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1.
Chemical Bonding and Pressure‐Induced Change of the Electron Configuration of Ytterbium in β‐YbAgGa2
Ulrich Schwarz Marcus Schmidt Roman Gumeniuk Walter Schnelle Michael Hanfland Konstantin Klementiev Yuri Grin 《无机化学与普通化学杂志》2004,630(1):122-126
Single‐phase polycrystalline samples of the intermetallic compound β‐YbAgGa2 were synthesized by inductive heating and subsequent annealing for eight weeks at 670 K. Magnetic properties were characterized by susceptibility measurements and indicated intermediate valence of ytterbium at ambient pressure. Angle‐dispersive X‐ray powder diffraction data of orthorhombic β‐YbAgGa2 indicate stability of the phase in the investigated pressure range from 0.1 MPa (ambient pressure) to 19 GPa. The pressure‐induced volume decrease is accompanied by an increase of the effective valence from 2.17 at ambient conditions to 2.71 at 16 GPa as evaluated by X‐ray absorption spectroscopy at the Yb LIII threshold. Analysis of the chemical bonding in β‐YbAgGa2 by integrating the electron density of the polyanion in basins as defined by the electron localization function results in an electron count Yb2.7+[(Ag0.2—)(Ga1(3b)1.0—)(Ga2(4b)1.5—)]. This finding is close to the expected values calculated by means of the Zintl rules and fits well the results of magnetic susceptibility measurements and XAS investigations. 相似文献
2.
Marc Dubois Belto Dieudonné Adel Mesbah Pierre Bonnet Malika El-Ghozzi Guillaume Renaudin Daniel Avignant 《Journal of solid state chemistry》2011,184(1):220-226
The unusual oxidation state +3 of the thorium has been stabilized into a lithium containing non-stoichiometric mixed-valence (III/IV) thorium fluorinated phase with formula Li2+xTh12F50 (0<x<1.8). This phase is closely related to the Li5.5Ce12F50 one, the structure of which has been determined from the combined single-crystal X-ray diffraction and high resolution synchrotron powder diffraction. In these phases, the Li+ ions can be divided into two groups and are located either in locked positions or in open channels of the three dimensional framework. The amount of Li+ ions in open channels can be variable, so that the afore mentioned single phase may be considered as an insertion compound. The Li+ insertion is accompanied by the simultaneous reduction of a part of the Th4+ ions, resulting in a mixed-valence III/IV thorium fluoride. The electrochemical insertion of Li+ ions into the open channels of the host matrix has been carried out at 60 °C, using an alkylcarbonate PC-LiClO4 1 M electrolyte. The Li+ and Th3+ contents, both in the starting composition and the Li+ inserted ones, were investigated by high resolution solid state 7Li NMR and EPR, respectively. 相似文献
3.
Jianwei Tong Florian Kraus Prof. Dr. Jürgen Köhler Arndt Simon Jia Liu Myung‐Hwan Whangbo 《无机化学与普通化学杂志》2011,637(9):1118-1121
Deep blue‐violet colored powder samples of Ag2ZnZr2F14 were synthesized by heating Zn(NO3)2·4H2O, Ag and ZrOCl2·8H2O at 300 °C under fluorine atmosphere. The crystal structure of Ag2ZnZr2F14 was refined from X‐ray powder diffraction data using the Rietveld method (C2/m, a = 9.0206(1) Å, b = 6.6373(1) Å, c = 9.0563(1) Å, β = 90.44(1)°, Z = 2). The structure is derived from the isotypic Ag3Zr2F14 by replacing only one of the two crystallographically different Ag2+ ions with Zn2+ ions, thus leading to discrete Ag2F7 dimers. These dimers are connected via nearly linear Ag–F···F–Ag bridges with short F···F distances of 2.33 Å to form two‐legged ladders. Magnetic susceptibility measurements and density functional calculations show that the two Ag2+ ions in each Ag2F7 dimer are strongly coupled antiferromagnetically. 相似文献
4.
