摘要:

AbstractDEPT‐related sequences are proposed which suppress the generally unnecessary direct proton‐carbon correlations from the long‐range optimized heteronuclear chemical shift correlation spectra. One‐bond modulation of long‐range response intensities is removed through the use of a BIRD pulse train. It is demonstrated that these modified sequences are superior to the original 2D DEPT experiment for the detection of long‐range connectivities of protona

ISSN:0749-1581    

DOI:10.1002/mrc.1260270112

出版商:John Wiley&Sons, Ltd.    

年代:1989

数据来源: WILEY

摘要:

AbstractA series of methylvinylgermanes were prepared and their1H,13C and73Ge NMR spectra were determined. The chemical shifts were compared with those of the corresponding methylvinylsilanes and a very good correlation was found. The origin of the chemical shifts could not be simply attributed to the electron densities as estimated by MNDO calculations.

ISSN:0749-1581    

DOI:10.1002/mrc.1260270113

出版商:John Wiley&Sons, Ltd.    

年代:1989

数据来源: WILEY

摘要:

AbstractThedeuterium/hydrogenNMRisotopeeffects on the13C chemical shift (DHIECS) of the cycloalkano[b]indoles 1,2,3,4‐tetrahydro‐9H‐carbazole, 3‐tert‐butyl‐1,2,3,4‐tetrahydro‐9H‐carbazole and 1,2,3,4‐tetrahydrocyclopent‐[b]indole, wherein the labile NH was partially exchanged to ND, were measured at a concentration of 0.83 M in CDCI3and in DMSO‐d6solutions. The DHIECS values show defined trends that allow definitive13C NMR assignments. The isotope effects over three and four bonds for the sp3hybridized carbons are linearly interdependent, even when one of these isotope e

ISSN:0749-1581    

DOI:10.1002/mrc.1260270114

出版商:John Wiley&Sons, Ltd.    

年代:1989

数据来源: WILEY

摘要:

AbstractHigh‐power decoupling, cross‐polarization and magic‐angle spinning techniques were used to obtain high‐resolution119Sn NMR spectra of six organotin chalcogenides. In addition, the207Pb spectrum of bis(triphenyllead)sulphide was obtained. The data were compared with the results of NMR measurements in solution and are discussed in relation to crystallographic considerations. Satellite resonances allow some metal‐metal coupling constants to be determined. The existence of intramolecular crystallographic inequivalence makes this feasible even for (Ph3Pb)2S. Use of a rotation‐synchronized Carr‐Purcell‐Meiboom‐Gill pulse sequence improves the ability to measure such coupling constants, as is demonstra

ISSN:0749-1581    

DOI:10.1002/mrc.1260270115

出版商:John Wiley&Sons, Ltd.    

年代:1989

数据来源: WILEY

摘要:

Abstract14N NMR data and semiempirical molecular orbital calculations are reported for dibenzo‐[1,3a,4,6a]tetrazapentalene (1). The14N signals were assigned by means of the results of the molecular orbital calculations and measured relative signal widths. A comparison was made with results for some azolopyridines. A linear correlation was obtained between the nitrogen shieldings, expressed with respect to the bridging nitrogen atom, and the corresponding relative charge densities. Thus nitrogen nuclear shielding results provide a good estimation of electron charge distribution in these molecules. Compound 1 provides the first case in which the shielding of a pyridine‐type nitrogen atom is greater than that of the indolizine‐type nit

ISSN:0749-1581    

DOI:10.1002/mrc.1260270116

出版商:John Wiley&Sons, Ltd.    

年代:1989

数据来源: WILEY

摘要:

Abstract13C NMR data are presented for 31 variously substituted derivatives of 9‐acridanone and 15 derivatives of 9‐thioacridanone. Unexpected shifts are explained in terms of hydrrgen bonding or tautomeric equilib

ISSN:0749-1581    

DOI:10.1002/mrc.1260270117

出版商:John Wiley&Sons, Ltd.    

年代:1989

数据来源: WILEY

摘要:

AbstractThe13C NMR spectra of two series of substituted tricarbonyl(cyclohexadiene)iron complexes and of subsitituted tricarbonyl(vinylcyclohexene)iron complexes were recorded; 1‐ and 2‐substituted complexes can be distinguished by chemical shift comparison with parent compo

ISSN:0749-1581    

DOI:10.1002/mrc.1260270118

出版商:John Wiley&Sons, Ltd.    

年代:1989

数据来源: WILEY

摘要:

Abstract1H NMR chemical shifts and coupling constants allow the configurational and conformational analysis of both the (rigid) annulated and the (non‐rigid but conformationally homogeneous) alkyl‐substituted 2,3‐ and 3,4‐tetrahydrothi

ISSN:0749-1581    

DOI:10.1002/mrc.1260270119

出版商:John Wiley&Sons, Ltd.    

年代:1989

数据来源: WILEY

ISSN:0749-1581    

DOI:10.1002/mrc.1260270120

出版商:John Wiley&Sons, Ltd.    

年代:1989

数据来源: WILEY

ISSN:0749-1581    

DOI:10.1002/mrc.1260270101

出版商:John Wiley&Sons, Ltd.    

年代:1989

数据来源: WILEY