Extension of the Karplus relationship to vicinal coupling within the P–Ru–S–H moiety of the H2S complexes cis-RuX2(P–N)(PPh3)(SH2) {X = Cl, Br; P–N = [o-(N,N-dimethylamino)phenyl]diphenylphosphine}

1999 ◽  
pp. 2463-2464 ◽  
Author(s):  
Erin S. F. Ma ◽  
Steven J. Rettig ◽  
Brian R. James
Keyword(s):  
Karplus Relationship

Bicyclic dioxaphosphoranes. 2. Spectral properties indicative of a Karplus relationship in phosphoranes

1982 ◽  
Vol 47 (17) ◽  
pp. 3329-3331 ◽  
Author(s):  
Edward L. Clennan ◽  
Choo Heah Poh
Keyword(s):  
Spectral Properties ◽  
Karplus Relationship

Conformation of 5-Amino-5-deoxypentonolactams

1997 ◽  
Vol 62 (12) ◽  
pp. 1919-1930 ◽  
Author(s):  
Karel Kefurt ◽  
Jaroslav Havlíček ◽  
Michaela Hamerníková ◽  
Zdeňka Kefurtová ◽  
Hana Votavová
Keyword(s):  
Carbonyl Group ◽  
Chemical Shifts ◽  
Cd Spectroscopy ◽  
Coupling Constants ◽  
Cd Spectra ◽  
Vicinal Coupling Constants ◽  
Predominant Conformation ◽  
Karplus Relationship

Four configuration isomers of 5-amino-5-deoxy-D-pentonolactam 1a-4a and their tri-O-acetyl derivatives 1b-4b were studied using NMR and CD spectroscopy. For all compounds chemical shifts of the 1H and 13C nuclei as well as of vicinal coupling constants were obtained. Comparison of the observed 3J(H,H) with those calculated for various conformations by a modified Karplus relationship led to the assignment of predominant conformation 3H4(D) or 4H3(D) to the lactams 1a-4a and 1b-4b in solution. The most important factor for determining the conformation seems to be the pseudoequatorial position of the substituent on the carbon next to the carbonyl group. The results of the CD spectra of the lactams 1a-4a in water, interpreted according to the currently used rules, agreed with the NMR results.

scholarly journals A Karplus Equation for the Conformational Analysis of Organic Molecular Crystals

2019 ◽  
Author(s):  
Pierre Thureau ◽  
Isaure Carvin ◽  
Fabio Ziarelli ◽  
Stéphane Viel ◽  
Giulia Mollica
Keyword(s):  
Dft Calculations ◽  
Conformational Analysis ◽  
Organic Compounds ◽  
Liquid State ◽  
Structural Investigation ◽  
Molecular Crystals ◽  
Molecular Fragment ◽  
Dihedral Angles ◽  
Organic Molecular Crystals ◽  
Karplus Relationship

In the liquid state, vicinal J couplings (3J) have been extensively used for conformational analysis of organic compounds, peptides and proteins through the use of empirical Karplus equations. Contrastingly, there are essentially no examples of the use of 3J for quantitative structural investigation of solids. With the support of DFT calculations, we show that 13C-13C 3J couplings measured on a series of 13C-enriched solids can be related to the dihedral angle of the corresponding molecular fragment by a simple Karplus relationship. We show that such function could be successfully used to deduce dihedral angles on a solid compound with known structure.

Complete analysis of the 1H nmr spectrum of tetrahydrothiophene

1980 ◽  
Vol 58 (22) ◽  
pp. 2340-2348 ◽  
Author(s):  
Angel Luis Esteban ◽  
Ernesto Díez
Keyword(s):  
Potential Energy ◽  
1H Nmr ◽  
Time Scale ◽  
Complete Analysis ◽  
Nmr Spectrum ◽  
H Nmr ◽  
Karplus Relationship ◽  
The One

The 1H nmr spectrum of tetrahydrothiophene has been analyzed. The best set of coupling values (Hz) is: [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text] (A and B refer to α-and β-protons and c and t denote respectively the same and opposite sides of the ring). The variances observed between the values of this set and those reported by Lozach etal., particularly the interchange of the [Formula: see text] and [Formula: see text] couplings, are discussed and it is concluded that our set is the one that reproduces the most fine details of the spectrum profile. The proposed set has been selected as being the most physically meaningful, from amongst 24 equally valid sets of couplings, on the basis of a better agreement with the [Formula: see text] and [Formula: see text] values calculated from a Karplus relationship and from the INDO-FPT method respectively. In these calculations it was assumed that the molecule was interconverting rapidly (on the nmr time scale) between two puckered conformations with C2 symmetry. A detailed discussion of the dependence of the couplings on the height of the pseudorotational barrier and on the temperature indicate that the minimum values of the potential energy correspond to these conformations.

