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1.
Christopher M. Johnson Mark G. Shilton Arthur T. Howe 《Journal of solid state chemistry》1981,37(1):37-43
We have measured the ionic conductivities of pressed pellets of the layered compounds MUO2PO4 · nH2O, and correlated the results with TGA data. The conductivities (in ohm?1 m?1), at temperatures increasing with decreasing water content over the range 20 to 200°C, were approximately as follows: Li+4H2O, 10?4; Li+, Na+, K+, and NH4+3H2O, 10?4, 10?2, 10?4, and 10?4; H+, Li+, and Na+1.5H2O, 10?2, 10?4, and 10?4; Na+1H2O, 10?5; H+, K+, and NH4+0.5H2O, all 10?5; and H+, Li+, Na+, K+, NH+4, and , 10?5, 10?5, 10?4, 10?5, 10?5, and 10?6. A ring mechanism is proposed to account for the high conductivity found in NaUO2PO4 · 3.1H2O. The accurate TGA data showed that most of the hydrates had water vacancies of the Schottky type, and should be represented as MUO2PO4(A ? x)H2O, where x can be between 0 and 0.3. 相似文献
2.
The reaction of Fe(CO)(CH2 CHCHCH2)2 with (Ph2 PCH2)2 results in formation of a mixture of two isomers of Fe(CO)(CH2 CHCHCH2)-(Ph2 PCH2 CH2 PPh2). NMR studies concerning the structures of these isomers and their dynamic behavior in solution are described. 相似文献
3.
Solid complexes of boron decachloro-o-carborane and boron decachloro-m-carborane (B10Cl10C2H2) with some oxygen and nitrogen bases have been investigated by infrared and Raman spectroscopy. Complexes containing CH · · O hydrogen bonds are characterized by a relative CH stretching frequency shift up to 12% and a halfwidth of the νCH band up to 220 cm?1. CH · · N hydrogen bonds, with trimethylamine for example, are stronger with a relative shift of about 18% and of about 500 cm?1. Triethylamine complexes, however, form a NH+ · · C? proton transfer hydrogen bond while pyridine can give either CH · · N or C? · · +HN hydrogen-bonded adducts depending on the solvent and temperature. The CH · · N?c? · · +HN equilibrium appears to be shifted towards ion-pair formation at considerably smaller enthalpy values compared to the OH · · N?O? · · +HN system. CH and NH stretching frequencies are correlated with the acidity of the donor and the basicity of acceptor molecules. 相似文献
4.
5.
The transition linewidth ΔE in crystal C6H6, C6D6 and sym-C6H3D3 has been measured as a function of temperature T from 4.2 to 135°K, and it extrapolates to a common value of ΔEo = 50 cm? at O°K. In C6H6 ΔE = (50 + 7T) cm?1, indicative of strong exciton—phonon coupling, and there is a line shift of +40 cm?1 per substituent deuteron. Fluorescence excitation spectral data are used to separate the 1B1u(= S2) decay rate kH = 9.4 × 1012 sec?1, derived from ΔE0, into S2S1 internal conversion (rate ≈ 6.6 × 1012 sec?1) and S2Sx (channel 3) internal conversion (rate ≈ 2.8 × 1012 sec?1. A similar value of kH = 9.9 × 1012 sec?1 is obtained from the S2So fluorescence quantum yield of liquid benzene. 相似文献
6.
Alkenes a–d interact at ?80°C in 15 min. with the Vilsmeier reagent (Me2N=CHCl)+PO2Cl2? in presence of 30% H2O2 to yield the corresponding epoxides a–d. The reaction could involve the formation of the highly reactive hydroperoxymethylenedimethylammonium salt (Me2N=CHOOH)+PO2Cl?2. 相似文献
7.
