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1.
A method of analysing the differential capacity developed by Amokrane and Badiali is applied to investigations of the structure of the interface between mercury and simple aliphatic alcohols. Capacitance data for methanol, ethanol, n-propanol and n-butanol are discussed. The solvent contribution Cs is obtained by subtracting the contribution CM due to the metal from the inner layer capacitance Ci according to the procedure proposed by Amokrane and Badiali. The CS values are found to be very similar for all aliphatic alcohols studied. The CSM curves have a similar shape with a single maximum at a positive charge density and a characteristic inflection at a negative charge density. The effect of ions in the various supporting electrolytes on the CSM profiles was also studied.  相似文献   

2.
The geometries of 7-azaindole (7AI), its tautomer (7AT), and 7AI–H2O and 7AT–H2O complexes were optimised in the ground state and some low-lying singlet excited states using the 3-21G basis set. Differences of total energies of the optimised ground and excited states and the vertical excitation energies of these systems were used to explain the observed electronic spectra. Effect of solvation of these systems in bulk water was studied using the polarized continuum model (PCM). The mode of binding of a water molecule in the S2(n–π*) excited state of 7AI was found to be quite different from those in its ground and π–π* excited states. It is shown that crossing of the lowest two singlet excited-state potential surfaces S1(π–π*) and S2(n–π*) of 7AI occurs in the vapour phase under geometry relaxation while on interaction with water, the S2(n–π*) excited state is raised up appreciably going even above the S3(π–π*) excited state. Ground- and excited-state molecular electrostatic potential mapping was carried out, which led to valuable information regarding the nature of excited states of the above-mentioned systems.  相似文献   

3.
A new kind of self-assembled monolayer (SAM) formed in aqueous solution through the pre-formed inclusion complexes (abbreviated CD · Cn) between α, β-cyclodextrins (CDs) and alkanethiols (CH3(CH2)n−1)SH, n = 10, 14 and 18) was prepared successfully on gold electrodes. High-resolution 1H NMR was used to confirm the formation of CD · Cn. X-ray photoelectron spectroscopy, cyclic voltammetry and chronoamperometry were used to characterize the resulting SAMs (denoted as MCD·Cn). It was found that MCD·Cn were more stable against repeated potential cycling in 0.5 M H2SO4 than SAMs of CH3(CH2)n−1SH (denoted as MCn), with a relative sequence of Mβ−CD·Cn > Mα−CD·Cn > MCn. In addition, an order of blocking the electron transfer between gold electrodes and redox couples (both Fe(CN)36 and Ru(NH3)346) in solution, MCD·C10 > MCD·C14 > MCD·C18, was observed. A plausible explanation is provided to elucidate some of the observations.  相似文献   

4.
The ground-state rotational spectra of two isotopomers 15N2I35Cl and 15N2I37Cl of a complex formed between dinitrogen and iodine monochloride were observed by pulsed-jet, Fourier-transform microwave spectroscopy. The spectra were interpreted on the basis of a linear equilibrium geometry with the weak bond formed between N and I. The spectroscopic constants B0, DJ, χaa(I), χaa(Cl) and Mbb(I) were determined for each isotopomer and various models for the complex were employed to yield the distance r(NI)=3.180(2)Å, the intermolecular stretching force constant kσ=5.37(3) Nm−1, and the inter- and intramolecular electronic transfers δi=0.004(3) and δp(Cl)=0.018(2).  相似文献   

5.
A self-consistent-field-Xα-scattered-wave molecular orbital calculation was carried out on the [CpMoS(μ-S)]2(Cp = η5-C5H5) complex. The calculated results were used to rationalize the observed photochemical isomerization of the title complex to [CpMo(μ-S)][μ-S2]. It is proposed that a terminal sulfur (St) → Mo charge-transfer excitation is responsible for the isomerization, which is an intramolecular redox; i.e. Mo(V) is reduced to Mo(IV) and S2− is oxidized to S22− , a result consistent with the charge-transfer character of the excitation. Specifically, the transition responsible for the isomerization is proposed to be 16bu → 18ag (1Ag1Bu). The 18ag orbital is primarily Mo in character but it is also Mo---St π-antibonding; cleavage of the Mo---St π-bond facilitates the isomerization.  相似文献   