Upendra Nath Dash Banka Behari Das Uttam Kumar Biswal Tapodhan Panda Narendra Kumar Purohit Dushmanta Kumar Rath Shubhankar Bhattacharya 《Thermochimica Acta》1983,63(3):261-276
The standard potentials of the silver-silver ion electrode in alcohol+water solvent mixtures containing 10 and 20 wt% methanol, ethanol, 1-propanol and 2-propanol have been determined from the electromotive force measurements of the cell Ag(s), AgCl(s), NaCl(c), NaNO3(c)// NaNO3(c), AgNO3(c), Ag(s) at seven different temperatures in the range 5–35°C. The standard potentials in each solvent have been represented as a function of temperature. The standard thermodynamic functions for the electrode reaction, the primary medium effects of various solvents upon Ag+, and the standard thermodynamic quantities for the transfer of 1 g-ion of Ag+ from water to the respective alcohol + water media have been evaluated and discussed in the light of ion-solvent interactions as well as the structural changes of the solvents. From the values of the standard potentials of the Ag/Ag+ and Ag/AgX, X? electrodes, the thermodynamic solubility product constants of silver chloride, silver bromide, silver iodide and silver thiocyanate have been determined in alcohol + water solvent mixtures at different temperatures. 相似文献
5.
Bernd G. Müller 《无机化学与普通化学杂志》1987,553(10):196-204
New Ternary Silver (II) Fluorides: Ag M F14 (MIV = Zr, Hf) Single crystals of deeply blue violet coloured fluorides Ag3IIM2IVF14 (MIV = Zr, Hf) have been obtained by heating powder samples under F2/N2 (1:2) at T ≈? 600°C. The isotypic compounds crystallizes monoclinic with a = 924.9, b = 668.6, c = 907.3 pm, β = 90.30° (Ag3Hf2F14) and a = 922.5, b = 667.6, c = 906.3 pm, β = 91.30° (Ag3Zr2F14) (Four circle diffractometer data, Philips PW 1100), spcgr. C2/m-C2h3 (No. 12), Z = 2. There are two different sorts of Ag2+:Ag(1) with coordination number C.N. [Ag(1)] = 4 + 2 and Ag(2) with C.N.[Ag(2)] = 4 + 4 against F?. Ag(1) can be substituted by Cu2+, Ni2+, Zn2+, Mg2+ (all of blue/red violet colour), Ag(2) by Ca2+, Cd2+, Hg2+ (bright green). From (preliminary) powder data CuAg2Zr2F14 with a = 912.3(4), b = 661.2(2), c = 899.4(2) pm, β = 90.70° (3) is isotypic, the other compounds seems to be of closely related type of structure. 相似文献
6.
Sayed Yahya Kazemi 《中国化学会会志》2008,55(5):1101-1106
A chloroform membrane system containing a given mixture of dibenzyldiaza‐18‐crown‐6 and palmetic acid was applied for transport of Pb2+ ions. The transport was capable of moving metal ions “uphill”. Thus, it was possible to follow the transfer of Pb(II) from the aqueous source phase to the organic layer and from the organic layer to the receiving phase. The effects of thiosulfate concentration in the receiving phase, palmetic acid and dibenzyldiaza‐18‐crown‐6 concentration in the organic phase on the efficiency of the transport system were examined. By using S2O32? ion as metal ion acceptor in the receiving phase, the amount of lead ion transport across the liquid membrane after 150 minutes is 96 ± 1.5%. The selectivity and efficiency of lead transport from aqueous solution containing Cu2+, Tl+, Ag+, Co2+, Ni2+, Mg2+, Zn2+, Hg2+, Cd2+, Ca2+ were investigated. In the presence of thiosulfate as a suitable masking agent in the source phase, the interfering effects of Ag+ and Cu2+ were diminished drastically. 相似文献
7.
