scholarly journals The proton magnetic resonance spectra of diterpene alcohols. Spin-spin coupling through four single bonds

1964 ◽  
Vol 17 (3) ◽  
pp. 395 ◽  
Author(s):  
RM Carman ◽  
N Dennis
Keyword(s):  
Magnetic Resonance ◽  
Proton Magnetic Resonance ◽  
Spin Coupling ◽  
Spin Spin Coupling ◽  
Single Bonds ◽  
Magnetic Resonance Spectra

Proton magnetic resonance spectra of some benzo[b]thiophens. An investigation of substituent effects in a heteroaromatic system

1968 ◽  
Vol 21 (7) ◽  
pp. 1853 ◽  
Author(s):  
B Caddy ◽  
M Martin-Smith ◽  
RK Norris ◽  
ST Reid ◽  
S Sternhell
Keyword(s):  
Magnetic Resonance ◽  
Long Range ◽  
Proton Magnetic Resonance ◽  
Chemical Shifts ◽  
Substituent Effects ◽  
Spin Coupling ◽  
Heteroaromatic System ◽  
Spin Spin Coupling ◽  
Magnetic Resonance Spectra

N.m.r. data for 19 5-substituted and 13 polysubstituted benzo[b]thiophens are tabulated. The influence of the substituents at C5 on the chemical shifts of H4 and H6 is discussed. Long-range interproton spin-spin coupling between H3 and H7, and between H2 and H6, is general in benzo[b]thiophens. The vicinal coupling J6,7 in 5-substituted benzo[b]thiophens varies directly and linearly with the electronegativity of the substituents at C5.

Proton magnetic resonance spectra of 3-fluorotoluene and 2-chloro-5-fluorotoluene. The sign and coupling mechanism of

1978 ◽  
Vol 56 (17) ◽  
pp. 2233-2236 ◽  
Author(s):  
Ted Schaefer ◽  
Werner Danchura ◽  
Walter Niemczura
Keyword(s):  
Magnetic Resonance ◽  
Proton Magnetic Resonance ◽  
Spin Coupling ◽  
Coupling Mechanism ◽  
Coupling Constant ◽  
Electron Component ◽  
Electron Contribution ◽  
Full Analysis ◽  
Spin Spin Coupling ◽  
Magnetic Resonance Spectra

A full analysis of the proton magnetic resonance spectra of 3-fluorotoluene and of 2-chloro-5-fluorotoluene, as 10 mol% solutions in CS2, demonstrates that the long-range spin–spin coupling constant over five bonds between methyl protons and fluorine-19 is negative. The coupling mechanism consists of a large positive σ electron component and a negative π electron component. The negative sign of the π electron contribution arises from a spin density in the 2pz orbital at carbon-3, which is opposite in sign to that of the spin densities at C-2 and C-4. Combined with positive hyperfine interaction constants, QCCH and QCF, the consequence is a negative π electron component.

Nuclear magnetic resonance spectra of some aryl derivatives of mercury

1971 ◽  
Vol 24 (2) ◽  
pp. 317 ◽  
Author(s):  
PJ Banney ◽  
PR Wells
Keyword(s):  
Magnetic Resonance ◽  
Proton Magnetic Resonance ◽  
Proton Spin ◽  
Spin Coupling ◽  
Methyl Groups ◽  
Conformational Effects ◽  
Nuclear Magnetic Resonance Spectra ◽  
Spin Spin Coupling ◽  
Derivatives Of ◽  
Magnetic Resonance Spectra

The proton magnetic resonance spectra of a series of arylmercury chlorides containing methyl groups or a single polar substituent have been determined paying particular attention to mercury-proton spin-spin coupling. This is readily observed for protons or methyl groups ortho or meta to mercury but rarely for the para derivatives. The ortho coupling is relatively insensitive to structure whereas the meta coupling shows considerable variations that appear to be associated with conformational effects.

