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1.
We report the surface-enhanced Raman spectra of ethylene and acetylene adsorbed on colloidal silver particles formed by gas aggregation and isolated at low temperatures in solid adsorbate/argon matrices. The spectra of both molecules exhibit modes which are normally Raman-forbidden. Excitation with several visible laser frequencies indicated that the degree of enhancement increased towards the blue. 相似文献
2.
The adsorption of C 2H 4 on W(100) has been studied by ultraviolet photoelectron spectroscopy with hν = 21.22 eV. The spectrum measured after in initial saturation exposure at 80 K exhibits structure which correlates well with energy levels recently calculated by Demuth and Eastman (DE) for sp 3 rehybridized C 2H 4. Dehydrogenation of the adsorbate, either by subsequent heating to 295 K or direct adsorption at 295 K, yields a spectrum which correlates with DE's calculation for sp 2 rehybridized C 2H 2. These results suggest that C 2H 4 and C 2H 2 may be distorted from their planar and linear structures respectively and that the CC bonds on these molecules are stretched by adsorption on W(100). Qualitative arguments suggest that the bonding site for both melecules is directly over a W atom and that the Dewar—Chatt model for πd bonding in organometallic compounds is applicable. 相似文献
3.
We report a new synthesis and characterization of Ir(C 2H 4) 2(C 5H 7O 2) [(acetylacetonato)-bis(η 2-ethene)iridium(I)], prepared from (NH 4) 3IrCl 6 · H 2O in a yield of about 45%. The compound has been characterized by X-ray diffraction crystallography, infrared, Raman, and NMR spectroscopies and calculations at the level of density functional theory. Ir(C 2H 4) 2(C 5H 7O 2) is isostructural with Rh(C 2H 4) 2(C 5H 7O 2), but there is a substantial difference in the ethylene binding energies, with Ir-ethylene having a stronger interaction than Rh-ethylene; two ethylenes are bound to Ir with a binding energy of 94 kcal/mol and to Rh with a binding energy of 70 kcal/mol. 相似文献
4.
LnCl 3 (Ln=Nd, Gd) reacts with C 5H 9C 5H 4Na (or K 2C 8H 8) in THF (C 5H 9C 5H 4 = cyclopentylcyclopentadienyl) in the ratio of 1 : to give (C 5H 9C 5H 4)LnCl 2(THF) n (orC 8H 8)LnCl 2(THF) n], which further reacts with K 2C 8H 8 (or C 5H 9C 5H 4Na) in THF to form the litle complexes. If Ln=Nd the complex (C 8H 8)Nd(C 5H 9C 5H 4)(THF) 2 (a) was obtained: when Ln=Gd the 1 : 1 complex [(C 8H 8)Gd(C %H 9)(THF)][(C 8H 8)Gd(C 5H 9H 4)(THF) 2] (b) was obtained in crystalline form. The crystal structure analysis shows that in (C8H8)Ln(C5H9C5H4)(THF)2 (Ln=Nd or Gd), the Cyclopentylcyclopentadieny (η5), cyclooctatetraenyl (η8) and two oxygen atoms from THF are coordinated to Nd3+ (or Gd3+) with coordination number 10. The centroid of the cyclopentadienyl ring (Cp′) in C5H9C5H4 group, cyclooctatetraenyl centroid (COTL) and two oxygens (THF) form a twisted tetrahedron around Nd3+ (or Gd3+). In (C8H8)Gd(C5H9C5H4)(THF), the cyclopentyl-cyclopentadienyl (η5), cyclooctatetraenyl (η8) and one oxygen atom are coordinated to Gd3+ with the coordination number of 9 and Cp′, COT and oxygen atom form a triangular plane around Gd3+, which is almost in the plane (dev. -0.0144 Å). 相似文献
5.
Two new salts of malonic acid have been prepared: the copper(II) malonate tetrahydrate and the copper(II)-ammonium double malonate. Their study by thermal analysis (TG and DTA) leads to the following results:Cu(C 3H 2O 4)·4H 2O: the dehydration is rather complex and it is only under careful conditions that an intermediate hydrate Cu(C 3H 2O 4)·3H 2O could be traced. At about 170°C the dehydration is not ended (the salt holds yet about 0.15H 2O) and the anhydrous salt occurs only at about 240°C. It decomposes immediately leading to residues the composition of which depends upon the surrounding atmosphere; the part played by the gas given off is discussed.Cu(NH 4) 2(C 3H 2O 4) 2: this salt melts and decomposes simultaneously at about 190°C. During the decomposition the copper nitride Cu 3N forms as intermediate compound (as well as copper metal). Concerning the final residues of the decomposition the results and the conclusions are the same as the ones of the previous case. 相似文献
6.
