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1.
An analysis of the available electrochemical and electronic-sectroscopic data for quadruply metal–metal bonded complexes reveals that the 1(*) transition energy is an approximately linear function of the difference between the electrode potentials at which they are reduced and oxidized to the bond-order 3. 5 complexes. A theoretical framework for interpreting this correlation is provided by extending to the redox potentials a simple zero-differential-overlap model previously applied to 1(*) transition energies. It is suggested on the basis of this model that the simplicity of the empirical relationship between 1(*) energies and redox potentials is a consequence of the particular one- and two-electron energy terms that characterize these complexes; a linear relationship is not required by theory.  相似文献   

2.
The electronic structure of a ruthenium dimer is calculated by SW-X. The configuration lg2u 4g 4u 42g2, corresponding to a quadruple bond and an equilibrium distance of 1.94 A are found. Ionization potentials and electronic transition energies for bonding molecular orbitals are calculated. Changes in the chemical bonding in the series Mo2-Tc2-Ru2 are examined.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 12, pp. 2667–2669, December, 1989.The authors thank A. N. Ivanova and V. K. Gryaznov for supplying programs for calculating the Hartree-Fock atomic functions.  相似文献   

3.
1,1-Dimethyl- and 1-ethyl-1-methyl-2-tetrahydropyridazinium iodides undergo an aminonitrile rearrangement under the action of alkali with the formation of-dialkylaminobutyronitriles.The aminonitrile rearrangement has been used as a method of showing the structure of the oxidation product of 3-methylhexahydropyridazine which is 6-methyl-2-tetrahydropyridazine.Under the action ot NaOH, 3-methyl-substituted 2-tetrahydropyridazinium salts, for which the aminonitrile rearrangement is excluded split off the substituent from the nitrogen atom and undergo far-reaching decomposition.  相似文献   

4.
F19 NMR chemical shifts F are reported for fluoronitroalkanes, which are found to show a nearly linear relation to the NQR shifts for the chlorine and bromine analogs. The spin-spin coupling constant JF-N also indicates that the Hal-C-N angles vary little in the series HalnC(NO2)4-n. The empirical relation can be used to predict the properties of new halonitromethanes. The observed trends in F and Cl when H is replaced by X (with X=Cl, F, or NO2) for the halonitromethanes indicate the sequence NO2, F, Cl as regards shift F towards weaker fields, but the sequence F, Cl, NO2 as regards shift Cl towards higher NQR frequencies. The deviations from a linear relation for mixed halonitromethanes containing electron-donor groups indicate either that the distortion of the tetrahedral angle varies with the halogen or that conjugation effects for F19 NMR are different from those for Cl35 and Br79 NQR.  相似文献   

5.
The oxygen nonstoichiometry (x) of LaTa2-2xNb2xVO9- (x = 0–0.1) solid solutions was studied using Xray phase analysis, vibrational spectroscopy, and radiospectroscopy. A correlation was found between (x) and the unit cell volume V(x) of the solid solutions. It was shown that the infrared spectra of LaTa2VO9- change in passing from = 0 to 0. The structural position of the oxygen vacancy in LaTa2-2xNb2xVO9- is discussed.  相似文献   

6.
Zusammenfassung Eine unter Anwendung des Amalgamverfahrens durchgeführte Untersuchung des Systems Nickel-Zinn ergab bis 50 At.-% Zinn sehr gute Übereinstimmung mit dem Schmelzdiagramm. In Legierungen mit höherem Zinngehalt wurden jedoch, abweichend von den Ergebnissen bisheriger Untersuchungen, zwei einander strukturell sehr ähnliche Phasen und 1 mit schmalem Homogenbereich aufgefunden. Die -Phase ist identisch mit der bereits in Schmelzlegierungen festgestellten monoklinen Kristallart; ihre Zusammensetzung ist aber gegenüber dem Schmelzdiagramm gegen die Nickelseite hin verschoben.Die zinnreichere 1-Phase ist von der -Phase durch einen heterogenen Bereich von nur 2,5% getrennt. Bei höheren Temperaturen tritt eine Aufweitung des - und eine Verengung des 1-Gebietes ein, wobei der zwischen diesen Phasen liegende heterogene Bereich noch schmaler wird; er umfaßt bei 600° nur mehr 0,5%.Mit 3 Abbildungen.Herrn Prof. Dr.A. Klemenc zum 70. Geburtstag gewidmet.  相似文献   

7.
The diene synthesis with N, N-dialkyldiazenium bromides affords a method for the preparation of 1, 1-dialkyl 4-tetrahydropyridazinium salts.  相似文献   

8.
MO LCAO results are presented for the interatomic contribution to the anisotropy of the diamagnetic susceptibility; values of d=–23.5 · 10–6 and d=–13.8 · 10–6 cm3/mole are obtained for the cyclopropane and epoxide ring systems, respectively. The results are used to interpret PMR spectra in terms of the configuration and conformation of the and forms of caran-4-ol and two stereoisomers of caranone.  相似文献   

9.
Binding constants for -cyclodextrin ( -CD) complexes with 1- alkanols and 1- alkanoate ions were determined by analyzing changes ( ) in chemical shifts of guest 13C NMR signals with -CD concentration. The guests gave well-separated 13C NMR signals. The curve-fitting analyses of for individual carbons upon assumption of a simple 1:1 complexation gave virtually the same binding constants (K1) in the cases of guests with relatively short alkyl chains, such as 1-propanol, 1-butanol, 1- pentanol , 1- butanoate , 1- pentanoate , and 1-hexanoate. However, thus obtained individual K1 values were significantly different from one another, when the guests had relatively long alkyl chains such as 1- hexanol , 1- heptanol , and 1-octanoate. In these guests, satisfactorily consistent K1 values were obtained by the curve-fitting analyses of for individual carbons upon an assumption that not only 1:1 but also 2:1 (host:guest) complexation occurs.  相似文献   

10.
    
Summary By means of the amino-acid analyzer (Beckman Instruments) the possibility is examined to determine -aminolaevulinic and -aminovalerianic acids. Both amino-acids are employed to identify unknown peaks in chromatographic analysis of potato sprout extracts. -Aminolaevulinic acid is analyzed with the 150 cm-column. The running-time is about 28 hours in this case. -Aminovalerianic acid must be analyzed with the 50 cm-column. Both amino-acids could be found in potato sprout extracts, the -aminovalerianic acid in traces only.

Der Deutschen Forschungsgemeinschaft sagen wir an dieser Stelle für die Bereitstellung von Sachmitteln unseren verbindlichsten Dank.  相似文献   

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