摘要:

AbstractA new method for the interpretation of NQR spectra is described. The indentification of multiple lines belonging to different transitions\documentclass{article}\pagestyle{empty}\begin{document}$ \frac{1}{2} \to \frac{3}{2}{\rm and}\frac{3}{2} \to \frac{5}{2} $\end{document}is carried out by using the ‘seizure’ of the corresponding low or high frequency transitions in a two‐frequency pulse exper

ISSN:0030-4921    

DOI:10.1002/mrc.1270030502

出版商:John Wiley&Sons Limited    

年代:1971

数据来源: WILEY

摘要:

AbstractElectron spin resonance in some charge‐transfer complexes of 7,7,8,8‐tetracyanoquinodimethane (TCNQ) with sulphanilamides and antibiotics has been investigated.The ESR spectra are caused by two types of paramagnetic centres: the impurity type and the thermally excited type (Wannier spin excito

ISSN:0030-4921    

DOI:10.1002/mrc.1270030503

出版商:John Wiley&Sons Limited    

年代:1971

数据来源: WILEY

摘要:

AbstractThe temperature dependence of NQR frequencies and spin‐lattice relaxation times in Menshutkin's complexes, prepared on the basis of AsCl3and AsBr3have been investigated.The rotational oscillation frequencies νtand the average life times τaof rotational oscillation quanta have been calculated by both the Bayer and Woessner‐Gutowsky the

ISSN:0030-4921    

DOI:10.1002/mrc.1270030504

出版商:John Wiley&Sons Limited    

年代:1971

数据来源: WILEY

摘要:

AbstractPMR spectra of thirty‐eight chloromethylthiophene and seven dithienylmethane derivatives were observed at 60 or 40 MHz. The chemical shifts of methylene protons were 4·63 to 5·25 ppm for monosubstituted 2‐chloromethylthiophenes and 4·37 to 4·56 ppm for monosubstituted 3‐chloromethylthiophenes, respectively, with reference to TMS. Those for 2,2′ ‐dithienylmethanes, which have one substituent in each ring, were 4·12 to 4·34 ppm. These shifs are useful for determination of the positions of the methylene groups in the related compounds. The long‐range coupling constants observed for methylene proton signals are also useful for the determination of the position

ISSN:0030-4921    

DOI:10.1002/mrc.1270030505

出版商:John Wiley&Sons Limited    

年代:1971

数据来源: WILEY

摘要:

AbstractLe spectre RMN de l'acétone orientée dans lep‐(p′ ethoxyphenyloxycarbonyl)phényl carbonate de butyle est étudié dans l' intervalle de température 48° à 58°C. La mesure des constantes de couplage direct permet de calculer les facteurs d' orientation moléculaires; ceux‐ci permettent de mettre en évidence ici l' intervention de la polarisabilité dans le phénom

ISSN:0030-4921    

DOI:10.1002/mrc.1270030506

出版商:John Wiley&Sons Limited    

年代:1971

数据来源: WILEY

摘要:

AbstractThe proton magnetic resonance spectra of the three title carbanions have been observed in THF with potassium as a counter ion. Theortho‐protons in the α‐methylbenzyl carbanion are nonequivalent at room temperature. This shows that the α‐carbon in this carbanion is in the near‐sp2configuration. The aromatic proton chemical shifts of the benzylpotassium obtained here are at higher shielding than those of benzyllithium reported previously by Sandel and Freedman. This seems to arise from the different ionic nature of the bonds between carbon and metal in the c

ISSN:0030-4921    

DOI:10.1002/mrc.1270030507

出版商:John Wiley&Sons Limited    

年代:1971

数据来源: WILEY

摘要:

AbstractBei NMR‐Untersuchungen dercis‐ undtrans‐Reihe Prolin‐enthaltender Diketopiperazine konnten Unterschiede zwischen den Signalen pseudoaxialer und pseudoäquatorialer Substituenten (α‐Proton, α‐Methylgruppe, α‐iso‐Propylgruppe)

ISSN:0030-4921    

DOI:10.1002/mrc.1270030508

出版商:John Wiley&Sons Limited    

年代:1971

数据来源: WILEY

摘要:

AbstractThe rotational barriers about the CN bond of eightm‐ andp‐substitutedN,N‐dimethyl cinnamamides have been determined by the iterative total line shape NMR method. The ΔG 298·2 −≠values have been correlated with the substituent constants σ, σnand σ+. By comparison of the results with literature data, some conclusions about the accuracy of the barrier determination as well as the transmittance of polar effects in conjugated am

ISSN:0030-4921    

DOI:10.1002/mrc.1270030509

出版商:John Wiley&Sons Limited    

年代:1971

数据来源: WILEY

摘要:

AbstractA simple procedure is provided for the quantitative analysis of Diels‐Alder adduct prepared from commercial methylcyclopentadiene and maleic anhydride by NMR spectra without further separation of its components. The adduct is considered as a mixture ofendonorbornene derivatives (Cn), (Dn), (E) and (Fn) which are obtained from 1‐, 2‐ and 5‐methylcyclopentadiene and cyclopentadiene, respectively.The quantitative analysis of the adduct can be made on a basis of the ratio of the signal intensities of the olefinic protons in the adduct. The result shows that the adduct prepared under mild conditions mainly consists of three norbornene derivatives (Cn), (Dn) and (Fn), with a negligibly small amount of (E). When the adduct prepared under mild conditions is heated, it contains theexoisomers (Cx), (Dx) and (Fx). The ratio of theendoand theexonorbornene derivatives, i.e. ((Cn) + (Dn) + (Fn)):((Cx) + (Dx) + (Fx)), may be estimated from the signal intensities of the 5‐ and 6‐protons.As the result of the analyses of the adducts which are obtained by heating at different temperatures the adduct prepared under mild conditions, the mole fraction of 2‐methyl isomers (Dn) and (Dx), which is found to be 58 % in the adduct prepared at − 15°C, keeps on increasing with rising temperature and shows almost the same value, ∼86%, when heated above 150°C. Therefore, the equilibrium between 1‐methyl and 2‐methyl isomers does not change above 150°C. On the other hand, the isomerization fromendotoexoisomers is not found below 110°C, and thenexoisomers keep

ISSN:0030-4921    

DOI:10.1002/mrc.1270030510

出版商:John Wiley&Sons Limited    

年代:1971

数据来源: WILEY

摘要:

Abstract13C shielding constants have been calculated for a series of alkanes, methane to pentane. The quantities σdand σphave been obtained, using an average excitation energy approximation and the extended Hückel MO wave functions in terms of the Pople method. The results fit the experimental data and the VB results of Grantet al. fairly well. The quantity σdvaries within a wide range for carbon atoms of various degrees of substitution. Two conformations of the hydrocarbons studied have been calculated. The results show that the13C chemical shifts may be used for conformational analy

ISSN:0030-4921    

DOI:10.1002/mrc.1270030511

出版商:John Wiley&Sons Limited    

年代:1971

数据来源: WILEY