2JCOCSpin−Spin Coupling Constants Across Glycosidic Linkages Exhibit a Valence Bond-Angle Dependence

2000 ◽  
Vol 122 (2) ◽  
pp. 396-397 ◽  
Author(s):  
Francis Cloran ◽  
Ian Carmichael ◽  
Anthony S. Serianni
Keyword(s):  
Bond Angle ◽  
Valence Bond ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Angle Dependence ◽  
Spin Coupling Constants

NMR spin–spin coupling constants: bond angle dependence of the sign and magnitude of the vicinal3JHFcoupling

2016 ◽  
Vol 18 (34) ◽  
pp. 24119-24128 ◽  
Author(s):  
Renan V. Viesser ◽  
Lucas C. Ducati ◽  
Jochen Autschbach ◽  
Cláudio F. Tormena
Keyword(s):  
Angular Dependence ◽  
Bond Angle ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Angle Dependence ◽  
Spin Coupling Constants ◽  
Spin Spin Coupling

Angular dependence of the sign, magnitude, and through space and through bond transmission of the vicinal3JHFFcoupling.

Indirect Nuclear Spin-Spin Coupling Constants 1J(17O,11B). First Observation And Calculation Using Density Functional Theory (Dft)

2006 ◽  
Vol 61 (8) ◽  
pp. 949-955 ◽  
Author(s):  
Bernd Wrackmeyer ◽  
Oleg L. Tok
Keyword(s):  
Density Functional ◽  
Reasonable Agreement ◽  
Bond Angle ◽  
Calculated Data ◽  
Molecular Structures ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Functional Theory ◽  
Spin Coupling Constants ◽  
Spin Spin Coupling

Coupling constants 1J(17O,11B) of borates, borane adducts and boranes with boron-oxygen bonds have been calculated on the basis of optimised molecular structures using the B3LYP/6-311+G(d,p) level of theory. This indicates that such coupling constants can be of either sign and that their magnitudes can be rather small. Since both 11B and 17O are quadrupole nuclei, it is therefore difficult to measure representative data. In the cases of trimethoxyborane and tetraethyldiboroxanes, it proved possible to obtain experimental data 1J(17O,11B) (22 and 18 Hz) by measurement of 17O NMR spectra at high temperature (120 °C and 160 °C) respectively. The magnitude of these coupling constants is in reasonable agreement with calculated data. In the case of the diboroxane, this points towards a bond angle B-O-B more close to 180◦ than to 140°

A Study of the Bonding and Geometry in Phosphacumulene Ylides

1980 ◽  
Vol 35 (3) ◽  
pp. 343-351 ◽  
Author(s):  
Thomas A. Albright ◽  
Peter Hofmann ◽  
Angelo R. Rossi
Keyword(s):  
Ab Initio ◽  
Molecular Orbital ◽  
Nuclear Spin ◽  
Bond Angle ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Dominant Factor ◽  
Molecular Orbital Calculations ◽  
Highest Occupied Molecular Orbital ◽  
Spin Coupling Constants

A series of ab initio molecular orbital calculations have been carried out on phosphacumulene ylides of the type H3P = C = C = X where X = S, O, CNH, and (OH)2. The variation in the P-C-C bond angle was examined and compared to the experimentally determined structures of analogs. The dominant factor in setting the P-C-C angle was found to be the relative π-acceptor capability of the C = X fragment in the plane of the bending motion. Quantitative PMO-arguments were constructed for the X = S, O and (OH)2 cases along this line. It is also shown, that P-C σ* character mixes into the highest occupied molecular orbital. The magnitude of this effect is dictated by the amount of bending and this strongly influences the 1JP-C nuclear spin coupling constants. Finally, the bending in H3P = C = PH3 was also investigated in a similar manner.

Experimental and Theoretical Estimates of Sigma and Pi Electron Contributions to Long-range Spin–Spin Coupling Constants in Coumarin and its Methyl Derivatives

1973 ◽  
Vol 51 (6) ◽  
pp. 953-960 ◽  
Author(s):  
J. B. Rowbotham ◽  
T. Schaefer
Keyword(s):  
Valence Bond ◽  
Electron System ◽  
Proton Spin ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Orbital Theory ◽  
Coupling Path ◽  
Spin Coupling Constants ◽  
Methyl Derivatives ◽  
Spin Spin Coupling

A full analysis of the p.m.r. spectra of coumarin and five of its methyl derivatives allows the assignment of σ and π electron components to the inter-ring proton–proton spin–spin coupling constants. Magnitudes of up to 0.3 Hz are observed over a coupling path of eight bonds. The σ and π components can be combined on the basis of the appropriate valence bond structures to predict closely the observed parameters in naphthalene, suggesting only weak participation of the ether oxygen atom in the π electron system of coumarin. Calculations of the inter-ring coupling constants at the INDO and CNDO/2 levels of molecular orbital theory are helpful in the interpretation of the observed data, the agreement with experiment being quantitative in many instances. Comparison of the observed coupling constants in coumarin and styrene with the INDO results for an assumed planar form of the latter suggests that styrene exists in a nonplanar conformation.

Vibrational and thermal averaging of the indirect nuclear spin-spin coupling constants of CH4, SiH4, GeH4 and SnH4

1997 ◽  
Vol 91 (5) ◽  
pp. 897-907 ◽  
Author(s):  
SHEELA KIRPEKAR ◽  
THOMAS ENEVOLDSEN ◽  
JENS ODDERSHEDE ◽  
WILLIAM RAYNES
Keyword(s):  
Nuclear Spin ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Spin Coupling Constants ◽  
Spin Spin Coupling
Sign in / Sign up

Export Citation Format

Share Document