Molecular orbital theory of E2 reactions and nuclear magnetic resonance spin-spin coupling in ethane-like molecules

1972 ◽  
Vol 94 (11) ◽  
pp. 3718-3727 ◽  
Author(s):  
John P. Lowe
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Molecular Orbital ◽  
Spin Coupling ◽  
Molecular Orbital Theory ◽  
Orbital Theory ◽  
Resonance Spin ◽  
Spin Spin Coupling ◽  
Nuclear Magnetic

1H nuclear magnetic resonance and molecular orbital studies of the structure and internal rotations in ethylbenzene

1987 ◽  
Vol 65 (4) ◽  
pp. 873-877 ◽  
Author(s):  
Ted Schaefer ◽  
Glenn H. Penner ◽  
Rudy Sebastian
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Molecular Orbital ◽  
Proton Spin ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Orbital Theory ◽  
Spectral Parameters ◽  
Internal Barrier ◽  
Nuclear Magnetic

Rather extensive geometry-optimized computations at the STO-3G, 4-21G, 4-31G, and 6-31G levels of abinitio molecular orbital theory suggest that the fourfold component of the barrier to internal rotation about the Csp2—Csp3 bond in ethylbenzene amounts to about 20% of the twofold component. The 1H nuclear magnetic resonance spectral parameters, extracted by complete analyses of the spectra arising from the ten protons, are reported for ethylbenzene in acetone-d6, CCl4, CS2, and perfluoromethylcyclohexane solutions. The long-range proton–proton spin–spin coupling constants demonstrate that the internal barrier is insensitive to the polarity of the solvent, in contrast to polar solute molecules such as benzyl fluoride. The coupling constants do not support a dependence of the internal barrier on the internal pressure of the solvent.

Tautomerism and Site of Protonation of 1-Methylcytosine: Proof by Nuclear Magnetic Resonance Spin-Spin Coupling

Science ◽  
1963 ◽  
Vol 142 (3599) ◽  
pp. 1569-1571 ◽  
Author(s):  
H. T. Miles ◽  
R. B. Bradley ◽  
E. D. Becker
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Spin Coupling ◽  
Resonance Spin ◽  
Spin Spin Coupling ◽  
Nuclear Magnetic

The influence of relativistic effects on nuclear magnetic resonance spin-spin coupling constant polarizabilities of H2O2, H2S2, H2Se2, and H2Te2

2018 ◽  
Vol 39 (31) ◽  
pp. 2589-2600 ◽  
Author(s):  
Gabriel I. Pagola ◽  
Martin A. B. Larsen ◽  
Marta Ferraro ◽  
Stephan P. A. Sauer
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Relativistic Effects ◽  
Spin Coupling ◽  
Coupling Constant ◽  
Spin Coupling Constant ◽  
Resonance Spin ◽  
Spin Spin Coupling ◽  
Nuclear Magnetic

1H, 19F, and 13C nuclear magnetic resonance approaches to the barrier to rotation about the Csp2—Csp3 bond in 1,1,1 -trifluoro-2-phenylethane. Proximate coupling constants and molecular orbital computations

1995 ◽  
Vol 73 (9) ◽  
pp. 1387-1394 ◽  
Author(s):  
Ted Schaefer ◽  
Paul Hazendonk ◽  
David M. McKinnon
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Molecular Orbital ◽  
Long Range ◽  
Coupling Constants ◽  
Spin Coupling ◽  
13C Nuclear Magnetic Resonance ◽  
Spin Coupling Constants ◽  
Spin Spin Coupling ◽  
Nuclear Magnetic

The 1H, 19Fand 13C{1H} nuclear magnetic resonance spectra of 1,1,1-trifluoro-2-phenylethane, 1, in CS2–C6D12, acetone-d6, and benzene-d6 solutions, on analysis, yield long-range coupling constants from which are derived the apparent twofold barriers to rotation about the Csp2—Csp3 bonds. The twofold barrier is 9.0(2) kJ/mol, independent of solvent, 4.0 kJ/mol larger than that of ethylbenzene, also independent of solvent. The theoretical barrier heights for the free molecules at the post-Hartree–Fock level of molecular orbital theory (frozen-core MP2/6-31G*) also differ by 4 kJ/mol, but are about 1 kJ/mol higher than the experimental estimates. The perpendicular conformer is the most stable for both molecules. Comparisons are made with the benzyl halides, in which the internal barriers are remarkably sensitive to solvent. A spin–spin coupling constant over five formal bonds, 5J(H, F), involving the ortho protons in 1, is +0.74(2) Hz and is discussed in some detail in terms of its dependence on intenuclear distances (possible through-space interactions). The solvent perturbations of 3J(H, F) and of 2J(C, F) are of opposite sign. Other long-range coupling constants or their absence are also pointed out. For example, those between 19F and 13C nuclei or protons at the meta position are effectively zero; at the para position they are significant. Keywords: 1,1,1-trifluoro-2-phenylethane; 1H, 19F, and 13C NMR; long-range spin-spin coupling constants; through-space 1H, 19F spin–spin coupling constants; internal rotational potential; molecular orbital computations of internal potential.

Chirality-sensitive nuclear magnetic resonance effects induced by indirect spin-spin coupling

2016 ◽  
Vol 145 (20) ◽  
pp. 204201 ◽  
Author(s):  
P. Garbacz ◽  
A. D. Buckingham
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Spin Coupling ◽  
Resonance Effects ◽  
Spin Spin Coupling ◽  
Nuclear Magnetic
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