A proton magnetic resonance determination of the small rotational barriers about the C—Si bond in phenyl derivatives of chloro and methyl silanes

1977 ◽  
Vol 55 (3) ◽  
pp. 557-561 ◽  
Author(s):  
William J. E. Parr ◽  
Ted Schaefer
Keyword(s):  
Magnetic Resonance ◽  
Proton Magnetic Resonance ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Molecular Orbital Calculations ◽  
Spin Coupling Constants ◽  
Spin Spin Coupling ◽  
Derivatives Of ◽  
Low Energy Conformations

The long-range spin–spin coupling constants between protons bonded to silicon and ring protons in C6H5SiH3, C6H5SiH2Cl, C6H5SiH2CH3, C6H5SiHCl2, and C6H5SiH(CH3)2 are determined from the proton magnetic resonance spectra of benzene solutions. A hindered rotor treatment of the barrier to internal rotation about the C—Si bond, in conjunction with the coupling constants over six bonds, allows the deduction of the low-energy conformations for C6H5SiH(CH3)2 and for C6H5SiHCl2, as well as of barriers of 1.0 ± 0.2 kcal/mol. The approach becomes less reliable for C6H5SiH2CH3 and for C6H5SiH2Cl and, particularly for the latter compound, the derived barrier is very likely an upper limit only. Ab initio molecular orbital calculations of the conformational energies are reported for C6H5SiH3, C6H5SiH2Cl, and for C6H5SiHCl2.

The yellow pigments of Beauveria species. Structures of tenellin and bassianin

1977 ◽  
Vol 55 (23) ◽  
pp. 4090-4098 ◽  
Author(s):  
Chi-Kit Wat ◽  
A. Gavin Mcinnes ◽  
Donald G. Smith ◽  
Jeffrey L. C. Wright ◽  
Leo C. Vining
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Spin Coupling ◽  
Spectroscopic Evidence ◽  
Nuclear Magnetic Resonance Spectra ◽  
N Isotopes ◽  
Yellow Pigments ◽  
Spin Spin Coupling ◽  
Derivatives Of ◽  
Magnetic Resonance Spectra

Tenellin and bassianin are deduced from chemical and spectroscopic evidence to be the 3-[(E,E)-4,6-dimethylocta-2,4-dienoyl] and 3-[(E,E,E)-6,8-dimethyldeca-2,4,6-trienoyl] derivatives of 1,4-dihydroxy-5-(p-hydroxyphenyl)-2(1H)-pyridone. Spin–spin coupling information in the 1H and 13C nuclear magnetic resonance spectra after biosynthetic enrichment of tenellin with 13C and 15N isotopes was a valuable aid in elucidating the structure.

ORGANIC AND BIOLOGICAL SPECTROCHEMICAL STUDIES: XXII. THE INFRARED, ULTRAVIOLET, AND NUCLEAR MAGNETIC RESONANCE SPECTRA OF SOME SUBSTITUTED 2-INDANONES AND REFERENCE COMPOUNDS

1966 ◽  
Vol 44 (7) ◽  
pp. 759-769 ◽  
Author(s):  
Emil J. Moriconi ◽  
John P. St. George ◽  
W. F. Forbes
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Infrared Region ◽  
Spin Coupling ◽  
Nuclear Magnetic Resonance Spectra ◽  
Two Peaks ◽  
Spin Spin Coupling ◽  
Infrared Data ◽  
Magnetic Resonance Spectra ◽  
Nuclear Magnetic

Infrared, ultraviolet, and nuclear magnetic resonance spectra of the following compounds are reported: 2-indanone (I), trans- and cis-hexahydro-2-indanone (V and XI), 1-chloro-2-indanone-1,3,3-d3 (III), 1-bromo-2-indanone-1,3,3-d3 (IV), 1-chloro-trans-hexahydro-2-indanone (VII), 1-bromo-trans-hexahydro-2-indanone (VIII), some deuterated forms of these compounds, 2-chlorocyclohexanone-2,6,6-d3, and 2-bromocyclohexanone-2,6,6-d3.2-Indanone and trans-hexahydro-2-indanone each display two peaks in the carbonyl infrared region with intensity ratios of approximately 40:1. The origin of these doublets is discussed.Nuclear magnetic resonance spectra were determined to indicate the presence or absence of ring mobility, and spin–spin coupling data were used to support some of the conclusions deduced from the infrared data for some of the compounds.

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