- Heterobimetallic copper-barium complexes for deposition of composite oxide thin films
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Heterobimetallic molecular precursors [Ba(dmap)4Cu 4(OAc)6·THF] (1) and [Ba(dmap)4Cu 4(TFA)6·THF] (2) [dmap = N,N- dimethylaminopropanolate, OAc = acetate and TFA = trifluoroacetate] for th
- Tahir, Asif Ali,Mazhar, Muhammad,Hamid, Mazhar,Zeller, Matthias,Hunter, Allen D.
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- Spin-singlet Quantum Ground State in Zigzag Spin Ladder Cu(CF3COO)2
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The copper salt of trifluoroacetic acid, Cu(CF3COO)2, offers a new platform to investigate the quantum ground states of low-dimensional magnets. In practice, it realizes the ideal case of a solid hosting essentially isolated magnetic monolayers. These entities are constituted by well-separated two-leg half-integer spin ladders organized in a zigzag fashion. The ladders are comprised of dimeric units of edge-sharing tetragonal pyramids coupled through carbon ions. The spin-gap state in this compound was revealed by static and dynamic magnetic measurements. No indications of long range magnetic ordering down to liquid helium temperature were obtained in specific heat measurements. First principles calculations allow estimation of the main exchange interaction parameters, J⊥=176 K and J∥=12 K, consistent with the weakly interacting dimers model.
- Danilovich, Igor L.,Karpova, Elena V.,Morozov, Igor V.,Ushakov, Alexey V.,Streltsov, Sergey V.,Shakin, Alexander A.,Volkova, Olga S.,Zvereva, Elena A.,Vasiliev, Alexander N.
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- The Oxidation of Carbon Monoxide as an Integrated Part of the Coupled Alkane Oxidation Process: Gas-Phase Oxidation over Supported Metal-Complex Catalysts
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Heterogeneous rhodium–copper chloride catalysts for gas-phase oxidation processes were prepared via the cold impregnation of γ-Al2O3 with aqueous RhCl3 and CuCl2 solutions. Heptafluorobutyric or pentafluorobenzo
- Chepaikin,Bezruchenko,Menchikova,Tkachenko,Kustov,Kulikov
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- High-field EPR and magnetic susceptibility studies on binuclear and tetranuclear copper trifluoroacetate complexes. X-ray structure determination of three tetranuclear quinoline adducts of copper(II) trifluoroacetate
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Magnetic properties and high-field EPR spectra of three previously unknown tetranuclear quinoline adducts of copper(II) trifluoroacetate were studied, and their X-ray structures were determined. Two green complexes containing a μ4-oxo bridge, C
- Ozarowski, Andrew,Szymanska, Iwona B.,Muziol, Tadeusz,Jezierska, Julia
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- Solvation structure of a copper(II) ion in protic ionic liquids comprising n-hexylethylenediamine
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The fine and dynamic structure of the copper(II) ion solvated in a protic ionic liquid (PIL) comprising monoprotonated N-hexylethylenediaminium (HHexen+) and bis(trifluoromethanesulfonyl)amide (Tf2N-) [or trifluoroacetate (TFA-)] was determined using NMR,
- Takemura, Shinobu,Kawakami, Sayaka,Harada, Masafumi,Iida, Masayasu
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- Volatile and Thermally Stable Polymeric Tin Trifluoroacetates
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Tin trifluoroacetates are effective vapor phase single-source precursors for F-doped SnO2, but their structures have been poorly understood for decades. Here we undertook a comprehensive structural analysis of these compounds in both the solid and gas phases through a combined single-crystal X-ray crystallography, gas phase electron diffraction, and density functional theory investigation. Tin(II) bis(trifluoroacetate) (1) thermally decomposes into a 1:1 mixture of 1 and ditin(II) μ-oxybis(μ-Trifluoroacetate) (2) during sublimation, which then polymerize into hexatin(II)-di-μ3-oxyoctakis(μ-Trifluoroacetate) (3) upon solidification. Reversible depolymerization occurred readily upon heating, making 3 a useful vapor phase precursor itself. Tin(IV) tetrakis(trifluoroacetate) (5) was also found to be polymeric in the solid state, but it evaporated as a monomer over 130 °C lower than 3. This counterintuitive improvement in volatility by polymerization was possibly due to the large entropy change during sublimation, which offers a strategic new design feature for vapor phase deposition precursors.
