Reliability of coupling constants obtained from tris(dipivaloylmethanato)europium shifted proton magnetic resonance spectra

1972 ◽  
Vol 94 (17) ◽  
pp. 6230-6231 ◽  
Author(s):  
Timothy B. Patrick ◽  
Ping H. Patrick
Keyword(s):  
Magnetic Resonance ◽  
Proton Magnetic Resonance ◽  
Coupling Constants ◽  
Magnetic Resonance Spectra

Protonenresonanz-Spektroskopie ungesättigter Ringsysteme I

1965 ◽  
Vol 20 (10) ◽  
pp. 948-956 ◽  
Author(s):  
Harald Günther
Keyword(s):  
Magnetic Resonance ◽  
Concentration Dependence ◽  
Proton Magnetic Resonance ◽  
Chemical Shifts ◽  
Electron System ◽  
Coupling Constants ◽  
Resonance Signal ◽  
Aromatic Character ◽  
Additional Support ◽  
Magnetic Resonance Spectra

The proton magnetic resonance spectra of 1.6-methano- and 1.6-oxido-cyclodecapentaene are described and analyzed in terms of chemical shifts and coupling constants. The results are discussed in connection with the structure and possible aromatic character of these compounds. Measurements of the concentration dependence of the chloroform resonance signal in solutions of both compounds give additional support for the presence of a delocalized 10 π-electron system.

The analysis of the proton magnetic resonance spectra of heteroaromatic systems. V. Diazanaphthalenes

1965 ◽  
Vol 18 (5) ◽  
pp. 707 ◽  
Author(s):  
PJ Black ◽  
ML Heffernan
Keyword(s):  
Carbon Tetrachloride ◽  
Magnetic Resonance ◽  
Long Range ◽  
Iterative Procedure ◽  
Proton Magnetic Resonance ◽  
Chemical Shifts ◽  
Direct Calculation ◽  
Coupling Constants ◽  
Dilute Solutions ◽  
Magnetic Resonance Spectra

The proton magnetic resonance spectra of the four isomeric diazanaphthalenes, quinoxaline, phthalazine, quinazoline, and cinnoline, all as dilute solutions in carbon tetrachloride and acetone, have been investigated at 100 Mc/s. The chemical shifts and coupling constants have been obtained by direct calculation or, where appropriate, by an iterative procedure. Long-range coupling constants between protons separated by five and six bonds have been observed.

Proton magnetic resonance spectra of indolizine and its methyl derivatives and aza analogues

1964 ◽  
Vol 17 (10) ◽  
pp. 1128 ◽  
Author(s):  
PJ Black ◽  
ML Heffernan ◽  
LM Jackman ◽  
QN Porter ◽  
GR Underwood
Keyword(s):  
Magnetic Resonance ◽  
Long Range ◽  
Iterative Procedure ◽  
Proton Magnetic Resonance ◽  
Chemical Shifts ◽  
Coupling Constants ◽  
Methyl Derivatives ◽  
Magnetic Resonance Spectra

The proton magnetic resonance spectra of indolizine, indolizine-1,3-d2, 1- and 2-methylindolizine, 2,3-, 2,5-, 2,6-, and 2,7-dimethylindolizine and 1-, 2-, and 3-azaindolizine have been determined at 100 and/or 60 Mc/s. Unequivocal assignments have been made to all protons and the coupling constants and chemical shifts for indolizine and its aza analogues have been obtained by an iterative procedure. Long-range coupling constants involving protons separated by five and six bonds have been observed.

THE PROTON MAGNETIC RESONANCE SPECTRA OF CHRYSANTHEMUM ETHYL ESTER AND THE RELATED cis- AND trans-CHRYSANTHEMUMIC ACIDS

1962 ◽  
Vol 40 (5) ◽  
pp. 875-881 ◽  
Author(s):  
H. M. Hutton ◽  
T. Schaefer
Keyword(s):  
Magnetic Resonance ◽  
Ethyl Ester ◽  
Proton Magnetic Resonance ◽  
Acid Ethyl Ester ◽  
Proton Spin ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Cis And Trans Isomers ◽  
Cis And Trans ◽  
Magnetic Resonance Spectra

The high-resolution proton magnetic resonance spectra of a mixture of the cis and trans isomers of chrysanthemum monocarboxylic acid ethyl ester have been studied. The cis-chrysanthemumic and trans-chrysanthemumic acids spectra were obtained to facilitate the interpretation of the complex spectra of the ester. The percentage of the trans isomer in the chrysanthemum ester was measured to be 62.0 ± 1.1%. The cyclopropane proton spin coupling constants were found to be Jcis = 8.7 c.p.s. and Jtrans = 5.4 c.p.s., in reasonable agreement with Karplus' calculations of the dependence of coupling constants on the dihedral angle.

