摘要:

AbstractThe13C and1H spectra of a series of aromatic ketones, ethers and keto‐ethers were studied using the lanthanide shift reagent (LSR) Yb(fod)3and the data analyzed using the lanthanide induced shift (LIS) ratio method. Studies were carried out on phenalenone, 6‐methoxyphenalenone, 1‐ and 2‐methoxynaphthalene, 1‐indanone, 5‐ and 6‐methoxy‐1‐indanone and flavone and the data obtained subjected to LSR‐substrate geometry analysis as a means of making13C assignments. The utility and limitations of the LSR method for making13C assignments is discussed and the LIS ratio method for LSR‐substrate geometry analysis i

ISSN:0030-4921    

DOI:10.1002/mrc.1270110102

出版商:John Wiley&Sons Limited    

年代:1978

数据来源: WILEY

摘要:

AbstractThe13C n.m.r. spectra of 2‐arylaminothiazoline, ‐thiazine and ‐thiazepine derivatives, and also those of someN‐substituted isomeric pairs were recorded and assigned. The structure of the individual isomers, which as a result of contradictory spectroscopic data had earlier been ambiguous, was established. In addition, the tautomeric structure of someN‐unsubstituted compounds was d

ISSN:0030-4921    

DOI:10.1002/mrc.1270110103

出版商:John Wiley&Sons Limited    

年代:1978

数据来源: WILEY

摘要:

AbstractCarbon‐13 n.m.r. spectra of 3‐hydroxy‐4‐sulpho‐2‐naphthoic, 3‐hydroxy‐5‐sulpho‐2‐naphthoic, 3‐hydroxy‐7‐sulpho‐2‐naphthoic, 5‐sulphosalicylic, 3‐hydroxy‐5,7‐disulpho‐2‐naphthoic, 1‐hydroxy‐4,7‐disulpho‐2‐naphthoic, and 3,5‐disulphosalicylic acids were recorded with and without proton noise‐decoupling. Analyses of the spectra were carried out for all compounds except 3‐hydroxy‐5‐sulpho‐2‐naphthoic acid which dimerized. The fine splitting caused by long‐rang

ISSN:0030-4921    

DOI:10.1002/mrc.1270110104

出版商:John Wiley&Sons Limited    

年代:1978

数据来源: WILEY

摘要:

AbstractCe travail présente une étude structurale par RMN1H et13C d'azines hétérocycliques, l'influence de l'isomerieZ/Esur les déplacements chimiques13C est examinée. L'étude cinétique de la formation et de l'isomérisationZ/Ede ces composés a été effectuée et les mécanismes de ces réactions

ISSN:0030-4921    

DOI:10.1002/mrc.1270110105

出版商:John Wiley&Sons Limited    

年代:1978

数据来源: WILEY

摘要:

AbstractAll carbon‐13 chemical shifts for 11para‐substitutedN,N‐dimethylbenzamides in 1 mole % chloroform solution are reported, with assignments based upon double resonance experiments, analogy to chemical shifts of benzamide, and self‐consistency between experimental and calculated values using recognized substituent parameters. In contrast to earlier reports, the aryl carbon chemical shift assignments forN,N‐dimethylbenzamide are C‐2, 127.0; C‐3, 128.7; C‐4, 129.4, and forp‐chloro‐N,N‐dimethylbenzamide are C‐1, 134.6; C‐4, 135.5 ppm, relative to internal TMS. Good Hammett correlations (σp) are reported for13C chemical shifts of C‐1 (σ = 11.9 ppm) and even for the carbonyl group (σ = −2.3 ppm) but are markedly improved if correlated with σp+ (σ = 9.5 ppm) and Dewar'sF(σ = −1.9 ppm), respectively. Excellent Swain–LuptonFandRcorrelations were found for some of the13C chemical shifts and yielded values for percent resonance contributions to transmission of substituent effects as follows, C‐1, 75 ± 4%; C‐2, 51 ± 3%; CO, 31±2%. These are compared to similar values calculated from the CO of benzoic acids of 34±10%, and from the nitrogen‐15 chemical shifts of benzamides of 56±2%. Correlations of these13C δ values and15N δ values with rotation barriers (ΔG 298≠) forN,N‐dimethylbenzamides were examined, and it was found that while CO δ values correlated only poorly the C‐1 δ values correlated very well, but the best correlation was for15N δ values of benzamides. It is suggested that ΔG 298≠and δ15N are intrinsically related due to their numerical correlation, and the close similarity in