6.
Experimental data related to the potential dependence of nonlinear characteristics of the electrical double layer at a liquid In–Ga electrode in aqueous solutions of a symmetrical surface-inactive electrolyte are obtained for the first time. It is shown that, as opposed to polycrystalline Cd and Pb electrodes, on a liquid (atomically smooth) In–Ga electrode, as on Hg, there is a clear intersection of the potential dependences of a nonlinear signal for different concentrations of a 1–1-valence surface-inactive electrolyte at one point. The intersection point exactly corresponds to the potential of zero charge of an electrode undistorted by specific adsorption of ions. It is established that, when estimating hydrophilicity of metals by a nonlinear impedance method, most information is provided by the region of average negative charges, rather than by the region near zero charge. It is shown that, as opposed to a linear impedance method, the nonlinear impedance method makes it possible to determine, directly from experiment, quantities that directly characterize the metal–solvent chemisorption interaction in a pure form; at the same time, these quantities are criteria of lyophilic nature of metals. Quantities that characterize the metal–solvent chemisorption interaction, obtained by the linear and nonlinear impedance methods are in good agreement, which confirms the validity of the approach we proposed earlier for separating the difference between reciprocal capacitances of the inner part of the electrical double layer on Hg and metal M, Hg M C -1 i= 1/C Hg i– 1/C M iinto physical (Hg M C –1)physand chemical constituents. This coincidence also confirms correctness of numerical values obtained earlier for quantities (Hg M C –1)phys.  相似文献   

7.
In the present work lithium (sodium) vanadium tungsten oxides with brannerite structure is refined by the Rietveld method (space group C2/m, Z=2). IR and Raman spectroscopy was used to assign vibrational bands and determine structural particularities. The diffuse reflectance spectra allow to calculate bandgap for MIVWO6(MI – Li, Na). The temperature dependences of heat capacity have been measured first in the range from 7 to 350 K for these compounds and then between 330 and 640 K, respectively, by precision adiabatic vacuum and dynamic calorimetry. The experimental data were used to calculate standard thermodynamic functions, namely the heat capacity Cpo(T), enthalpy Ho(T)−Ho(0), entropy So(T)−So(0) and Gibbs function Go(T)−Ho(0), for the range from T→0 to 640 K. The differential scanning calorimetry was applied to measure decomposition temperature of compounds under study.  相似文献   

8.
The molecular structure and benzene ring distortions of ethynylbenzene have been investigated by gas-phase electron diffraction and ab initio MO calculations at the HF/6-31G* and 6-3G** levels. Least-squares refinement of a model withC 2v, symmetry, with constraints from the MO calculations, yielded the following important bond distances and angles:r g(C i -C o )=1.407±0.003 Å,r g(C o -C m )=1.397±0.003 Å,r g(C m -C p )=1.400±0.003 Å,r g(Cr i -CCH)=1.436 ±0.004 Å,r g(C=C)=1.205±0.005 Å, C o -C i -C o =119.8±0.4°. The deformation of the benzene ring of ethynylbenzene given by the MO calculations, including o-Ci-Co=119.4°, is insensitive to the basis set used and agrees with that obtained by low-temperature X-ray crystallography for the phenylethynyl fragment, C6H5-CC-, in two different crystal environments. The partial substitution structure of ethynylbenzene from microwave spectroscopy is shown to be inaccurate in the ipso region of the benzene ring.  相似文献   

9.
An idea was presented of treating the chromatographed substance as a “solute,” and the chromatographic system, composed of the stationary and the mobile phase as a “solvent.” Moreover the concept of “local equilibrium” was introduced, allowing to regard a given chromatographic spot as a “binary solution.” Thus a possibility arose to apply the classical thermodynamic approach, normally used for binary solutions, and namely: μi = μi + RT ln xiƒi, where μi—chemical potential of the “i”-th compound in the solution, μi—chemical potential of the pure “i”-th compound, xi-molar fraction of the “i”-th compound, ƒi—its activity coefficient, in a modified form, suitable for the chromatographic purpose.  相似文献   

