Carbon-13 and proton chemical shift assignments and proton-fluorine-19 spin-spin coupling constants in oligosaccharides and fluorinated oligosaccharides by two-dimensional carbon-13-proton chemical shift correlation spectroscopy with proton homonuclear decoupling

The proton and fluorine magnetic resonance spectra of 1,3,5-trifluorobenzene oriented in a nematic liquid crystal have been analyzed. The proton and fluorine chemical shift anisotropies are −2.98 p.p.m. and 104 p.p.m. respectively. The absolute signs of the indirect spin–spin coupling constants are: JHH′, JFF, and JHF (ortho) all positive, and [Formula: see text] (para) negative.

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Two-dimensional POMMIE carbon–proton chemical shift correlated 13C NMR spectrum editing

Canadian Journal of Chemistry ◽

10.1139/v90-177 ◽

1990 ◽

Vol 68 (7) ◽

pp. 1145-1150 ◽

Cited By ~ 1

Author(s):

Bruce Coxon

Keyword(s):

Chemical Shift ◽

Pulse Sequences ◽

Coupling Constants ◽

Data Sets ◽

Proton Chemical Shift ◽

Two Dimensional ◽

Chemical Shift Correlation ◽

Linear Combinations ◽

Nmr Spectrum ◽

C Nmr

Two pulse sequences are described for acquisition of two-dimensional, carbon–proton chemical shift correlated 13C NMR spectra by the "phase oscillations to maximize editing technique". One of these sequences provides two-dimensional, carbon–proton chemical shift correlated spectra in which the 1H–1H coupling constants are present in the 1H chemical shift dimension, whereas the other sequence includes a bilinear rotation decoupling unit that removes the vicinal 1H–1H couplings in this dimension. Extensions of these techniques to generation of two-dimensional, carbon–proton chemical shift correlated CH, CH2, and CH313C NMR subspectra from linear combinations of three two-dimensional data sets are described. Decreased residual signals in the edited 2D subspectra have been achieved by Pascal programs that include six floating point coefficients, and a method for their calibration is discussed. Results are reported for troleandomycin (1). Keywords: 13C nuclear magnetic resonance, carbon–proton chemical shift correlation, DEPT, Pascal programs, POMMIE, two-dimensional NMR spectrum editing, troleandomycin.

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Sign-Determination of Spin-Spin Coupling Constants in tert-Butylphosphaalkyne

Zeitschrift für Naturforschung B ◽

10.1515/znb-1992-0323 ◽

1992 ◽

Vol 47 (3) ◽

pp. 437-438

Author(s):

Bernd Wrackmeyer

Keyword(s):

Coupling Constants ◽

Spin Coupling ◽

Positive Sign ◽

Two Dimensional ◽

Tert Butyl ◽

Spin Coupling Constants ◽

Spin Spin Coupling ◽

Sign Determination

The signs o f the coupling constants 1J(31P≡13C) ( > O ) , J(31P13C) ( > O ) , 3J(31P13C) ( > O ) and 4J(31P1H) ( > O ) in tert-butyl-phosphaalkyne (1) were determined by selective 1H {31P} NMR experiments and two-dimensional (2 D ) 13C/1H heteronuclear shift correlations based on nJ(13C1H ) (n = 1,2,3), confirming the previously assumed positive sign of 1J( 31P≡13C) in phosphaalkynes.

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Determination of Absolute Signs of 119Sn-117Sn Spin-Spin Coupling Constants

Zeitschrift für Naturforschung B ◽

10.1515/znb-1994-1017 ◽

1994 ◽

Vol 49 (10) ◽

pp. 1407-1409 ◽

Cited By ~ 7

Author(s):

Bernd Wrackmeyer ◽

Gerald Kehr

Keyword(s):

Long Range ◽

Coupling Constants ◽

Spin Coupling ◽

Two Dimensional ◽

Spin Coupling Constants ◽

Spin Spin Coupling ◽

First Time

AbstractIf for a given system two-dimensional (2D) 119Sn/1H heteronuclear shift correlations can be established for long range coupling constants nJ(119Sn,1H) (n = 4, 6), absolute signs of coupling constants J(Sn,Sn) are accessible by this technique for the first time. This has been demonstrated for tetrakis(trimethylstannyl)allene (1) with 2J(119Sn,117Sn) (>0) and 4J(Sn. 117Sn) (<0) and for tris(trimethylstannyl)phosphane (2) and bis(trimethvlstannyl)- sulfane (3) with 2J(119Sn,117Sn) (<0).

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