Unusual behaviour of the spin–spin coupling constant 1JCH upon formation of CH⋯X hydrogen bond

2020 ◽  
Vol 22 (4) ◽  
pp. 1994-2000
Author(s):  
Elena Yu. Tupikina ◽  
Gleb S. Denisov ◽  
Alexander S. Antonov ◽  
Peter M. Tolstoy
Keyword(s):  
Hydrogen Bond ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Coupling Constant ◽  
Spin Coupling Constant ◽  
Interatomic Distances ◽  
Unusual Behaviour ◽  
Spin Spin Coupling

One-bond coupling constants 1JXY are usually used as a measure of the corresponding X⋯Y interatomic distances.

An estimate of the spin–spin coupling constant, 1J(1H,13C), in gaseous benzene

1996 ◽  
Vol 74 (8) ◽  
pp. 1524-1525 ◽  
Author(s):  
Ted Schaefer ◽  
Guy M. Bernard ◽  
Frank E. Hruska
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Dielectric Constant ◽  
Magnetic Resonance ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Coupling Constant ◽  
Spin Coupling Constant ◽  
Spin Coupling Constants ◽  
Spin Spin Coupling ◽  
Gaseous Benzene

An excellent linear correlation (r = 0.9999) exists between the spin–spin coupling constants 1J(1H,13C), in benzene dissolved in four solvents (R. Laatikainen et al. J. Am. Chem. Soc. 117, 11006 (1995)) and Ando's solvation dielectric function, ε/(ε – 1). The solvents are cyclohexane, carbon disulfide, pyridine, and acetone. 1J(1H,13C)for gaseous benzene is predicted to be 156.99(2) Hz at 300 K. Key words: spin–spin coupling constants, 1J(1H,13C) for benzene in the vapor phase; spin–spin coupling constants, solvent dielectric constant dependence of 1J(1H,13C) in benzene; benzene, estimate of 1J(1H,13C) in the vapor; nuclear magnetic resonance, estimate of 1J(1H,13C) in gaseous benzene.

Signs of spin–spin coupling constants between aldehydic and ring protons in 2,6-dinitrobenzaldehyde. Evidence for a hyperconjugative contribution to JpH,CHO

1969 ◽  
Vol 47 (19) ◽  
pp. 3529-3533 ◽  
Author(s):  
C. L. Bell ◽  
S. S. Danyluk ◽  
T. Schaefer
Keyword(s):  
Aldehyde Group ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Para Position ◽  
Steric Interaction ◽  
Coupling Constant ◽  
Spin Coupling Constant ◽  
Spin Coupling Constants ◽  
Spin Spin Coupling

The spin–spin coupling constant between the aldehydic proton and the proton in the para position, JpH,HCO is negative in 2,6-dinitrobenzaldehyde. JpH,CHO is also very likely negative in 2,6-dichlorobenzaldehyde. It is suggested that steric interaction with the ortho substituents forces the aldehyde group out of a coplanar conformation and leads to an interaction of the aldehydic C–H bond with the π system of the ring. Tentative values of θ, a measure of the deviation from coplanarity, are given.

Signs of long-range amino proton – ring proton coupling constants in N-ethyl-4-chloro-2-nitroaniline

1970 ◽  
Vol 48 (8) ◽  
pp. 1343-1345 ◽  
Author(s):  
T. Schaefer ◽  
R. Wasylishen
Keyword(s):  
Long Range ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Coupling Constant ◽  
Spin Coupling Constant ◽  
Proton Resonance ◽  
Ring Proton ◽  
Multiple Resonance ◽  
Proton Coupling ◽  
Spin Spin Coupling

In N-ethyl-4-chloro-2-nitroaniline there exists a measurable indirect spin–spin coupling constant of ±0.39 ± 0.03 Hz between the methylene protons and ring proton 6. The amino proton is coupled to ring protons 5 and 6 and also to the methylene protons. Consequently, although the amino proton resonance is broad due to incompletely relaxed coupling to 14N, normal multiple resonance experiments show that 5JmH,NH = 0.67 ± 0.03 Hz and 4JoH,NH = −0.35 ± 0.03 Hz.

Indirect Spin-Spin Coupling Between 17O and Other Quadrupolar Nuclei in Oxyanions

1976 ◽  
Vol 31 (9) ◽  
pp. 1046-1050 ◽  
Author(s):  
O. Lutz ◽  
W. Nepple ◽  
A. Nolle
Keyword(s):  
Fourier Transform ◽  
Linear Dependence ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Central Nucleus ◽  
Coupling Constant ◽  
Spin Coupling Constant ◽  
Nmr Studies ◽  
Isoelectronic Series ◽  
Spin Spin Coupling

Abstract Fourier transform NMR studies of 17O, 35Cl, 51V, 53Cr, 55Mn and 95Mo are reported for aqueous solutions of the oxyanions ClO4-, VO43-, CrO42-, MnO4-, and MoO42-, partly enriched in 17O. The indirect spin-spin coupling constant between 17O and the quadrupolar central nucleus is determined:A linear dependence of the reduced coupling constants on the atomic number of the central nucleus in the isoelectronic series VO43-, CrO42- and MnO4- was found.