10.
Reactions of triangular telluride-bridged Mo and W clusters [M33-Te)(μ2-Te2)3(dtp)3]+ (M = Mo, W; dtp = (EtO)2PS2) with S2Cl2 or Br2 lead to Te/S exchange in the Te2 ligands, with the formation of complexes with a novel TeS2− ligand. Reaction of [W33-Te)(μ2-Te2)3(dtp)3]+ with Br2 or S2Cl2 gives a mixture of complexes formulated as [W3Te4.25S2.75(dtp)3]+ and [W3Te4.30S2.70(dtp)3]+, respectively, on the basis of X-ray structural analysis. Reaction of the Mo homolog, namely [Mo33-Te)(μ2-Te2)3(dtp)3]+, with S2Cl2 gives rise to [Мо3Te4.74S2.26((EtO)2PS2)3]+. Electrospray ionization mass spectrometry (ESI-MS) complements the information gathered from X-ray analysis regarding the degree of Te by S substitution; moreover, detailed insights on the regioselectivity of such replacement are also obtained from ESI-MS analysis. These experimental evidences indicate that Te by S replacement in W complexes display high regioselectivity (as evidenced by the exclusive formation of a W3Te4S34+ core), the equatorial Te ligands being preferentially replaced over the Teax and μ3-Te ligands. Conversely, for the Mo homologs, a broad distribution of Mo3Te7−xSx4+ cluster species ranging from x = 0 to 6 is observed. Bond distance analysis as well as crystal packing trends as a function of the cluster core M3Te7−xSx4+ (M = Mo, W; x = 0–6) composition are also reported.  相似文献   

11.
Trinuclear silver(I) thiolate and silver(I) thiocarboxylate complexes [Ag3(μ‐dppm)3n‐SR)2](ClO4) [n = 2, R = C6H4Cl‐4 ( 1 ) and C{O}Ph ( 2 ); n = 3, R = tBu ( 3 )], pentanuclear silver(I) thiolate complex [Ag5(μ‐dppm)43‐SC6H4NO2‐4)4](PF6) ( 4 ), and hexanuclear silver(I) thiolate complexes [Ag6(μ‐dppm)43‐SR)4]Y2 [Y = ClO4, R =C6H4CH3‐4 ( 5 ) and C10H7 (2‐naphthyl) ( 7 ); Y = PF6, R = C6H4OCH3‐4( 6 )], were synthesized [dppm = bis(diphenylphosphanyl)methane] and their crystal structures as well as photophysical properties were studied. In the solid state at 77 K, trinuclear silver(I) thiolate and silver(I) thiocarboxylate complexes 1 and 2 exhibit luminescence at 470–523 nm, tentatively attributed to originate from the 3IL (intraligand) of thiolate or thiocarboxylate ligands, whereas hexanuclaer silver(I) thiolate complexes 5 and 7 produce dual emission, in which high‐energy emission is tentatively attributed to come from the 3IL of thiolate ligands and low‐energy emission is tentatively assigned to come from the admixture of metal ··· metal bond‐to‐ligand charge‐transfer (MMLCT) and metal‐centered (MC) excited states.  相似文献   

12.
Free P(SMe)3 molecule was studied by gas electron diffraction (GED) and by B3PW91/6-311+G* (DFT) and MP2/6-31+G* calculations. Each conformer is characterized by three dihedral angles τ(CSPlp), where lp denotes the direction of the lone electron lone pair on the P atom. DFT calculations indicate that the most stable conformer is an anti,gauche+,gauche- (ag+g-) conformer of C s symmetry; the next are the ag+g+ (ΔE = 2.5 kJ mol−1), g+g+g+ (ΔE = 5.2 kJ mol−1), and aa+g+ (Δ E = 12.5 kJ mol−1) conformers. The MP2 calculations give the similar order, with the relative energies of 0.3, 4.3, and 10.6 kJ mol−1, respectively. The experimental GED data agree well with the presence of only two conformers: χ(ag+g+) = 80(20)% and χ(ag+g-) = 20(10)%.__________Translated from Zhurnal Obshchei Khimii, Vol. 75, No. 5, 2005, pp. 742–750.Original Russian Text Copyright © 2005 by Belyakov, Khramov, Baskakova, Naumov.  相似文献   

13.
From the reactions between M2(TiPB)4 compounds and meta and para-vinylbenzoic acids (2 equiv.) in toluene at room temperature the compounds trans-M2(TiPB)2L2, where L = m-vinylbenzoate 1A (M = Mo) and 1B (M = W) and TiPB = 2,4,6-triisopropylbenzoate, and where L = p-vinylbenzoate 2A (M = Mo) and 2B (M = W) have been isolated. Compounds 1A and 2A have been shown to undergo Heck carbon–carbon coupling reactions with phenyliodide to produce trans-Mo2(TiPB)2(O2CC6H4-m-CHCH–C6H5)2, 3A and trans-Mo2(TiPB)2(O2CC6H4-p-CHCH–C6H5)2, 4A. The molybdenum compounds 1A and 2A have been structurally characterized by single crystal X-ray crystallography. All the new compounds have been characterized by 1H NMR, IR, UV-visible absorption and emission spectroscopy, high resolution MALDI-TOF MS, fs- and ns-transient absorption spectroscopy and fs-time-resolved IR spectroscopy. Electronic structure calculations employing density functional theory, DFT, and time-dependent DFT have been employed to aid in the interpretation of spectral data. All compounds show intense absorptions in the visible region corresponding to M2δ to Lπ* charge transfer transitions. The lifetimes of the 1MLCT state fall in the range of 1–10 ps and for the molybdenum complexes the T1 states are 3δδ* with lifetimes ∼50 μs while for the tungsten complexes the T1 are 3MLCT with lifetimes in the range of 3–10 ns.  相似文献   

