共查询到20条相似文献,搜索用时 15 毫秒
2.
Electron propagator theory (EPT) is applied to calculating vertical ionization energies of the anions F −, Cl −, OH −,SH −, NH 2−, PH 2− and CN −. Third-order and outer valence approximation (OVA) quasiparticle calculations are compared with ΔMBPT(4) (MBPT, many-body perturbation theory) results using the same basis sets. Agreement with experiment is satisfactory for EPT calculations except for F − and OH −, while the ΔMBPT treatments fail for CN −. EPT(OVA) estimates are reliable when the discrepancy between second- and third-order results is small. Computational aspects are discussed, showing relative merits of direct and indirect methods for evaluating electron binding energies. 相似文献
3.
Based on detailed bonding analyses on the fluxional behaviors of planar B 19−, tubular Ta@B 20−, and cage-like B 39−, we propose the concept of fluxional bonds in boron nanoclusters as an extension of the classical localized bonds and delocalized bonds in chemistry. © 2018 Wiley Periodicals, Inc. 相似文献
4.
The electrophoretic behavior of twenty anions has been studied on silica gel-G, titanium (IV) tungstate and silica gel-G- titanium (IV) tungstate admixture layers using 0.1 M solutions of oxalic acid, citric acid, tartaric acid, succinic acid and acetic acid as background electrolyte. The mechanism of migration is explained in terms of adsorption and the solubility of various sodium or potassium salts of the anions in water. Titanium (IV) tungstate behaves only as an adsorbent and not as an ion exchanger. Being a cation exchanger, there is no exchange phenomenon occurring with anions. The migration of halides increase linearly with an increase in the bare ion radii of these ions. Differential migration of the anions on silica gel-G layers led to binary, ternary and quaternary separations of similar anions such as F− – Cl− – Br− – I−, I− – IO3− – IO4−, BrO3− – IO3− and Fe(CN)63− – Fe(CN)64−. The two cyanoferrate ions are separated from industrial waste water and from fixer and bleach solutions. The migration of anions has also been found to be in accordance with their lyotropic numbers. 相似文献
5.
A new type of negative ion photoelectron spectrometer which utilizes time-of-flight for both ion mass selection and photoelectron energy analysis is described and demonstrated on the 532 nm photodetachment of the well-known O − and O −2 ions as well as the O −4 cluster ion. Photoelectron spectra of O −4 at 355 and 532 nm depend on laser power, suggesting that photodissociation competes with photodetachment at both wavelengths. 相似文献
6.
The dissolution behaviour of cellulose in low temperature molten salts was investigated. Depending on the chosen anions in the melt, cellulose shows different reaction behaviour in different Li +containing melts. Dissolution of the polymer was observed in molten LiClO 43H 2O and molten LiI2H 2O. In the hydrated melts of LiCH 3COO2H 2O and LiNO 33H 2O a fine distribution of cellulose was stated. Cellulose can be regenerated by cooling the melt and removing the salt by dissolution in water.The structure of the recrystallized product is determined by the used low temperature molten salt. 相似文献
8.
The binding of SO 2 on gas-phase gold cluster anions, Au N−, and their hydroxide counterparts, Au NOH −, have been studied using density functional theory combined with flow reactor/time-of-flight mass spectrometry techniques. SO 2 is adsorbed on all of the Au N− and Au NOH − clusters ( N = 1-8) and the hydroxide clusters are more active than the bare anionic clusters. Successive additions of SO 2 molecules (up to four) have been analyzed. In all cases, anionic clusters are shown to bind multiple SO 2 molecules. Theoretical analyses are in agreement with the experimental results, showing that the addition of more than one molecule is thermodynamically favorable. Larger clusters do not necessarily absorb more molecules, as different SO 2 binding motifs on these clusters are present. These results provide important insight for the potential use of these anionic clusters as SO 2 hunters. 相似文献
10.
Hetero polyanions, namely, P 2W 17O 61
10–, P 2W 18O 62
6– and SiW 11O 39
8– were extracted by TBP/dodecane from HNO 3 or HCl solution, as H 10P 2W 17O 61 in the case of P 2W 17O 61
10–. The distribution ratio of P 2W 17O 61
10– depended on both H + concentration and ionic strength of aqueous solution, and free-TBP concentration in organic solution. Experimental equation was established for predicting the distribution ratio of P 2W 17O 61
10– in nitrate system. 相似文献
11.