Three-Bond C−O−C−C Spin-Coupling Constants in Carbohydrates:  Development of a Karplus Relationship

1998 ◽  
Vol 120 (43) ◽  
pp. 11158-11173 ◽  
Author(s):  
Bidisha Bose ◽  
Shikai Zhao ◽  
Roland Stenutz ◽  
Francis Cloran ◽  
Paul B. Bondo ◽  
...  
Keyword(s):  
Coupling Constants ◽  
Spin Coupling ◽  
Karplus Relationship ◽  
Spin Coupling Constants

The Proton–Proton and Proton–Carbon-13 Spin–Spin Coupling Constants in 1,3-Dioxole and Bis-1,3-dioxolyl. Conformational Dependence

1975 ◽  
Vol 53 (18) ◽  
pp. 2734-2741 ◽  
Author(s):  
Ted Schaefer ◽  
Kalvin Chum ◽  
David McKinnon ◽  
M. S. Chauhan
Keyword(s):  
Double Resonance ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Dihedral Angles ◽  
Proton Proton ◽  
Proton Coupling ◽  
Vicinal Proton ◽  
Karplus Relationship ◽  
Spin Coupling Constants ◽  
Spin Spin Coupling

The carbon-13 satellite peaks in the proton magnetic resonance spectra of 1,3-dioxole and bis-1,3-dioxolyl are analyzed under single and double resonance conditions to yield the signs and magnitudes of proton–proton coupling constants over three, four, and five bonds, and of proton–carbon-13 coupling constants over one, two, and three bonds. The conformational behavior of bis-1,3-dioxolyl contrasts sharply with that of analogous sym-tetrasubstituted ethane derivatives. It is indicated that the two-bond proton–carbon-13 coupling in the ethanic fragment can be used for conformational analysis in a manner similar to vicinal proton–proton couplings. The vicinal three-bond proton–carbon-13 couplings are given for dihedral angles of 180 and 120° and their relative magnitudes are as expected from a Karplus relationship. The two-bond proton–carbon-13 coupling in the olefinic fragment is, at 20.0 Hz, the largest coupling known for such a bond.

THE CONFORMATIONS IN SOLUTION OF trans-CYCLOHEXENE DIHALIDES AND cis- AND trans-1,2-CYCLOHEXANEDIOLS AND DERIVATIVES

1964 ◽  
Vol 42 (4) ◽  
pp. 893-910 ◽  
Author(s):  
R. U. Lemieux ◽  
J. W. Lown
Keyword(s):  
Chemical Shifts ◽  
Coupling Constants ◽  
Spectral Parameters ◽  
Conformational Equilibria ◽  
Karplus Relationship ◽  
In Trans ◽  
Cis And Trans ◽  
Isopropylidene Derivatives ◽  
Derivatives Of

trans-1,4,4-Trideuteriocyclohexene dichloride, dibromide, and diiodide and the 1,4,4-trideuterio-cis- and trans-1,2-cyclohexanediols together with their O-acetyl, O-tosyl, and O-isopropylidene derivatives were synthesized. Their nuclear magnetic resonance (NMR) spectral parameters were obtained with a spectrometer operating at 100 Mc.p.s. and employing double irradiation to establish the chemical shifts and the signs of the coupling constants. The interpretation of the data according to expectations based on the Karplus relationship, for dihedral angles and coupling constants, support the conformational equilibria assigned to the trans-dichloride and trans-dibromide of cyclohexene on the basis of dipole moment measurements (previously published results). The results indicate that trans-cyclohexene diiodide exists to about 84% in the diaxial conformation. In the case of the 1,2-cis-disubstituted cyclohexanes, the occurrence of the signal for the 3-hydrogen in trans relation to the 2-hydrogen at lower field than its geminal 3-hydrogen is assigned to the deshielding influence on the 3-hydrogen when in axial orientation by an opposing axial oxygen at the 1-position. Support for this contention was obtained by determination of the chemical shifts of the geminal hydrogens at the 3- and 5-positions of the cis- and trans-4-t-butyl-2,2,6,6-tetradeuterio-1-methylcyclohexanols. The conformational equilibria indicated for the 1,2-diol, 1,2-diacetoxy, and 1,2-ditosyloxy trans derivatives of 1,4,4-trideuteriocyclohexane by NMR parameters obtained from the spectrum of the O-isopropylidene derivatives of the trans-diol allowed conclusions regarding the non-bonded interaction energies involved. The Karplus relation had to be adjusted to the form, [Formula: see text] and [Formula: see text] to accommodate the results. Solvent effects on conformation are noted. Also, the investigation provided further evidence for the opposite signs of the coupling constants for geminal and vicinal hydrogens. A consideration of the chemical shifts observed for a variety of derivatives of cyclohexanol appears to indicate that intramolecular shielding effects are better accounted for on the basis of neighboring atomic groupings than on the basis of individual chemical bonds.

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