14.
Using the ESR method, equilibrium complex formation of fullerene C60 with bis-(5-cyclopentadienyl)vanadium in solutions in aromatic solvents was found to occur. Based on an analysis of isotropic (g i = 2.0008;A i ,(V51)=–45.7 mT) and anisotropic (g i =1.9808;g 2 = 2.0135; <g 3> = 2.0060;A 1(51V)=–7.85 mT;A 2(51V) = –6.50 mT; <A 3(51V)> = 0.61 mT) ESR spectra parameters, it was established that the complex formed, Cp2V(2-C60), corresponds to vanadocene d1-complexes with 2-bonded ligands.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 1945–1947, November, 1994.  相似文献   

15.
A series of complexes of fullerenes C60 and C70 with metal dithiocarbamates {MII(R2dtc)2}·Cm (m = 60 or 70) and metal dithiocarbamates coordinated to nitrogen-containing ligands (L), {MII(R2dtc)2)x·L}·C60 (x = 1 or 2), where M = Cu, Zn, Cd, Hg, Mn, or Fe, R = Me, Et, Prn, Pri, or Bun, L is 1,4-diazabicyclo[2.2.2]octane (DABCO), N,N′-dimethylpiperazine, or hexamethylenetetramine, were synthesized. The shape of dithiocarbamate molecules is sterically compatible with the spherical shape of C60, resulting in an efficient interaction between their π systems. The resulting compounds are characterized by a layered or three-dimensional packing of the fullerene molecules. In the C60 complexes, iron(II) and manganese(II) dithiocarbamates exist in the high-spin states (S = 2 and 5/2). The magnetic susceptibility of {MII(Et2dtc)2}2·Cm (M = Fe or Mn, m = 60 or 70) in the temperature range of 200–300 K is described by the Curie-Weiss law with Θ = −250 and −96 K and with maxima at 110 and 46 K, respectively, which is indicative of a strong antiferromagnetic spin coupling between MII. The Weiss constants for the [{MII(Et2dtc)2}2·DABCO]·C60·(DABCO)2 complexes (M = Fe or Mn) are 1.7 and 0.3 K, respectively. The magnetic moments of the complexes containing Fe and Mn dithiocarbamates slightly increase at temperatures below 50 and 35 K, respectively, which is evidence of the ferromagnetic spin coupling between MII in {MII(Et2dtc)2}2·DABCO. Single crystals of the complexes exhibit low dark conductivity (10−10–10−11 S cm−1). The visible light irradiation of these crystals leads to an increase in the photocurrent by two–three orders of magnitude. The photogeneration of free charge carriers in the complexes occurs both due to the photoexcitation of metal dithiocarbamate (CuII(Et2dtc)2) and through the charge transfer from metal dithiocarbamate (MII(Et2dtc)2, M = Zn or Cd) to C60. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2072–2087, November, 2007.  相似文献   

16.
A series of new [NiX(S2P{O-c-Hex}2)(PPh3)](X = Cl, Br, I and NCS)(1)–(4) and [Ni(NCS)(S2P{OR}2)(PPh3)][R =n-Pr (5), i-Pr (6)] complexes has been synthesized and characterized by elemental analyses, f.i.r., i.r., u.v.–vis., 1H-, 13C{1H}- and 31P{1H}-n.m.r. spectra, magnetochemical and conductivity measurements. A single crystal X-ray analysis of [Ni(NCS)(S2P{O-n-Pr}2)(PPh3)](5) reveals the molecular structure of the complex and confirms a square-planar geometry around the central atom of nickel with the NCS anion coordinated via the nitrogen atom.  相似文献   