The results of several MC SCF calculations on CH 4, C 2H 4 and C 2H 6 with minimun bases of Slater type AO's are reported. The computing method is a quadratically convergent process. Better final energies are obtained if localized MO's are used. 相似文献
7.
The NIR and IR transmission spectra at room temperature of single crystals of (C 2H 5NH 3) 2PdCl 4 (EAPdC) have been measured, as well as unpolarized Raman spectra at room and liquid-nitrogen temperature. These vibration spectra are compared with those of EACuC and EACdC. We conclude that EAPdC belongs to the family of compounds EAMC, where M = Mn, Cu, Cd. 相似文献
8.
Infrared laser-induced fluorescence measurements of vibrational relaxation in cyclopropane are presented. Following laser excitation of the CH-stretch vibrations υ 6 and υ 8 time-dependent fluorescence signals from υ 10 and υ 7/υ 11 were recorded. Activation and deactivation rate constants for C 3H 6C 3H 6 collisions were found for υ 10 and υ 7/υ 11. A simplified model for the vibrational relaxation of cyclopropane is discussed. 相似文献
9.
C 2(a 3π u) disappearance rate constants of 1.44, 0.96, 0.0296, 0.0130 and < 10 ?6(x10 ?10cm 3s ?1) are reported for reactions with C 2H 4, C 2H 2, O 2, C 2H 6, and CH 4, respectively at 298 K. C 2(a 3π u) fragments are generated by multiphoton ArF excimer laser photodissociation at C 2H 2, and monitored by dye laser induced fluorescence. Arguments are presented which favor chemical reactions over the C 2(a 3π u) → (X 1σ +g) quenching channel. C 2 + C 2H 2 represents the one possible exception to the reactive channel. 相似文献
10.
IR and Raman spectra of gaseous and solid CpGeX 3 species (Cp C 5H 5 and X = Cl, Br, I) are reported. The results are compared with those obtained previously for CpTiCl 3. Internal rotation barriers and thermodynamic functions are reported. 相似文献
11.
Ohne Zusammenfassung 相似文献
12.
The conversion of CO 2 into value-added chemicals coupled with the storage of intermittent renewable electricity is attractive. CuO nanosheets with an average size and thickness of ~ 30 and ~ 20 nm have been developed, which are in situ reduced into Cu nanosheets during electrochemical CO 2 reduction reaction(ECO 2RR). The derived Cu nanosheets demonstrate much higher selectivity for C 2H 4 production than commercial CuO derived Cu powder, with a... 相似文献
13.
When the products of the reaction between F atoms produced in a microwave discharge and C 2H 4 are frozen in a large excess of argon at 14 K, new infrared absorptions appear which can be assigned to the 2-fluoroethyl radical. Studies of the dependence of the product distribution on the F-atom concentration have confirmed that the stabilization of C 2H 4F 2 plays only a minor role under the sampling conditions typical of these experiments. Isotopic substitution experiments have demonstrated that the steric configuration about the CH bond is randomized as a result of the F-atom reaction. Upon irradiation of the sample with the full light of a medium-pressure mercury arc, absorptions of vinyl fluoride and acetylene and of the acetylene—HF complex grow in intensity, while those of FCD 2CH 2 and of FCH 2CD 2 diminish in intensity and those of FCH 2CH 2 a nd of FCH 2CD 2 are unchanged. The F-atom reactions and photolysis processes which occur in these experiments are discussed, and a tunnelling mechanism is proposed to explain the isotopic selectivity in the 2-fluoroethyl photodecomposition. The vibrational spectrum of FCH 2CH 2 is compared with that derived in a recent ab initio calculation. 相似文献
14.
High pressure vapour-liquid equilibrium data for the C 2H 6 + N 2, C 2H 4 + N 2, C 3H 8 + N 2, and C 3H 6 + N 2 systems are presented. The data are obtained isothermally in the range from 200 K to 290 K. For each point of data, temperature, pressure and liquid and vapour phase mole fractions are measured.Values for the vapour phase mole fractions are calculated from the obtained pressure, temperature and liquid phase mole fractions. The calculated values are compared with the experimental results, and it is found that the average mean deviation between calculated and experimental mole fractions is less than 0.009 for the systems considered in this work. 相似文献
16.
