摘要:

AbstractCoupling between P and (N)H has been observed in the1H{14N}NMR spectra of a series of phosphorus substituted thioformamides, R12/P(X)C(S)NHR2. For R2= H one of the two couplings constants3J(PCNH) is much larger than the other. The larger constant is assumed to be3J(PCNH) (trans) and the magnitude of3J(PCNH) for several compounds with R2= Me or Ph is used to assign the configuration about the C(S)N b

ISSN:0030-4921    

DOI:10.1002/mrc.1270080102

出版商:John Wiley&Sons Limited    

年代:1976

数据来源: WILEY

摘要:

AbstractCarbon‐13 chemical shifts of all twenty‐two dimethylcyclohexanols, formed by the hydrogenation of isomeric xylenols, have been measured and assigned. Conformational peculiarities of dimethylcyclohexanols are discussed on the basis of their carbon‐13 chemical s

ISSN:0030-4921    

DOI:10.1002/mrc.1270080103

出版商:John Wiley&Sons Limited    

年代:1976

数据来源: WILEY

摘要:

AbstractA computerised library search system for13C NMR data is described. Given the spectral data of an unknown compound, the system will retrieve from the library those reference compounds exhibiting similar spectra. For comparison the spectral data are converted into a binary code, designed to reflect the underlying structure rather than exact values for chemical shifts. Thus, the ability of the system to retrieve compounds similar to the unknown (as opposed to identical) is greatly enhanced. A sophisticated search strategy adapting itself automatically to the problem at hand makes the system highly efficient.

ISSN:0030-4921    

DOI:10.1002/mrc.1270080104

出版商:John Wiley&Sons Limited    

年代:1976

数据来源: WILEY

摘要:

AbstractThe structure of pyrazine partially oriented in a liquid crystal has been determined from its proton magnetic resonance spectrum utilising the13C satellites (at natural abundance). Carbon–carbon, carbon‐hydrogen and hydrogen–hydrogen internuclear distance ratios have been deter

ISSN:0030-4921    

DOI:10.1002/mrc.1270080105

出版商:John Wiley&Sons Limited    

年代:1976

数据来源: WILEY

摘要:

AbstractProton and phosphorus magnetic resonance spectra of substituted methylphosphonic acids have been determined as a function of pH. A method has been developed for measuring the31P shift indirectly by optimal heteronuclear decoupling of the1H spectra of samples and standards. Control experiments have demonstrated the broad applicability of this technique to the characterization of low milligram samples ofN‐phosphonomethylglycine and potential metabolite

ISSN:0030-4921    

DOI:10.1002/mrc.1270080106

出版商:John Wiley&Sons Limited    

年代:1976

数据来源: WILEY

摘要:

Abstract13C NMR spectra of 1‐methyl‐, 1‐phenyl‐ and 1, 6‐dimethyl‐pyridinium‐3‐oxide, 3‐methylphthalazinium 1‐oxide and anhydro‐3‐methanesulphonamido‐1‐methylpyridinium hydroxide, together with the corresponding amines and quaternary salts, were determined with and without proton noise‐decoupling. The assignment of resonances was based on the analysis of the fine splitting pattern caused by long range couplings whenever appropriate. A procedure for the estimation of chemical shifts of the s

ISSN:0030-4921    

DOI:10.1002/mrc.1270080107

出版商:John Wiley&Sons Limited    

年代:1976

数据来源: WILEY

摘要:

AbstractQuantitative analyses have been carried out by13C NMR spectroscopy using Fourier transformation. The Overhauser effect, due to the broad band decoupling of protons, has been suppressed using the two existing methods (gated decoupling and paramagnetic species), and results from each are compared. Both require a calibration curve, and the second method, when applied to aromatic substances, needs the ratio between the sample to be analysed and the paramagnetic species to be less than a certain value. Experiments have been made with pure products and blends of pure products containing both saturated and aromatic carbons. The precision of the results is given.

ISSN:0030-4921    

DOI:10.1002/mrc.1270080108

出版商:John Wiley&Sons Limited    

年代:1976

数据来源: WILEY

摘要:

AbstractThe13C and119Sn NMR spectra of 33 organotin compounds of the type RSnMenCl3 −nand related types are discussed. The substituent effects of the groups SnMe3, SnMe2Cl, SnMeCl2and SnCl3(and of some related groups) on the carbon chemical shifts in the alkyl group R have been determined; the SnMe3group causes a small upfield shift of the carbon attached to it, while the other groups cause downfield shifts. The shifts show a monotonic change on replacing methyl groups in Me3Sn by chlorine atoms. The effects on carbons further removed from the tin atom are discussed. Variation in R causes little change innJ(SnC) or δ(11

ISSN:0030-4921    

DOI:10.1002/mrc.1270080109

出版商:John Wiley&Sons Limited    

年代:1976

数据来源: WILEY

摘要:

AbstractProton and13C NMR data are presented for six different compounds containing the fragment C6H5CCH2SiMe3. In a number of instances it was observed that, in the1H NMR spectrum, the SiMe3groups had a chemical shift significantly upfield from internal tetramethylsilane (δ = −0·14 to −0·36). These unexpected upfield chemical shifts of the SiMe3groups are suggested to result from the predominance, on a time averaged basis, of conformations which place the methyl groups attached to silicon in the face of an aromatic ring. The preference for such conformations is, in turn, the result of rotational preferences exhibited by the ‘flat’ aromatic ring. These results suggest that conformational analysis of systems containing a phenyl ring should take more explicit account of the fact that the preferred orientation of this phenyl ring can have a profound influence on the conformation adopted by the remainder of the molecule. In addition, the preferred conformation of the phenyl ring can have a significant effect upon the observed1H NMR chemical shifts, while the13C chemical shifts are relatively insensitive to conformational factors and can be explained by well‐known substituent effects previously delineated for al

ISSN:0030-4921    

DOI:10.1002/mrc.1270080110

出版商:John Wiley&Sons Limited    

年代:1976

数据来源: WILEY

摘要:

AbstractProton magnetic resonance spectra at 100 MHz are described for some zinc complexes of theE‐ andZ‐isomers of pyridine‐2‐carbaldehyde 2′‐pyridylhydrazone ind6‐dimethylsulphoxide solution. Chemical shift data are discussed qualitatively in relation to factors such as the charge on the metal ion, the anisotropy of ligand nitrogen atoms, electric field effects caused by the dipole moment of nitrogen lone pairs, metal‐nonbonded‐hydrogen interactions, ring current effects and the conformational changes undergone by each isome

ISSN:0030-4921    

DOI:10.1002/mrc.1270080111

出版商:John Wiley&Sons Limited    

年代:1976

数据来源: WILEY