The composition and the stability constants of the complexes formed between Ag(I) and ligands of the type where n,m = 2,2; 2,3; 2,4; 3,3; 3,4; 4,4, have been determined by a pH/pM-metric method at 25°C in a 0.5 M (K)NO3 medium. The determination of the stability constants proceeded by a combination of a graphical method and a least squares minimization procedure. The complex formation is discussed in comparison with silver complexes formed with S-containing mono-amines and in terms of the Taft σ*-parameters for the substituents. Below pH = 4, the protonated complexes AgLH23+ and AgL2H45+ are formed and the thioethergroup is the only coordinating centre. In neutral and alkaline medium there was evidence for the species AgLH2+, Ag2L2H24+, Ag2L2H3+, Ag2L22+, AgL2H34+, AgL2H2+, AgL2 + and Ag2L2+ in which Ag+? S and Ag+? NH2 bonds are involved. It is shown that in the Ag2L22+ and Ag2L2+ complexes the ligands effectively coordinate through all available donor centres. 相似文献
8.
G. H. Rounaghi M. H. Arbab-Zavar E. Fahmideh-Rad H. Sadeghian 《Russian Journal of Inorganic Chemistry》2010,55(10):1657-1665
The competitive bulk liquid membrane transport of Cr3+, Co2+, Cu2+, Zn2+, Cd2+, Ag+ and Pb2+ metal cations with a new synthetic sulfur donor acyclic ligand (pseudo-cyclic ionophore), i.e. 1-(2-[(2-hydroxy-3-phenoxypropyl)sulfanyl]ethylsulfanyl)-3-phenoxy-2-propanol;
(C20H26O4S2), was examined using some organic solvents as membranes. The membrane solvents include: chloroform (CHCl3), 1,2-dichloroethane (1,2-DCE), dichloromethane (DCM), nitrobenzene (NB), chloroform-nitrobenzene (CHCl3-NB) and chloroform-dichloromethane (CHCl3-DCM) binary mixtures. The transport process was driven by a back flux of protons, maintained by the buffering the source
and receiving phases with pH 5 and 3, respectively. The aqueous source phase consisted of a buffer solution (CH3COOH/CH3COONa) at pH = 5 and containing an equimolar mixture of these seven metal cations. The organic phase contained the acyclic
ligand, as an ionophore and the receiving phase consisted of a buffer solution (HCOOH/HCOONa) at pH = 3. For these systems
that displayed transport behaviour, sole selectivity for Ag+ cation was observed under the employed experimental conditions in this investigation. The amount of Ag+ transported follows the trend: 1,2-DCE > CHCl3 > DCM > NB in the bulk liquid membrane studies. The transport of the metal cations in CHCl3-NB and CHCl3-DCM binary solvents is sensitive to the solvent composition. The influence of the stearic acid, palmitic acid and oleic acid
in the membrane phase on the ion transport was also investigated. 相似文献
9.
Inés Sánchez-Movellán Dr. David Carrasco-Busturia Prof. Juan M. García-Lastra Dr. Pablo García-Fernández Prof. José A. Aramburu Prof. Miguel Moreno 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(43):e202200948
The pressure-induced switch of the long axis of MnF63− units in the monoclinic Na3MnF6 compound and Mn3+-doped Na3FeF6 is explored with the help of first principles calculations. Although the switch phenomenon is usually related to the Jahn-Teller effect, we show that, due to symmetry reasons, it cannot take place in 3dn (n=4, 9) systems displaying a static Jahn-Teller effect. By contrast, we prove that in Na3MnF6 the switch arises from the anisotropic response of the low symmetry lattice to hydrostatic pressure. Indeed, while the long axis of a MnF63− unit at ambient pressure corresponds to the Mn3+−F3− direction, close to the crystal c axis, at 2.79 GPa the c axis is reduced by 0.29 Å while b is unmodified. This fact is shown to force a change of the HOMO wavefunction favoring that the long axis becomes the Mn3+−F2− direction, not far from crystal b axis, after the subsequent relaxation process. The origin of the different d-d transitions observed for Na3MnF6 and CrF2 at ambient pressure is also discussed together with changes induced by pressure in Na3MnF6. The present work opens a window for understanding the pressure effects upon low symmetry insulating compounds containing d4 or d9 ions. 相似文献
10.