《Analytical letters》2012,45(7):1213-1233
Abstract Anodic waves of methimazole (I) (1-methylimidazole-2-thiol) and carbimazole (II) (1-ethoxycarbonyl-3-methyl-2-thio-4-imidazoline) on mercury electrodes correspond to mercury salt formation. Both compounds form in the thiono form a soluble complex at pH < 6, compound (I) at higher pH-values a slightly soluble salt of the thiol form. Electrode processes involving the thiol form are complicated by adsorption. Oxidation at solid electrodes occurs only at potentials more than 0.5 V more positive. For compound (I) spectrophotometry indicated pKa=12.0 ± 0.2. By d.c. polarography in 0.1 M H2SO4 containing 10% ethanol the determination of both compounds is possible between 4 × 10? and 1 × 10?3 M, by differential pulse polarography between 1 × 10? and 1 × 10?4 M, by differential pulse voltammetry at HMDE between 5 × l0?7 and 6 × 10? M. 相似文献
8.
D. Lalage S. Brown Joseph A. Connor Henry A. Skinner 《Journal of organometallic chemistry》1974,81(3):403-409
From measurements of the heats of iodination of CH3Mn(CO)5 and CH3Re(CO)5 at elevated temperatures using the ‘drop’ microcalorimeter method, values were determined for the standard enthalpies of formation at 25° of the crystalline compounds: ΔHof[CH3Mn(CO)5, c] = ?189.0 ± 2 kcal mol?1 (?790.8 ± 8 kJ mol?1), ΔHof[Ch3Re(CO)5,c] = ?198.0 ± kcal mol?1 (?828.4 ± 8 kJ mo?1). In conjunction with available enthalpies of sublimation, and with literature values for the dissociation energies of MnMn and ReRe bonds in Mn2(CO)10 and Re2(CO)10, values are derived for the dissociation energies: D(CH3Mn(CO)5) = 27.9 ± 2.3 or 30.9 ± 2.3 kcal mol?1 and D(CH3Re(CO)5) = 53.2 ± 2.5 kcal mol?1. In general, irrespective of the value accepted for D(MM) in M2(CO)10, the present results require that, D(CH3Mn) = D(MnMn) + 18.5 kcal mol?1 and D(CH3Re) = D(ReRe) + 30.8 kcal mol?1. 相似文献
9.
A.A. Pasynskii Yu.V. Skripkin I.L. Eremenko V.T. Kalinnikov G.G. Aleksandrov V.G. Andrianov Yu.T. Struchkov 《Journal of organometallic chemistry》1979,165(1):49-56
(C5H5)2NbBH4 reacts with C5H5M(CO)3Me in toluene solution in the presence of Et3N to give binuclear complexes (C5H5)2NbM(CO)3C5H5 where M is Mo or W (IV and V, respectively). The structure of IV has been studied by X-ray diffraction (the crystals are orthorhombic, a 12.748(5), b 16.745(6), c 14.314 ;; Z = 8, space group of Pbca, automatic difractometer Syntex P2I, λ(Mo-Kα, 1382 reflections, R = 0.056, Rw = 0.058). Molecule IV contains a wedge-like sandwich (π-C5H5)2Nb (NbC 2.37–2.48, CC (av) 1.42 ;, angle between ring planes 49°) linked with the (π-C5H5)Mo(CO) fragment by a direct NbMo bond (3.073 ;) and two bridging CO groups, one nonsymmetrically bonded through the carbon atom only (CO 1.17, NbC 2.53, MoC 2.02 ;) and the other σ-bonded to Mo (MoC 1.944 ;) and π-bonded to Nb (CO 1.22, NbC 2.22, NbO 2.26 ;). Three types of carbonyl groups present in IV give rise to strong IR bands at 1870, 1700 and 1560 cm?1 assigned to the terminal, μ-bridging and σ, π-bridging CO groups respectively. Complex IV has a similar structure. The electronic structure of IV and its dissociation across the NbMo bond are discussed. 相似文献
10.
