Maximum bond order hybrid orbitals II. Correlativity with C-H and C-C spin-coupling constants

1993 ◽  
Vol 84 (6) ◽  
pp. 521-533 ◽  
Author(s):  
Zhen-Min Hu ◽  
Chang-Guo Zhan
Keyword(s):  
Bond Order ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Maximum Bond Order ◽  
Spin Coupling Constants ◽  
Hybrid Orbitals

15N–13C spin–spin coupling constants in some aniline derivatives

1976 ◽  
Vol 54 (5) ◽  
pp. 833-839 ◽  
Author(s):  
Roderick E. Wasylishen
Keyword(s):  
Fourier Transform ◽  
Nmr Spectroscopy ◽  
Bond Order ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Aniline Derivatives ◽  
Spin Coupling Constants ◽  
Spin Spin Coupling ◽  
Order Comparison ◽  
Mo Theory

Nitrogen–carbon spin–spin coupling constants in aniline-15N and some of its derivatives have been measured using 13C Fourier transform nmr spectroscopy. Observed values of 1J(15N,13C) in these aniline derivatives are dependent on the nature of the substituent as well as the solvent. Observed values of 1J(15N,13C) in the amino fragment of a number of amine derivatives are linearly related to the corresponding 1J(15N,H) values in these compounds. The 1J(15N,13C) values in these compounds also appear to be related to the N(s)—C(s) bond order. Comparison of observed 1J(15N,13C) values in a number of compounds with those calculated using INDO–MO theory indicate that 1J(15N,13C) in aniline and its derivatives is negative, that is, 1K(N,C) is positive. Observed and calculated 15N–13C spin–spin coupling constants over two and three bonds are also presented.

Signs of long-range proton–fluorine spin–spin coupling constants in 2-amino-5-bromobenzotrifluoride

1968 ◽  
Vol 46 (4) ◽  
pp. 652-654 ◽  
Author(s):  
D. J. Blears ◽  
S. S. Danyluk ◽  
T. Schaefer
Keyword(s):  
Long Range ◽  
Bond Order ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Trifluoromethyl Group ◽  
Spin Coupling Constants ◽  
Spin Spin Coupling

The signs of the spin–spin coupling constants between the fluorine nuclei in the trifluoromethyl group and the ring protons in 2-amino-5-bromobenzotrifluoride are reported. [Formula: see text] and [Formula: see text] are negative while [Formula: see text] is positive. These signs are in agreement with fluorine contact shifts in certain Ni(II) chelates and therefore provide evidence for hyperconjugation of the CF3 group with the ring. The magnitude of [Formula: see text] is rather larger than expected on the basis of a relationship between the square of the bond order between the relevant ring carbons and the size of the coupling.

13C, 1H-Spin-Spin Kopplungskonstanten Teil III: Naphthalin / 13C, 1H Spin-Spin Coupling Constants Part III: Naphthalene

1978 ◽  
Vol 33 (3) ◽  
pp. 353-354 ◽  
Author(s):  
Horst Seel ◽  
Rafet Aydin ◽  
Harald Günther
Keyword(s):  
Linear Dependence ◽  
Bond Order ◽  
Nmr Spectra ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Spin Coupling Constants ◽  
Spin Spin Coupling ◽  
C Nmr

Abstract Using a newly developed technique that employs highly deuterated compounds and 2H broadband decoupling the 13C, 1H spin-spin coupling constants for naphthalene have been measured from the 13C NMR spectra of α-and β-H-[D7]naphthalene. A linear dependence of the 3J(13C, 1H) data on the central π-bond order is indicated.

The proximate coupling constant, 5J(H,CH3), and the torsional mobility of the thiomethyl group in some thioanisole derivatives

1991 ◽  
Vol 69 (4) ◽  
pp. 620-624 ◽  
Author(s):  
Ted Schaefer ◽  
Rudy Sebastian ◽  
Salman R. Salman ◽  
James D. Baleja ◽  
Glenn H. Penner ◽  
...  
Keyword(s):  
Bond Order ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Torsional Motion ◽  
Coupling Constant ◽  
Methyl Group ◽  
H Nmr ◽  
Spin Coupling Constants ◽  
Spin Spin Coupling ◽  
Ortho Substituent

The proximate coupling constants, 5J, between ortho and methyl protons in thioanisole and 18 of its derivatives are discussed as conformational indicators. On the assumption that 5J varies as cos4θ, for 0° ≤ θ ≤ 90°, θ being the angle by which the methyl group twists out of the aromatic plane, 5J for θ = 0° follows as −0.43 (2) Hz from the known internal barrier in thioanisole in solution. A measurement of 5J in meta- or para-substituted thioanisole derivatives then yields an approximate value for the twofold barrier to rotation about the Csp2—S bond. For derivatives containing an ortho substituent, 5J yields an estimate of the torsion angle for the thiomethyl moiety. In some instances these angles are compared with those derived from long-range 1H, 13C and 13C, 13C coupling constants. The size of the ortho substituent appears to have only a small effect on the magnitude of 5J. The major determinant of the latter appears to be the manner in which the substituent perturbs the mobile bond order of the Csp2—S bond. Key words: spin–spin coupling constants, thioanisole derivatives; 1H NMR, thioanisole derivatives; conformations, thioanisole derivatives; conformations, torsional motion of SCH3 group.

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
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