layered hydroxide 3CaO·Al2O3·0.5CaBr2·0.5CaCl2·10H2OACTA CRYSTALLOGRAPHICA SECTION C, Issue 2 2001Jean-Philippe Rapin The title compound, calcium oxide,dialuminium trioxide,calcium dibromide,calcium dichloride hydrate (3/1/0.5/0.5/10), also formulated as Ca2Al(OH)6Br0.478Cl0.522·2H2O (dicalcium aluminium hydroxide hemibromide hemichloride dihydrate), is a double-layered hydroxide which belongs to the solid solution Ca2Al(OH)6BrxCl1,x·2H2O, where x can vary from 0 to 1. Chloride and bromide anions of the negatively charged interlayer [Br0.5Cl0.5·2H2O], share statistically the same crystallographic site. Al3+ and Ca2+ cations are coordinated by six and seven O atoms, respectively. All water molecules are bonded to Ca2+ cations and assume the seventh coordination position. Anions in the interlayer are surrounded by ten H atoms. Br, and Cl, are therefore connected to the main layer by ten hydrogen bonds, six of 2.74,(2),Å and four of 2.52,(5),Å, where the donors are hydroxyl groups and water molecules, respectively. Like the chloride equivalent, the title compound is a 6R polytype with trigonal space group Rc and lattice parameters a = 5.7537,(4),Å and c = 48.108,(4),Å. [source] CH-Directed Anion,, Interactions in the Crystals of Pentafluorobenzyl-Substituted Ammonium and Pyridinium SaltsCHEMISTRY - A EUROPEAN JOURNAL, Issue 17 2010Markus Albrecht Prof. Abstract Simple pentafluorobenzyl-substituted ammonium and pyridinium salts with different anions can be easily obtained by treatment of the parent amine or pyridine with the respective pentafluorobenzyl halide. Hexafluorophosphate is introduced as the anion by salt metathesis. In the case of the ammonium salt 4, water co-crystallisation seems to suppress effective anion,, interactions of bromide with the electron-deficient aromatic system, whereas with salts 5 and 6 such interactions are observed despite the presence of water. However, due to asymmetric hydrogen-bonding interactions with ammonium side chains, the anion of 5 is located close to the rim of the pentafluorophenyl group (,1 interaction). In 6 the CH,anion hydrogen bonding is more symmetric and fixes the anion on top of the ring (,6). A similar structure-controlling effect is observed in case of the 1,4-diazabicyclo[2.2.2]octane derivatives 7. Here the position of the anion (Cl, Br, I) is shifted according to the length of the weak CH,halide interaction. The hexafluorophosphate 7,d reveals that this "non-coordinating" anion can be located on top of an aromatic , system. In the methyl-substituted pyridinium salts 9 and 10 different locations of the bromide anions with respect to the , system are observed. This is due to different conformations of the mono- versus disubstituted pyridine, which leads to different directions of the weak, but structurally important, HMeBr bonds. [source] | |||||||||||||