The crystal structures of (CNSSS) 2(AsF 6) 2, (CNSSS) 2(SbF6) 2, and two phases of (CNSSS) 2(Sb 2F 11) 2 have been determined. The AsF 6 ?, SbF 6 ?, and α-Sb 2F 11 ? salts crystallize as reddish-brown plates whereas the β-Sb 2F 11 ? salt crystallizes as green rods. The dication ß+SSSNCCNSSS +ß (1 2+) is the same in all four structures and consists of two 7π rings linked by a sp 2-sp 2 C-C bond (1.462 Å in 1 (AsF 6) 2). The packing in the four structures is similar with stacks of dications along the a-axis and alternating sheets of dications and anions lying in the bc-plane. The differences in the dication-dication contacts is reflected in the variable temperature magnetic data. 相似文献
12.
Apparent molar heat capacities and volumes have been determined for aqueous solutions of the mixed electrolytes Na 5DTPA + NaOH, Na 3CuDTPA + NaOH, and NaCu 2DTPA + NaOH, and the single electrolyte Na 3H 2DTPA (DTPA=diethylenetriaminepentaacetic acid) at temperatures from 10 to 55°C. The experimental results have been analyzed in terms of Young's rule with the Guggenheim form of the extended Debye–Hückel equation and the Pitzer ion-interaction model. These calculations led to standard partial molar heat capacities and volumes for the species H 2DTPA 3–(aq), DTPA 5–(aq), CuDTPA 3–(aq), and Cu 2DTPA –(aq) at each temperature. The partial molar properties at 0.1 m ionic strength were also calculated. The standard partial molar properties were extrapolated to elevated temperatures with the revised Helgeson–Kirkham–Flowers (HKF) model. Values for the partial molar heat capacities from the HKF model have been combined with the literature data to estimate the ionization constants of H 2DTPA 3–(aq) and the formation constant of the CuDTPA 3–(aq) copper complex at temperatures up to 300°C. 相似文献
13.
Adsorption of Cl ?, Br ?, and I ? (Hal ?) ions from 0.1 M solutions in methanol (MeOH) is studied on the liquid renewable Ga, (In-Ga), and (Tl-Ga) electrodes by the methods of differential capacitance and jet electrode. It is shown that the adsorption parameters and the series of surface activity of halide ions in MeOH essentially depend on the metal nature. On the (In-Ga) and (Tl-Ga) electrodes, as well as on the Hg electrode, the surface activity of halide ions increases in the series: Cl ? < Br ? < I ?; on the Ga electrode, it varies in another series: Br ? < Cl ? < I ?. The data for the Ga/MeOH interface support the result, which was first obtained on the Ga/ N-methyl formamide ( N-MF) interface, that the effect of inversion of surface activity series can be observed not only in the aprotic solvents, but also in the protic solvents. The data, which were obtained in MeOH, are compared with the corresponding data, which were obtained in N-MF, dimethyl formamide (DMF), acetonitrile (AN), and water. For Ga, (In-Ga), and (Tl-Ga) electrodes, the adsorption of Hal ? varies in the series: H 2O < MeOH ≈ N-MF < DMF < AN. The data obtained in MeOH indicate that the energy of metal-Hal ? interaction (Δ G M-Hal) increases in the series (Tl-Ga) < (In-Ga) < Ga as the electronic work function increases. This is in agreement with the data, which were obtained in other solvents, and is the evidence for the donor-acceptor nature of metal-Hal ? interaction, where the Hal ? ions are the donors of electron pair with respect to the metal. 相似文献
14.
Absolute Raman scattering activities of aqueous solutions of sodium bromate and lithium iodate have been measured against NaClO 4 as an external standard. Electro-optical parameters (EOPs) for the BrO and IO bonds were calculated. Equilibrium bond polarizabilities were estimated from refractive index measurements in connection with Raman intensities of the bending modes. Relations between Bragg—Slater radii and EOPs are discussed. EOPS calculated from experimental data are compared with those from ab initio calculations. 相似文献
15.