André L. Beauchamp Stephan Latour Marc J. Olivier James D. Wuest 《Journal of organometallic chemistry》1983,254(3):283-291
The title compound, C58H52Sn3, belongs to the triclinic space group P, with a 10.165, b 13.365, c 18.670 Å, α 96.28, β 93.88, γ 103.15°, V = 2443.8 Å3, fw = 1105.1, Z = 2, Dcalc 1.501 g cm?3, m.p. 206.5–208°C, λ(Mo-K) 0.71069 Å. The structure was refined on 2684 nonzero reflections to an R factor of 0.044. The crystal contains molecules in which the (SnCH2)3CH core possesses an approximate C3 symmetry. The three SnC(H2) bonds are gauche to the C(4)-H bond. Repulsive interactions involving the bulky Ph3Sn substituents lead to large SnC(H2)C(H) angles (av. 117.3°), whereas the C(H2)C(H)C(H2) angles at the tertiary carbon average 111.3°. Little distortion of the Ph3Sn groups themselves is present, since the PhSnPh angles (av. 109.8°) are almost equal to the C(H2)SnPh angles (av. 109.9°). The molecule as a whole has no symmetry because the aromatic rings in the three Ph3Sn groups have different orientations. The phenyl groups create a pocket in the middle of the molecule which encloses and shields the tertiary hydrogen atom. The resulting inaccessibility of this hydrogen accounts in part for the low reactivity of the title compound in redox reactions. 相似文献
11.
Nmr and UV studies show that -dimethylamino--bromostyrene, I, undergoes SNl reaction in H2O and HClO4 (kSNl = 6 × 10?1sec.?1 at 25°). The vinyl cation has an extraordinary selectivity for capture by aromatic amines relative to H2O, including I itself to give the dimer II. 相似文献
12.
Study and Application of Polarographic Catalytic Wave of Chlordiazepoxide in the Presence of Persulfate 总被引:2,自引:0,他引:2
IntroductionChlordiazepoxide (7 chloro 2 methylamino 5 phenyl 3H 1,4 benzodiazepine 4 oxide)showingpowerfulan tianxietyeffecthasbeenwidelyusedasapsychotherapeu ticdrug .Consequently ,theneedaroseforsensitiveandrapiddeterminationofchlordiazepoxideinblood ,urinean… 相似文献
13.
Absolute rate constants are reported for reactions of C2O(3Σ?) under pseudo-first-order decay conditions. C2O is generated by laser photodissociation of C3O2 at 266 nm, and detected by dye-laser induced fluorescence on the 3Πi-3Σ? transition. Rate constants of (433 ± 12), (3.30 ± 0.12) and (1.12 ± 0.05) × 10?13 cm3 molecule?1 s?1 are reported for reactions with NO, O2 and isobutene. The NO value is approximate due to an apparent dark reaction between NO and C3O2. Upper limits of 1 × 10?14 cm3 molecule?1 s?1 are reported for reactions with H2, CO2, C3H2 and C2H4. The C2O + C3O2 reaction does not follow pseudo-first-order decay kinetics. Two explanations are proposed to explain this observation. Results are compared with previous relative rate measurements and are discussed in terms of their relevance to combustion chemistry. 相似文献
14.
Reactions of HgCl2 with η5-C5H5Fe(CO)2R (R CH2CHCH2 and CH2C(CH3)CH2) in THF at 25°C rapidly afford adducts of the two reactants. These adducts were converted to the corresponding PF6? salts, [η5-C5H5Fe(CO)2(η2-CH2C(R)CH2HgCl)]+ PF6? (R H and CH3), for characterization. Slower reactions with cleavage of the ironcarbon σ bond and elimination of the R group from η5-C5H5Fe(CO)2R occur for R CH2CHC(CH3)2, CH2CHCHC6H5, and CH2CCC6H5. Both elimination and adduct formation are observed when R CH2CHCHCH3. The kinetics of the cleavage reactions are presented and possible mechanisms for both cleavage and adduct formation are discussed. 相似文献
15.
《Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy》1986,42(4):411-425
The complete assignment of the vibrational spectra of 2,5-dimethyl-2,4-hexadiene, 4-methyl-1,3-pentadiene and (E)-2-methyl-1,3-pentadiene was obtained from a comparative analysis of their i.r. and Raman spectra (solid, liquid and gas) in the range 3200-50 cm−1. It is shown that particular vibrational motions strongly interact to give rise to very characteristic modes depending on the site of methyl substitution. The comparison of our results with those of analogous shorter and larger polyenes and polyenals allows us to discuss the various local coupled motions characteristic of unsubstituted (CHCH CH)CH and methyl substituted (CHC(CH3)CH), ((CH3)2CCH) or (CH3CHCH) fragments in polyenic chains. 相似文献
16.