- Masuda, Jason D.,Rankine, Conor D.,Wann, Derek A.,Ba?i?, Goran,Barry, Seán T.
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- Formation of ionic liquids of divalent metal complexes comprising N?alkylethylenediamines and the solvation of the nickel(II) complexes
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A series of divalent N?alkylethylenediamine (alkyl?en) metal(II) (alkyl = hexyl, 2?ethylhexyl, octyl, dodecyl; metal = Ni, Cu, and Zn) complexes was prepared and their phase behavior was studied using differential scanning calorimetry. This kind of metal complexes is very useful for systematically investigating the relationship between phase behavior and molecular structures. It was found that several of the zinc(II) and nickel(II) complexes form room-temperature ionic liquids (RTILs), despite the divalent cation. Although the solid-to-liquid transition temperatures of metal(II) complex-based ILs are typically higher than those of the more common monovalent ionic liquids (ILs), they are dependent on the nature and combination of the metal(II) ions, alkyl chains, and counter anions. The zinc(II) complexes coupled with weakly coordinating bis(fluorosulfonyl)amide (FSA) or bis(trifluoromethanesulfonyl)amide (Tf2N) anions have significantly lower melting points, which is attributable to the longer distance between the zinc(II) ions and the counter anions upon the formation of tetrahedral bis(alkyl?en)zinc(II) complexes as compared to the corresponding distances in NO3 and trifluoroacetate (TFA) complexes. The correlation of melting points with the molecular structures of the zinc(II) complexes is similar to that for the silver(I) alkyl?en complexes. The tris(alkyl?en)nickel(II) complexes coupled with Tf2N counter ions do not readily solidify and have glass transition temperatures below 0 °C, whereas the corresponding bis complexes have much higher melting points despite the counter-ions residing in the outer-spheres of the nickel(II) ions. The interactions of NO3, TFA, FSA, and Tf2N anions with the nickel(II) ions of the bis(alkyl?en) complexes and their solvation behaviors were also studied in organic solvents using visible absorption spectroscopy based on the structures of the neat states. The characteristic solvation behaviors of the nickel(II) complexes were rationalized in terms of the counter anions and solvents.
- Yasuda, Haruka,Nakayama, Chisayo,Iida, Masayasu
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p. 169 - 177
(2018/08/21)
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- One-pot synthesis of 2,4,5-triarylimidazoles catalyzed by copper (II) trifluoroacetate under solvent-free conditions
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A simple, efficient and eco-friendly procedure has been developed using copper(II) trifluoroacetate as catalyst for the synthesis of 2,4,5-triarylimidazoles by one-pot condensation of benzil, aldehydes and ammonium acetate under solvent-free conditions. Compared with traditional methods, the present methodology offers several advantages such as excellent yields, and environmentally benign milder reaction conditions. Moreover, the catalyst exhibits reusable activity.
- Song, Dailei,Liu, Chunsheng,Zhang, Shaohua,Luo, Genxiang
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p. 145 - 147
(2010/10/19)
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- Synthesis and x-ray diffraction analysis of copper(II) fluoroacetates Cu(CF3COO)2 and Cu(CHF2COO)2 · 0.5H2O containing polymeric chains in their structures
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Cu(CF3COO)2 (I) and Cu(CHF2COO)2 · 0.5H2O (II) were synthesized and studied by X-ray diffraction analysis. Crystals I are orthorhombic, a = 16.970(6), b = 10.515(4), c = 9.041(3) A, V = 1613(1)A3, space group Pcca, Z = 8, R1 = 0.0350. Crystals II are monoclinic, a = 12.770(2), b = 13.493(2), c = 8.704(1) A, β = 90.09(2)°, V = 1499.7(4) A3, space group C2/c, Z = 8, R1 = 0.0374. The coordination environment of the Cu atom in I is trigonal-bipyramidal with Cu-O distances of 1.909-2.441 A in the dimeric structural units and 2.058 A between the dimers. In structure II, the copper coordination geometry is tetragonal-pyramidal with Cu-O distances of 1.935-2.315 A.