Internal motion in benzylidene diacetate and its 2,6-dibromo derivative by DNMR and the J method

1989 ◽  
Vol 67 (6) ◽  
pp. 1022-1026 ◽  
Author(s):  
Ted Schaefer ◽  
Craig S. Takeguchi
Keyword(s):  
Double Resonance ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Maximum Magnitude ◽  
Coupling Constant ◽  
Spectral Parameters ◽  
Proton Proton ◽  
Ether Solution ◽  
Spin Spin Coupling ◽  
Dibromo Derivative

The 1H nuclear magnetic resonance spectral parameters are reported for benzylidene diacetate in CS2 and acetone-d6 solutions. The long-range spin–spin coupling constant over six formal bonds, 6J, is used to derive apparent twofold barriers to rotation about the exocyclic C(1)—C bond in the two solutions. The conformation of lowest energy has the α. C—H bond in the benzene plane. The barrier is higher in CS2 than in acetone-d6 solution, in contrast to a molecule like benzyl chloride. In the 2,6-dibromo derivative, the free energy of activation for reorientation about the bond in question is 36 kJ/mol at 165 K in dimethyl ether solution. Such a high barrier implies a very small six-bond proton–proton coupling constant for this derivative because 6J is proportional to the expectation value of sin2θ. The angle θ is zero when the α C—H bond lies in the benzene plane. 6J is −0.051 Hz in acetone-d6 solutions; its sign is determined by double resonance experiments. The question of an angle-independent component of 6J, that is, whether 6J is finite at θ = 0°, is addressed. A maximum magnitude of 0.02 Hz may be present at θ = 0° for the 2,6-dibromo derivative, although a zero magnitude is also compatible with the experimental data. In a compound with a higher internal barrier, α,α,2,6-tetrachlorotoluene, the experimental results are best in accord with a negligibly small 6J at θ = 0°. Keywords: 1H NMR of benzylidene diacetate, spin–spin coupling constants for benzylidene diacetate, DNMR, 2,6-dibromobenzylidene diacetate.

Proton spin–spin coupling constants and intramolecular hydrogen bonding in bromine derivatives of 1,3-dihydroxybenzene

1976 ◽  
Vol 54 (14) ◽  
pp. 2228-2230 ◽  
Author(s):  
Ted Schaefer ◽  
J. Brian Rowbotham
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonding ◽  
Proton Spin ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Hydroxyl Groups ◽  
Oh Groups ◽  
Spin Coupling Constants ◽  
Spin Spin Coupling ◽  
Derivatives Of

The conformational preferences in CCl4 solution at 32 °C of the hydroxyl groups in bromine derivatives of 1,3-dihydroxybenzene are deduced from the long-range spin–spin coupling constants between hydroxyl protons and ring protons over five bonds. Two hydroxyl groups hydrogen bond to the same bromine substituent in 2-bromo-1,3-dihydroxybenzene but prefer to hydrogen bond to different bromine substituents when available, as in 2,4-dibromo-1,3-dihydroxybenzene. When the OH groups can each choose between two ortho bromine atoms, as in 2,4,6-tribromoresorcinol, they apparently do so in a very nearly statistical manner except that they avoid hydrogen bonding to the common bromine atom.

Form of the dihedral angle dependence of the spin-spin coupling constant JHNNH

1989 ◽  
Vol 25 (3) ◽  
pp. 338-341
Author(s):  
L. M. Kapkan ◽  
A. Yu. Chervinskii ◽  
T. M. Pekhtereva ◽  
Yu. I. Smirnov ◽  
A. F. Dmitruk
Keyword(s):  
Dihedral Angle ◽  
Spin Coupling ◽  
Coupling Constant ◽  
Spin Coupling Constant ◽  
Angle Dependence ◽  
Spin Spin Coupling

The proximate spin–spin coupling, 5J(F,CH3), as a quantitative conformational indicator in alkylfluorobenzenes and related compounds

1986 ◽  
Vol 64 (8) ◽  
pp. 1602-1606 ◽  
Author(s):  
Ted Schaefer ◽  
Rudy Sebastian ◽  
Glenn H. Penner ◽  
S. R. Salman
Keyword(s):  
Nuclear Spin ◽  
Spin Coupling ◽  
Torsional Angle ◽  
Rotational Behaviour ◽  
Coupling Constant ◽  
Spin Coupling Constant ◽  
Spin Spin Coupling ◽  
Torsional Potentials ◽  
Derivatives Of ◽  
Related Compounds

The through-space or proximate nuclear spin–spin coupling constant, 5J(F,CH3) = 5J, between methyl protons and ring fluorine nuclei in alkylfluorobenzenes is postulated as [Formula: see text] θ being the torsional angle for the [Formula: see text] bond. A and B are obtained from the known internal rotational behaviour in 2,6-difluoroethylbenzene and the corresponding cumene derivative. The parameterization is tested on the observed 5J in derivatives of 2,4,6-tri-tert-butyl- and 2,4,6-tri-isopropyl-fluorobenzene, in 2-chloro-6-fluoroisopropylbenzene, 2,6-difluoro-α-methylstyrene, and N-methyl-8-fluoroquinolinium halides. A prediction is made for 5J in 2,6-difluoro-tert-butylbenzene. It appears that the present parameterization allows the derivation of approximate torsional potentials from proximate couplings, for example in α,α-dimethyl-2,6-difluorobenzyl alcohol.

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