Ekta Nag Sridhar Battuluri Dr. Kartik Chandra Mondal Dr. Sudipta Roy 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(64):e202202324
Silver clusters are attractive candidates for their promising optical properties, and biomedical activities. Herein, we report on the first syntheses and isolation of three homo-/mixed-valence silver nanoclusters (NCs) with Ag12Cl3, Ag29, and Ag8 cores [((cAAC)P)6Ag12Cl3](OTf)3 ( 1 ), [((cAAC)P)6Ag29] ( 2 ), and [((cAAC)P)4Ag8] ( 3 ) having three-/twofold symmetry, employing cyclic alkyl(amino) carbene (cAAC)-supported phosphinidenide (cAACP−) as the π-accepting stabilizing ligand. The average diameters of Ag NCs 1 , and 2 are approximately 1.6 to 2 nm. The redox non-innocent mono-atomic phosphorus anions (P−) anchored with cAAC ligands are generated in situ by the reaction of AgOTf with a boryl-phosphaalkene (cAAC)P−B(NiPr2)2 through cleavage of the P−B bond with the help of a triflate anion (OTf−) as a weak nucleophile. Equivalent number of the (cAAC)P− anions generated in situ are oxidized to produce the corresponding bis-phosphinidene (cAAC)2P2 leading to the generation of Ag0 ions in solution for the formation of the unprecedented mixed-valence Ag NC 2 . Complex 3 is achieved by treating potassium phosphinidenide cAACPK with AgNTf2. The ligand field and the steric hindrance of the (cAAC)P units play crucial roles in stabilizing complexes 1 – 3 , further providing a three- ( 1 , 2 )/two- ( 3 ) fold stand. The Ag12Cl3 NC ( 1 ) with a tricationic core [AgI12Cl3] was found to be diamagnetic, and fluorescent, emitting green light at 563 nm when excited at 400 nm. In contrast, the neutral Ag29 ( 2 ) and Ag8 ( 3 ) clusters were found to be paramagnetic, and NMR silent showing characteristic EPR signals for Ag0 at room temperature. 相似文献
11.
M. Izadyar G. H. Rounaghi S. Tarahomi M. Mohajeri 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2013,87(12):2039-2043
Conductometric titrations have been performed in acetonitrile-ethylacetate (AN-EtOAc) binary solutions at 288, 298, 308, and 318 K to obtain the stoichiometry, the complex stability constants and the standard thermodynamic parameters for the complexation of Cd2+, Ni2+, and Ag+ cations with 4,13-didecyl-1,7,10,16-tetraoxa-4,13-diazacyclooctadecane (cryptand 22DD). The stability constants of the resulting 1: 1 complexes formed between the metal cations and the ligand were determined by computer fitting of the conductance-mole ratio data. There is a non-linear relationship between the logK f values of complexes and the mole fraction of ethylacetate in the mixed solvent system. In addition, the conductometric data show that the stoichiometry of the complexes formed between the Cd2+, Ni2+, and Ag+ cations with the ligand changes with the nature of the solvent. The standard enthalpy and entropy values for the 1: 1 [ML] complexation reactions were evaluated from the temperature dependence of the formation constants. Thermodynamically, the complexation processes of the metal cations with the C22DD, is mainly entropy governed and the values of thermodynamic parameters are influenced by the nature and composition of the binary mixed solvent solutions. 相似文献
12.
Sodium-dicyclohexyl- 18-crown-6 complex cation was used as carrier for the uphill transport of zinc as Zn(SCN)42? complex anion. By using L-cysteine as a metal ion acceptor in the receiving phase at the optimized pH of 7.6, the amount of zinc transport through the liquid membrane after 90 min was 97.2 ± 1.0%. The selectivity and efficiency of zinc transport from aqueous solutions containing equimolar mixtures of Ag+, Cd2+ Co2+, Cu2+, Fe2+, Ni2+, Pb2+, Pd2+, Sr2+, Bi3+, Cr3+ and Fe3+ ions was investigated. In the presence of NH2OH.HCl as a suitable masking agent in the source phase, the interfering effect of Cu2+ and Pb2+ ions was diminished drastically. 相似文献
13.