17.
The S1←S0 transitions in 3-aminobiphenyl were studied in a supersonic jet by laser-induced fluorescence. The results were compared with ab initio HF, CIS and DFT/SCI calculations and with experimental data for the biphenyl, 1-phenylpyrrole and 2-phenylindole. The equilibrium geometry of the 3-aminobiphenyl in the S1 state is non-planar with the dihedral angle between two phenyl rings about 5.4° (CIS/6-31G*). The torsional potential in the S1 state has been determined by fitting the one-dimensional potential of the form V(φ)= 2 ∑n Vn(1−cos ), to reproduce the observed level spacing (V2=3420, V4=−378, V6=−32.8 and V8=−2.9 cm−1). The observed deuteration effects seem to confirm this potential.  相似文献   

18.
A convenient method is given for the semiquantitative determination of those changes ΔSi in internal coordinates, which describe the structure of the radical cation M+(Ψ) relative to the neutral molecule M in its electronic ground state. The changes ΔSi correspond to those associated with the relaxation process which follows the ionisation M + hvM+(Ψ) + e, M+ being in the electronic state Ψ. The method, based on the procedure originally developped by Smith & Warsop [3], uses the spacing and relative intensity of the vibrational fine-structure components of the bands in the photoelectron spectrum of M. From these data are calculated the changes ΔQk in normal coordinates, which are then transformed into the ΔSi by applying the L -matrix. The changes ΔRCX, ΔRCC and ΔRCH which describe the structure of the radical cations of the four monohaloacetylenes I(X) (X = F, Cl, Br, I) in their 2 II Ω(1) and 2 II Ω(2) states have been determined. It is shown that the results are in agreement with theoretical expectation and that they confirm the band assignement proposed in a previous communication [2].  相似文献   

19.
Ternary Chlorides with Trigonal-Bipyramidal Clusters: [M5(C2)]Cl9 (M = La? Pr) The chlorides [M5(C2)]Cl9 (M = La? Pr) are obtained by metallothermic reduction of the respective trichlorides MCl3 with caesium in the presence of the lanthanide metal and carbon in sealed niobium ampoules at 800°C. They contain trigonal-bipyramidal clusters [M5(C2)] crystallizing with the triclinic crystal system. Only seven of the nine edges of the trigonal bipyramids are brigded by chloride (Cli). Each cluster is surrounded by twelve terminal ligands (Cla) so that units of the composition [M5(C2)Cl7i]Cl12a have to be considered. These are connected not only via Cli–a and Cla–a–a bridges. Rather, Cla–a (one linear and one bent) and Cli–i bridges are also observed.  相似文献   

20.
Compounds of trigonal cluster chloroaqua complexes with cucurbit[8]uril were synthesized by slowly evaporating HCl solutions of chalcogenides heterometallic cubane cluster complexes of molybdenum and tungsten with cucurbit[8]uril in air; the complexes were characterized by X-ray diffraction analysis: (H3O)8[Mo3S4(H2O)2.5Cl6.5]2Cl(PdCl4)·(C48H48N32O16)· 29H2O (a = 13.3183(17) Å, b = 13.7104(18) Å, c = 18.225(3) Å; α = 80.263(3)°, β = 77. 958(3)°, γ = 87.149(4)°, V = 3207.4(7) Å3, space group P , Z = 1, ρ(calc) = 1.900 g/cm3), (H3O)4 [Mo3S4(H2O)3Cl6]2·(C48H48N32O16)3·68H2O (a = 21.413(6) Å, c = 49.832(10) Å; γ = 120°, V = 19788(8) Å3, space group R , Z = 3, ρ(calc) = 1.695 g/cm3), (H3O)6 [Mo3S4(H2O)3Cl6]2Cl2·(C48H48N32O16)·12H2O (a = 15.881(2) Å, b = 17.191(2) Å, c = 23.276(4) Å; β = 98.865(15)°, V = 6278.7(15) Å3, space group P21/c, Z = 2, ρ(calc) = 1.638 g/cm3), [W3S4(H2O)5Cl4]2·(C48H48N32O16)3·35H2O (a = 21.038(3) Å; α = 61.20(1)°, V = 6762.0(14) Å3, space group R , Z = 1, ρ(calc) = 1.582 g/cm3). The [Mo3S4(H2O)3Cl6]2− anion complex was isolated as three geometrical isomers.Original Russian Text Copyright © 2004 by E. V. Chubarova, D. G. Samsonenko, H. G. Platas, F. M. Dolgushin, A. V. Gerasimenko, M. N. Sokolov, Z. A. Starikova, M. Yu. Antipin, and V. P. Fedin__________Translated from Zhurnal Strukturnoi Khimii, Vol. 45, No. 6, pp. 1049–1058, November–December, 2004.  相似文献   

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