Phosphorus pentafluoride was reported long ago to give adducts 2 PF5 ·5 NH3 (1) and nNH3·PF5 (n= 1 ? 4) (2). None of the compounds was characterised in detail. Repeating the reaction of PF5 and NH3 we found the adduct H3N·PF5, , in 8% yield besides (H2N) 2PF3 (3) and NH4PF6. However, HF and (F2P=N)3 gave in 41% yield. The 1H, 19F, and 31P n.m.r. spectra of exhibit 14NH, 14NPF(cis), and 14NP coupling. The x-ray structure determination shows almost perfect octahedral geometry at phosphorus with a PN bond length of 1.842 ā. Compound is soluble in water without decomposition. Treatment with NH3 leads to the anion H2NPF5?. Upon heating forms in good yield H2NPF4 and NH4PF6. Without a solvent and NH3 react to give (H2N) 2PF3. A mechanism for the ammonolysis of PF5 is proposed. 相似文献
17.
The determination of trace rhenium (VII) by differential pulse polarography in the system of H2SO4-(NHsOH)2 · H2SO4-TeO2?4 is markedly improved by the addition of Nitron, which is adsorbed on the surface of mercury electrode. The limit of detection is down to 2 × 1010 M. The adsorptive peak potential is ?0.80 V (vs. SCE). In the ranges of 5 × 1010—10?8, 1 × 10?5—10?7 and 1 × 10?7—10?6M, there are good linear relationships between the peak current increment and the concentration, of which the relative standard deviations are 9.5, 6.6, 1.8% respectively with the correlation coefficients of linear regression of 0.995–0.999. The results relating to this polarographic wave show that it is an adsorption-catalytic wave. The mechanism of the electrode reaction is discussed. 相似文献
18.
Oxygen can be determined in a perfluorotributylamine emulsion used as a blood substitute by coulometry and polarography. The oxygen uptake of the emulsion (4.3 × 10?3 mol l?1 or 11 ml-% at 25°C and PO2 = 760 mm Hg) is about three times greater than that of water. The adsorption of surfactant on a dropping mercury electrode changes the electrochemical parameters E, α and k3. The marked difference between the diffusion coefficients of oxygen and hydrogen peroxide (ratio 2.6) seems to be proceed from the ejection of oxygen molecules from the perfluorotributylamine droplets and from the insolubility of hydrogen peroxide molecules in the droplets. The constant rate of oxygen release by these droplets was estimated to be 104 s?1 by a stopped-flow spectrophotometric method. This constant rate seems to be linked with the particle diameter (0.2 μm) and the diffusion coefficient in the perfluorotributylamine droplets (1.6 × 10?6 cm2 s?1). 相似文献
19.
Reactions between Ph3SnCH2SAr and 2-NO2C6H4SC? lead to the formation of 2-(ArSCH2-6-NO2C6H3SSC6H4NO2-2 via the [2,3]sigmatropic rearrangement of the S-arylthio-sulphonium ylides H2(Ar)SC6H4NO22. 相似文献
20.
T.J.W. De Bruijn A.N. Ipekoḡlu W.A. De Jong P.J. Van Den Berg 《Thermochimica Acta》1981,45(3):293-303
The kinetics of the thermal decomposition of aqueous manganese nitrate solutions and anhydrous manganese nitrate in air were established from isothermal experiments. By heating the solution, first most of the water evaporates to a composition of equimolar amounts of water and manganese nitrate; this concentrated solution then decomposes to γ-Mn(NO2, NO2 and water, usually in two steps. The first step can be described best by the model [?ln(1 ? α)] = 8.9 × 1011 exp(?121000/RT)t, whereas the second step is described equally well by several models. The kinetic parameters of these models are quite similar, the average activation energy being 141 kJ mole?1.The decomposition of anhydrous Mn(NO3)2, which proceeds in a single step, can also be described with several similar models. In this case the average activation energy is about 92 kJ mole?1. 相似文献