Nuclear magnetic resonance coupling constant

Venanzi T J 1982 Nuclear magnetic resonance coupling constants and electronic structure in molecules J. Chem. Educ. 59 144-8... 

Nuclear magnetic resonance coupling constants provide a similar indirect measure of changes in bonding on adduct formation. 

S. R A. Sauer, On the accuracy of density functional theory to predict shifts in nuclear magnetic resonance shielding constants due to hydrogen bonding, J. Chem. Theory Comput. 4 (2008) 267 A. Mogelhoj, K. Aidas, K. V. Mikkelsen, S. P. A. Sauer, J. Kongsted, Prediction of Spin-Spin Coupling Constants in Solution based on Combined Density Functional Theory/Molecular Mechanics, J. Chem. Phys. 130 (2009) 134508. 

J A measure of the coupling constant in nuclear magnetic resonance. 

Specinfo, from Chemical Concepts, is a factual database information system for spectroscopic data with more than 660000 digital spectra of 150000 associated structures [24], The database covers nuclear magnetic resonance spectra ( H-, C-, N-, O-, F-, P-NMR), infrared spectra (IR), and mass spectra (MS). In addition, experimental conditions (instrument, solvent, temperature), coupling constants, relaxation time, and bibliographic data are included. The data is cross-linked to CAS Registry, Beilstein, and NUMERIGUIDE. 

The section on Spectroscopy has been retained but with some revisions and expansion. The section includes ultraviolet-visible spectroscopy, fluorescence, infrared and Raman spectroscopy, and X-ray spectrometry. Detection limits are listed for the elements when using flame emission, flame atomic absorption, electrothermal atomic absorption, argon induction coupled plasma, and flame atomic fluorescence. Nuclear magnetic resonance embraces tables for the nuclear properties of the elements, proton chemical shifts and coupling constants, and similar material for carbon-13, boron-11, nitrogen-15, fluorine-19, silicon-19, and phosphoms-31. 

Nuclear Magnetic Resonance Spectroscopy. Nmr is a most valuable technique for stmeture determination in thiophene chemistry, especially because spectral interpretation is much easier in the thiophene series compared to benzene derivatives. Chemical shifts in proton nmr are well documented for thiophene (CDCl ), 6 = 7.12, 7.34, 7.34, and 7.12 ppm. Coupling constants occur in well-defined ranges J2-3 = 4.9-5.8 ... 

Quadrupole coupling constants for molecules are usually determined from the hyperfine structure of pure rotational spectra or from electric-beam and magnetic-beam resonance spectroscopies. Nuclear magnetic resonance, electron spin resonance and Mossbauer spectroscopies are also routes to the property. There is a large amount of experimental data for and halogen-substituted molecules. Less data is available for deuterium because the nuclear quadrupole is small. 

Helgaker, T., Watson, M., Handy, N. C., 2000, Analytical Calculation of Nuclear Magnetic Resonance Indirect Spin-Spin Coupling Constants at the Generalized Gradient Aproximation and Hybrid Levels of Density Functional Theory , J. Chem. Phys., 113, 9402. 

Malkina, O. L., Salahub, D. R., Malkin, V. G., 1996, Nuclear Magnetic Resonance Spin-Spin Coupling Constants from Density Functional Theory Problems and Results , J. Chem. Phys., 105, 8793. 

If one wishes to obtain a fluorine NMR spectrum, one must of course first have access to a spectrometer with a probe that will allow observation of fluorine nuclei. Fortunately, most modern high field NMR spectrometers that are available in industrial and academic research laboratories today have this capability. Probably the most common NMR spectrometers in use today for taking routine NMR spectra are 300 MHz instruments, which measure proton spectra at 300 MHz, carbon spectra at 75.5 MHz and fluorine spectra at 282 MHz. Before obtaining and attempting to interpret fluorine NMR spectra, it would be advisable to become familiar with some of the fundamental concepts related to fluorine chemical shifts and spin-spin coupling constants that are presented in this book. There is also a very nice introduction to fluorine NMR by W. S. and M. L. Brey in the Encyclopedia of Nuclear Magnetic Resonance.1... 

V. Wray, Carbon-carbon coupling constants a compilation of data and a practical guide. In Progress in Nuclear Magnetic Resonance Spectroscopy 1979, Vol. 13, 1979, pp. 177-256. 

The bulky, stable silenes of Brook et al. (104,122-124,168) and Wiberg et al. (166,167) have been the only systems capable of being studied by nuclear magnetic resonance (NMR) spectroscopy to date. Table III lists the 13C and 29Si chemical shifts and the relevant coupling constants of these compounds. 

A nucleus under study by nuclear magnetic resonance techniques is affected by other nuclei in the same molecule. This phenomenon is known as spin-spin coupling. The effect arises (in adjacent nuclei) from the two electrons joining the nuclei in a covalent bond. Suppose the energy of states in which the electrons in the bond have opposing spins is lower than the state in which the electron spins are parallel. Then the AE between the two states (in this case a negative number) is called the coupling constant, J, expressed in frequency units, Hz. Internuclear... 

Nuclear magnetic resonance spectra were obtained for S02C1F solutions at -80 °C. b The symbols, FA and FB, denote axial and equatorial fluorine atoms, respectively. c The anion parameters apply to all carbocation salts and to the Br(OTeF5)2+ salt of Sb(OTeF5)6" also see ref 73. d Predicted from pairwise additivity parameters as described in the Chemical Shifts and Coupling Constant Trends section.f See ref 84 and 85.e The l23Te satellites were not observed. 

A systematic development of relativistic molecular Hamiltonians and various non-relativistic approximations are presented. Our starting point is the Dirac one-fermion Hamiltonian in the presence of an external electromagnetic field. The problems associated with generalizing Dirac s one-fermion theory smoothly to more than one fermion are discussed. The description of many-fermion systems within the framework of quantum electrodynamics (QED) will lead to Hamiltonians which do not suffer from the problems associated with the direct extension of Dirac s one-fermion theory to many-fermion system. An exhaustive discussion of the recent QED developments in the relevant area is not presented, except for cursory remarks for completeness. The non-relativistic form (NRF) of the many-electron relativistic Hamiltonian is developed as the working Hamiltonian. It is used to extract operators for the observables, which represent the response of a molecule to an external electromagnetic radiation field. In this study, our focus is mainly on the operators which eventually were used to calculate the nuclear magnetic resonance (NMR) chemical shifts and indirect nuclear spin-spin coupling constants. 

C and H Nuclear Magnetic Resonance Chemical Shifts and Coupling Constants in the Norbomyl Cation, Cyclopentyl Cation, Nortricyclene, and... 

Nuclear Magnetic Resonance Spectroscopy Coupling Constants... 

Nuclear magnetic resonance (NMR) S Chemical shift, coupling constants, and spectroscopy nuclear Overhauser effect allows calculation of contact points, distances, and conformation... 

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