The complex dicarbonylbis(diphenylethylphosphine)platinum, Pt(CO) 2[P(C 6H 5) 2(C 2H 5)] 2, crystallizes in either of the enantiomorphous space groups P3 121 (No. 152) and P3 221 (No. 154) with cell dimensions a = 10.64(1), c = 22.06(1) Å, U = 2163 Å 3; pc = 1.564 g/cm 3 for Z = 3, pm = 1.55(3) g/cm 3. The intensities of 1177 independent reflections have been determined by counter methods with MoKα monochromatized radiation. The structure has been solved by the heavy atom method. The refinement, carried out by full-matrix least squares down to a final R factor of 0.042, has enabled the absolute configuration of the crystal sample (space group P3 121) to be ascertained. The molecule is roughly tetrahedral, and has the metal atom lying on a two-fold axis of the cell. Bond parameters are: PtC = 1.92(2) Å, PtP = 2.360(4) Å, CPtC = 117(1)° and PPtP = 97.9(2)°. The PtC 2 and PtP 2 moieties make a dihedral angle of 86.0(3)°. The overall C2 symmetry of the molecule is probably only a statistically averaged situation, a disorder in the PtCO interactions being apparent from the orientations of the thermal ellipsoids of the C and O atoms. 相似文献
17.
A new vanadium(III) phosphite, (C 4H 8N 2H 4) 0.5(C 4H 8N 2H 3)[V 4(HPO 3) 7(H 2O) 3]1.5H 2O, has been synthesized hydrothermally by using V 2O 5, H 3PO 3 as reactants, piperazine as the structure-directing agent. The as-synthesized product was characterized by powder X-ray diffraction, IR spectroscopy, inductively coupled plasma analysis, thermogravimetric analysis, and SQUID magnetometer. Single-crystal X-ray diffraction analysis shows that the title compound crystallized in the trigonal space group (No. 165) with the parameters: , , and Z=4. Its structure is built up by alternation of octahedral VO 6 or VO 5(H 2O) and pseudo-pyramidal HPO 3 units to form infinite 2D layers, and these layers are interconnected by sharing vertex-oxygen with octahedral VO 6 units to generate a 3D open-framework structure with 12-membered ring channels in a and b directions, respectively, where there exist entrapped diprotonated and mono-protonated piperazine cations, and water molecules. Magnetic measurement indicates that paramagnetic behavior is observed down to 4 K. 相似文献
18.
The Raman and infrared spectra (4000200 cm ?1) of (C 4H 4P)Mn(CO) 3 and (C 4D 4P)Mn(CO) 3, and of [C 4H 2(CH 3) 2P]Mn(CO) 3 and [C 4D 2(CH 3) 2P]Mn(CO) 3 in the liquid and solid states (10–400 K) have been investigated. A complete vibrational assignment is proposed and valence force fields of the (C 5H 5) and (C 4H 4P) cycles are compared. From these results, it is clearly shown that the (C 4H 4P) rings are more electrophilic and weaker π-electron donors than (C 5H 5) rings, this is in agreement with their chemical behavior. 相似文献
19.
The high-pressure limiting rate constants of the reactions between H or D atoms and three isotopic ethylenes have been measured in the temperature range 206–461 K. Practically no isotope effects due to the differences between the ethylenes could be observed. This result does not agree with the prediction recently made by the activated complex theory. 相似文献
20.
[Cp 4Fe 4(CO) 4] ( 1) reacts with p-BrC 6H 4Li and MeOH in sequence to afford the functionalized cluster [Cp 3Fe 4(CO) 4(C 5H 4- p-C 6H 4Br)] ( 2), while the reaction of 2 with n-BuLi and MeOH produces [Cp 2Fe 4(CO) 4(C 5H 4Bu)(C 5H 4- p-C 6H 4Br)] ( 3). The double cluster [Cp 3Fe 4(CO) 4(C 5H 4)] 2( p-C 6H 4) ( 4) has been prepared by treatment of [Cp 4Fe 4(CO) 4] with p-C 6H 4Li 2 and MeOH in sequence. The electrochemistry of 2 and 4, as well as the crystal structure of 4 have been investigated. 相似文献
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