Proton magnetic resonance spectra of vinylmetallic compounds. Part I. Tetravinyl and triphenylvinyl derivatives of Group IVB elements

1968 ◽  
Vol 46 (14) ◽  
pp. 2373-2384 ◽  
Author(s):  
Seán Cawley ◽  
Steven S. Danyluk
Keyword(s):  
Magnetic Resonance ◽  
Proton Magnetic Resonance ◽  
Phenyl Group ◽  
Coupling Constants ◽  
Multiple Quantum ◽  
Low Field ◽  
Diamagnetic Anisotropy ◽  
Vinyl Group ◽  
Derivatives Of ◽  
Magnetic Resonance Spectra

A study has been made of the proton magnetic resonance spectra for all of the Group IVB derivatives of the series MVi4 and [Formula: see text]([Formula: see text] = phenyl group and Vi = vinyl group). The spectra were measured at 60 MHz as accurately as possible and the assignment of transitions was checked with a variety of supplemental aids including double irradiation, multiple quantum transitions, and medium effects Final, accurate spectral parameters were derived using both iterative and exact computational methods for solution of the three-spin problem Excellent agreement was obtained between the sets of parameters determined by the two methodsThe chemical shifts for both series of compounds display a number of characteristic trends of which the most notable is a displacement of the vinyl proton signals to low field with increasing atomic number of the M atom In each series the largest shift change is noted in going from the carbon to the silicon derivative These deshieldings have been attributed to the enhanced possibility of dπ–pπ interaction between the central M atom and the vinyl group in higher members of the series Marked changes are also the internal shifts of the vinyl protons down both series of compounds It is concluded that these changes are principally due to the effects of the M—C bond diamagnetic anisotropy The trends in internal shifts can be satisfactorily reproduced by the dipole approximation using Δχ values of 4, 6, 8, 12, and 18 × 10−6 cm3 mole−1 for the C, Si, Ge, Sn, and Pb–carbon bonds respectivelyThe signals for the vinyl protons of the [Formula: see text] series are all located to low field relative to the MVi4 series This deshielding is satisfactorily accounted for by the effects of the phenyl ring diamagnetic anisotropy in the former seriesA linear correlation is observed between the sums of the coupling constants and the electronegativities, Em, of the central M atom for both series of compounds However, the ΣJ values for the [Formula: see text] series are all slightly lower than the corresponding sums for the MVi4 series, indicating that the electronegativity of the phenyl group is somewhat larger than for the vinyl groupA significant solvent and concentration dependence is only noted for compounds belonging to the [Formula: see text] series For example, the trans proton of [Formula: see text] shifts up-field by 4 Hz while the cis proton is displaced down-field by 4 Hz as the concentration of [Formula: see text] is increased to 50 mole % in carbon tetrachloride These changes have been interpreted on the basis of a solute–solute interaction scheme of the type proposed previously for phenyl proton shifts.

Conformations of some dianhydrohexitols

1969 ◽  
Vol 47 (13) ◽  
pp. 2395-2401 ◽  
Author(s):  
F. J. Hopton ◽  
G. H. S. Thomas
Keyword(s):  
Hydrogen Bonding ◽  
Magnetic Resonance ◽  
Proton Magnetic Resonance ◽  
Intramolecular Hydrogen Bonding ◽  
Coupling Constants ◽  
Ring Conformation ◽  
Intramolecular Hydrogen ◽  
Magnetic Resonance Spectra

Proton magnetic resonance spectra of three known diastereoisomers 1,4:3,6-dianhydro-D-glucitol, 1,4:3,6-dianhydro-D-mannitol, 1,4:3,6-dianhydro-L-iditol, and their diacetyl and dimesyl derivatives have been analyzed. The coupling constants obtained have been utilized to determine the conformation of the five-membered rings. Constancy of the couplings between ring protons throughout the series of compounds indicates the existence of one conformation common to all, and this appears to be a composite of the Cs and C2 forms. It is significant that intramolecular hydrogen bonding, which occurs in two of the three diastereoisomers, has little or no effect on ring conformation.

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