Matthias Weil PD Dr. 《无机化学与普通化学杂志》2007,633(8):1217-1222
Single crystals of a third modification of Ag2Te2O6 (denoted as Ag2Te2O6–III) and of Ag4TeO5 have been obtained as minor by‐products during hydrothermal phase formation experiments in the system Ag‐Hg‐Te‐O. The crystal structure of Ag2Te2O6–III (P21/c, Z = 4, a = 6.4255(10), b = 6.9852(11), c = 13.204(2) Å, β = 90.090(3)°, 1885 independent reflections, R[F2 > 2σ(F2)] = 0.0334, wR2(F2 all) = 0.0817) comprises tellurium in oxidation states +IV and +VI and is topologically related to the structure of the Ag2Te2O6–I modification, which consists of similar layers and interjacent layers of Ag+ cations. Ag4TeO5 (C2/c, Z = 8, a = 16.271(2), b = 6.0874(10), c = 11.4373(16) Å, β = 106.730(10)°, 2372 independent reflections, R[F2 > 2σ(F2)] = 0.0288, wR2(F2 all) = 0.0737) is made up of a layer‐like arrangement of isolated [TeVI2O10] double octahedra and of Ag+ cations situated both in layers parallel and inside the layers of the anionic moieties. 相似文献
14.
Gholam Hossein Rounaghi Razyeh Sanavi Khoshnood Mohammad Hossein Arbab Zavvar 《Journal of inclusion phenomena and macrocyclic chemistry》2006,54(3-4):247-252
The complexation reactions between Mg2+, Ca2+, Ag+ and Cd2+ metal cations with N-phenylaza-15-crown-5 (Ph-N15C5) were studied in acetonitrile (AN)–methanol (MeOH), methanol (MeOH)–water (H2O) and propanol (PrOH)–water (H2O) binary mixtures at different temperatures using the conductometric method. The conductance data show that the stochiometry of all of the complexes with Mg2+, Ca2+, Ag+ and Cd2+ cations is 1:1 (L:M). The stability of the complexes is sensitive to the solvent composition and a non-linear behaviour was observed for variation of log K
f of the complexes versus the composition of the binary mixed solvents. The selectivity order of Ph-N15C5 for the metal cations in neat MeOH is Ag+>Cd2+>Ca2+>Mg2+, but in the case of neat AN is Ca2+>Cd2+>Mg2+>Ag+. The values of thermodynamic parameters (ΔH
c
o
, ΔS
c
o
) for formation of Ph-N15C5–Mg2+, Ph-N15C5–Ca2+, Ph-N15C5–Ag+ and Ph-N15C5–Cd2+ complexes were obtained from temperature dependence of stability constants and the results show that the thermodynamics of complexation reactions is affected by the nature and composition of the mixed solvents. 相似文献
15.
Achim Müller Sergei Talismanov Paul K?gerler Hartmut B?gge Marc Schmidtmann Boris Tsukerblat 《Journal of Cluster Science》2005,16(3):391-396
A planar network consisting of {Mo17(NO)2}3{MoV
2}3{Fe6III} cluster entities that are interlinked to layers via {FeII(H2O)4}2+ groups is formed stepwise from building units. The corresponding mixed-valence compound exhibits a variety of different formal
oxidation states: {MoNO}3+, MoV, MoVI, FeII, and FeIII. This compound also represents an extension of building-block hierarchy from the molecular level to extended networks. 相似文献
16.