- Karpova,Boltalin,Korenev,Troyanov
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p. 361 - 366
(2008/10/08)
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- Studies of new volatile copper(I) complexes with triphenylphosphite and perfluorinated carboxylates
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Copper(I) complexes with triphenylphosphite and aliphatic perfluorinated carboxylates of the type [Cu(μ-RCOO){P(OC6H5)3}]2, where R=CF3, C2F5, C3F7, C6F13, C7F15, C8F17 and C9F19 have been prepared as viscous liquids and characterised by 13C, 19F, 31P, 63Cu NMR, IR and mass spectra. In the liquid state, a dimeric structure with Cu in trigonal symmetry linked by the bridging carboxylates is proposed. Temperature-dependent 31P and 63Cu NMR spectra were determined, in the 333-233 K range and single lines from both nuclei were detected, suggesting the fast exchange of triphenylphosphite in acetonitrile solution. Copper relaxation is sufficiently slow to record the signal, which is the first time that this has been reported for complexes with P(OC6H5)3. Examination of 13C and 19F resonances confirm coordination of carboxylates in solution where few dimeric species with a geometry lower than Td symmetry can exist. Thermal decomposition of complexes proceeds as a multistage process, yielding a mixture of Cu, Cu2O and Cu2P2O7. Elsevier Science Ltd.
- Szlyk,Szymanska
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p. 2941 - 2948
(2008/10/09)
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- Synthesis, Structural Characterisation and Studies of Octanuclear Copper Complexes of Pyridonate and Carboxylate Ligands
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A series of octanuclear copper(II) complexes has been prepared which features carboxylate and 2-pyridonate ligands.These compounds have the general formula (where R = Me, Ph or CF3, and L = 6-chloro-, 6-bromo- or 6-methyl-2-pyridonate).X-Ray structural analyses of the acetate complexes indicate that the compounds contain an edge-sharing Cu6O2 bitetrahedral core, surrounded by two units.The Cu...Cu contacts within the core vary from 2.92 to 3.58 Angstroem, depending on the ligand bridging the metal-metal vector.Two routes to these complexes have been investigated, one involving reaction of preformed copper pyridonate complexes with copper carboxylates, the second involving reaction of copper carboxylates with molten HL.Differential scanning calorimetry and thermogravimetric analysis studies of the latter route show it proceeds via formation of copper pyridonate complexes.The FAB mass spectral results show interesting fragmentation patterns, consistent with the observed structures, and NMR spectra of the octanuclear complexes show paramagnetically shifted resonances due to both the pyridonate and carboxylate ligands.Magnetic studies of (L = 6-chloro- or 6-bromo-2-pyridonate) show largely antiferromagnetic exchange coupling within the Cu6O2 core.The structure of the complexes and the magnitude of the couplings lead to spin-frustrated systems, with subtle differences between the two complexes studied.
- Blake, Alexander J.,Grant, Craig M.,Gregory, Christopher I.,Parsons, Simon,Rawson, Jeremy M.,et al.
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p. 163 - 176
(2007/10/02)
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- Reactions of Copper(I) with Micellar Porphyrins and Hemes. Spectroscopic Evidence for Copper(I)-Heme Binuclear Ion Formation
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Addition of cuprous ion to sodium dodecyl sulfate solubilized porphyrins and ferrihemes containing olefinic substituent groups gives rise to spectral perturbations diagnostic of Cu(I) ? complexation.The hemes undergo slow subsequent demetalation in acidic solution, forming porphyrin dications; in the presence of high concentrations of Cu(II) ion the corresponding cupriporphyrins are also formed.For ferriprotoporphyrin IX, the rate of product formation is inversely dependent upon the Cu(II) ion concentration; the data are interpreted in terms of a reaction mechanism, the central feature of which is a dynamic equilibrium between oxidized and reduced hemes, i.e., FeIIIPPIX-CuI + Cu(I) = FeIIPPIX-CuI + Cu(II).This interpretation is supported by the observation that the hemes containing electron-withdrawing substituents in β-pyrrolic positions are extensively reduced to the ferro state by copper(I), but hemes lacking these groups remain primarily ferric when mixed with the cuprous reagent.The reduced Fe(II)-Cu(I) and mixed-valent Fe(III)-Cu(I) binuclear ions are discussed as potential structural models for the oxygen-binding site in cytochrome oxidase.
- Deardorff, Eugene A.,Carr, Paulette A. G.,Hurst, James K.
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p. 6611 - 6616
(2007/10/02)
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