The solid phase thermal deaquation-anation of [Rh(NH 3) 5(H 2O)]X 3 (X = Cl −, Br −, I −) has been investigated by means of isothermal TG measurements applying all the principal g(α) expressions (0.8 ⩾ α ⩾ 0.2). The values found for the activation energy are low: ≈ 95 kJ mol −1 for the Cl − compound; ~105 kJ mol − for the Br − compound and ≈110 kJ mol −1 for the I − compound. These data permit the assignment of the deaquation-anation mechanism of the S N1 dissociative type, involving a square-based pyramid activated complex and elimination of water as Frenkel defects. These values are similar to those reported for the Co(III) and Ir(III) analogues, indicating that the Dq parameter is not the principal contribution to the activation energy of the dehydration-anation process. 相似文献
16.
Reaction of uranium salts with several lacunary polyoxotungstate anions yields four new heteropolyanion assemblies in which the uranium atoms occupy pentagonal bipyramidal coordination polyhedra. Treatment of A, -[SiW 9O 34] 10– with UO 2(NO 3) 2 leads to Na 14[Na 2(UO 2) 2(SiW 9O 34) 2]38H 2O ( 1, Monoclinic, P2 1/c, a=16.5719(8) Å, b=14.1689(7) Å, c=21.2528(10) Å, =111.6670(10)°, V=4786.6(4) Å 3, Z=2) which proves to be isostructural with the analogous derivative of [PW 9O 34] 9– reported previously. Solutions of 1 exhibit the 5-line W-NMR spectrum expected for the structure of C
i
point symmetry. The salt (NH 4) 17[(UO 2) 3(H 2O) 4As 3W 26O 94]16H 2O ( 2, Orthorhombic, Pnma, a=40.1747(2) Å, b=18.25840(10) Å, c=18.0817(2) Å, V=13263.4(2) Å 3, Z=4) was isolated in 64% yield from a reaction of UO 2(NO 3) 2 with B, -[AsW 9O 33] 9–. The structure of the anion in 2 has C
s
symmetry and contains one -AsW 9O 33 and two novel -AsW 8O 30 units linked by the UO 2+
2 groups; an additional WO 6 links the two AsW 8 fragments. Spectrophotometric titration of UCl 4 with the sodium salt of [As 4W 40O 140] 28– indicated the formation of a 4:1 U:As 4W 40 complex. During attempts to isolate a crystalline product from this reaction the uranium became oxidized and a guanidinium salt of [Na(UO 2) 3(OH)(H 2O) 6As 4W 40O 140(WO)] 18– ( 3, Orthorhombic, Fdd2, a=54.848(3) Å, b=80.809(4) Å, c=20.2874(2) Å, V=89919(7), Z=16) was isolated. The partially disordered structure of 3 shows the S 2 and adjacent sites of the lacunary As 4W 40 anion to be occupied by three UO 5 and one WO 5 polyhedra. A tetrameric assembly of -SiW 10 units linked by UO 2+
2 groups occurs in [{M(OH 2)} 4(UO 2) 4(OH) 2(SiW 10O 36) 4] 22– (lithium salt, M=Na, 4a, tetragonal, P4 2/nmc, a= b=26.5285(2) Å, c=15.0463(2) Å, V=10589.0(2) Å 3, Z=2; sodium-potassium salt, M=K, 4b, orthorhombic, Fddd, a=24.180(5) Å, b=31.696(6) Å, c=58.012(12) Å, V=44460(15) Å 3, Z=8). Tungsten-183 NMR spectra show the slow transformation of the expected 5-line (1:1:1:1:1) spectrum of 4a to a new species giving a 6-line spectrum (2:2:2:1:2:1). The latter complex has not been successfully isolated. 相似文献
17.
Codeposition of Na and NH 3 at ≈ 35 K gives rise to an absorption band at ≈ 16950 cm −1 with a positive MCD å term. This band is assigned to the 1S → 1P transition of Na − marking the first direct evidence for the existence of an alkalide in NH 3. The absorption and MCD of the solvated electron band are also observed in the near infrared at ≈ 8000 cm −1. 相似文献
19.
Lifetimes of NF b 1Σ + (2.33 ms) and a 1Δ (2.85 s) in solid argon have been determined by pulsed laser excitation of the b state. The integrated (0,0) band intensities of the b→X, b→a, and a→X transitions are 1.00, 2.9±0.6, and 2.7±0.6, in relative units. It is concluded that cascading from b 1Σ + to a 1Δ is purely radiative within these error limits. While the b→X and a→X transition rates compare favorably with gas-phase data and theoretical calculations, the b→a transition rate is enhanced by four orders of magnitude in the matrix. 相似文献
|