Gh. H. Rounaghi A. Soleamani K. R. Sanavi 《Journal of inclusion phenomena and macrocyclic chemistry》2007,58(1-2):43-48
The complexation reactions between Ag+, Hg2+ and Pb2+ metal cations with aza-18-crown-6 (A18C6) were studied in dimethylsulfoxide (DMSO)–water (H2O) binary mixtures at different temperatures using the conductometric method. The conductance data show that the stoichiometry
of the complexes in most cases is 1:1(ML), but in some cases 1:2 (ML2) complexes are formed in solutions. A non-linear behaviour was observed for the variation of log K
f of the complexes vs. the composition of the binary mixed solvents. Selectivity of A18C6 for Ag+, Hg2+ and Pb2+ cations is sensitive to the solvent composition and in some cases and in certain compositions of the mixed solvent systems,
the selectivity order is changed. The values of thermodynamic parameters (ΔH
co, ΔS
co) for formation of A18C6–Ag+, A18C6–Hg2+ and A18C6–Pb2+ complexes in DMSO–H2O binary systems were obtained from temperature dependence of stability constants and the results show that the thermodynamics
of complexation reactions is affected by the nature and composition of the mixed solvents. 相似文献
17.
Crystal structure of AgIIF[AgIIIF4] For the first time dark brown single crystals of mixedvalent AgF[AgF4] were isolated under solvothermal conditions out of anhydrous HF/F2. The compound crystallizes in a new type of structure, triclinic with a = 499.9(2) pm, b = 1108.7(5) pm, c = 735.7(3) pm, α = 90.05(3)°, β = 106.54(4)°, γ = 90.18(4)°, spcgr. P1¯ — Ci1 (No. 2) and Z = 4. 相似文献
18.
《Journal of membrane science》1999,157(2):171-176
The facilitated transport of Au(III) from cyanide solutions through a bulk liquid membrane is reported. The organic phase consisted of a chloroform solution containing Victoria blue dye as the Au(CN)−4 carrier. The effects of pH of source phase, potassium cyanide concentration in source phase, Victoria blue concentration in the organic phase and sodium hydroxide in the receiving phase on the efficiency of transport process were examined. Under optimum conditions the extent of Au(CN)−4 transport across the liquid membrane was about 97% after 180 min. The carrier can selectively and efficiently transport Au(CN)−4 ion from the aqueous solutions containing other cations such as alkali and alkaline earth, Zn2+, Pb2+, Cu2+, Cd2+, Hg2+, Ag+, Co2+, Fe2+, Pt2+, Pd2+ and Ni2+. 相似文献
19.
E. N. Ushakov L. G. Kuz’mina A. I. Vedernikov M. S. Kapichnikova J. A. K. Howard M. Wörner A. M. Braun M. V. Alfimov S. P. Gromov 《Russian Chemical Bulletin》2006,55(1):94-100
The structures of new butadienyl dyes of the benzothiazole series containing the dithia-15-crown-5 (2a) or dithia-18-crown-6 (2b) fragments were established by X-ray diffraction. Complexation of dyes 2a,b with Hg2+, Pb2+, Cd2+, Ag+, Zn2+, and alkaline-earth cations in aqueous-acetonitrile solutions was studied by spectrophotometry. At a high percentage of water
in solutions (P
w ≈ 50%), these dyes have a very low ability to bind Pb2+ cations (logK < 2) and virtually do not bind Cd2+, Zn2+, and alkaline-earth cations. At the same time, these dyes form stable 1: 1 complexes with Hg2+ and Ag+ cations at all P
w. The stability constants of complexes with the Ag+ cation increase with increasing P
w because the free energy of hydration of this cation is much lower than the free energy of solvation in acetonitrile. In the
P
w range from 0 to 75%, the stability constants of the complexes of dyes 2a,b with the Hg2+ cation are larger than those of the corresponding complexes with the Ag+ cation by more than four orders of magnitude.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 90–96, January, 2006. 相似文献
20.
Long-lived (hours to days) silver clusters, Ag 4 2+ , Ag 4 + , Ag 8 2+ , etc., are formed upon the radiation-induced reduction of Ag+ ions in aqueous solutions containing sodium polyphosphate. The efficiency of the cluster formation decreases and the stability of the clusters increase with a rise in the concentration of the polymeric stabilizer. In the course of the aggregation of clusters, their sizes increase, quasi-metallic particles emerge, and the process terminates with the formation of silver nanoparticles. The mechanism of silver nucleation upon the radiation-induced reduction of silver ions in aqueous solutions is discussed. 相似文献