ISSN:0030-4921    

DOI:10.1002/mrc.1270110106

出版商:John Wiley&Sons Limited    

年代:1978

数据来源: WILEY

摘要:

AbstractAbsolute nitrogen screening constants and chemical shifts of someN‐heterocycles are calculated within the CNDO/S level of approximation to Pople's model. Satisfactory agreement between calculated and observed nitrogen chemical shifts is obtained in most cases. The application of the results to the study of tautomeric equilibria is discussed. ‘Pyridine‐type’ nitrogen chemical shifts are dominated byn→ π* transitions together with significant contributions from π → σ* and σ → π* transitions whereas the latter two are the dominant ones for ‘pyrrole

ISSN:0030-4921    

DOI:10.1002/mrc.1270110107

出版商:John Wiley&Sons Limited    

年代:1978

数据来源: WILEY

摘要:

AbstractA number of substituted butatriene‐bis‐tricarbonyliron complexes have been studied by13C and1H n.m.r. spectroscopy. Long range coupling values,J(CCCH), have confirmed chemical shift results that methyl and phenyl groups assume opposite orientations at the coordinated double bonds with the methyl group preferentiallytransto carbon and the phenyl group preferentiallytransto i

ISSN:0030-4921    

DOI:10.1002/mrc.1270110108

出版商:John Wiley&Sons Limited    

年代:1978

数据来源: WILEY

摘要:

AbstractCarbon‐13 screening constants are calculated within the INDO/S level of approximation to Pople's model. Satisfactory agreement is obtained in most cases between the calculated and observed screening results. An analysis of the contributions of the π → σ*, σ → π* and σ → σ* transitions to the paramagnetic term shows that a linear relationship between13C chemical shifts and the lowest energy transition is not present. The average excitation energies are found to vary appreciably among the mole

ISSN:0030-4921    

DOI:10.1002/mrc.1270110109

出版商:John Wiley&Sons Limited    

年代:1978

数据来源: WILEY

摘要:

AbstractTwo bond spin‐spin coupling constants2J(17O1H) are determined for the oxygen in ether, aldehyde, acid, ester and amide groups by line shape analysis of the corresponding17O NMR spectr

ISSN:0030-4921    

DOI:10.1002/mrc.1270110110

出版商:John Wiley&Sons Limited    

年代:1978

数据来源: WILEY

摘要:

AbstractNitrogen‐15—hydrogen coupling constants between15N‐labeled oximes and α‐C‐protons,3J(15NH), of two series ofE/Zketoximes were studied in CCl4, CDCl3, CF3COOH, and DMSO‐d6.15N‐substituted‐methyl phenyl ketoximes constituted the first series and15N‐substituted‐methyl 2‐quinoxalinyl ketoximes the second series studied. Substituents in the first group were H, Me,t‐Bu, NMe2, OMe, Cl, Br and I; in the second they were H, NEt2, and Cl. |3J(15NH)| values for the isomers wherein the aliphatic substituent wasantito the oximino hydroxy group were always larger then those for thesynrelated isomers, permitting assignment of oxime stereochemistry to even a lone oxime diastereomer. Additionally, geminal nitrogen‐15—hydrogen coupling,2J(15NH) effects wer

ISSN:0030-4921    

DOI:10.1002/mrc.1270110111

出版商:John Wiley&Sons Limited    

年代:1978

数据来源: WILEY