Multiconfigurational self‐consistent field calculations of nuclear magnetic resonance indirect spin–spin coupling constants

1994 ◽  
Vol 101 (8) ◽  
pp. 6822-6828 ◽  
Author(s):  
Andrzej Barszczewicz ◽  
Trygve Helgaker ◽  
Michael/ Jaszuński ◽  
Poul Jo/rgensen ◽  
Kenneth Ruud
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Consistent Field ◽  
Self Consistent ◽  
Self Consistent Field ◽  
Spin Coupling Constants ◽  
Spin Spin Coupling ◽  
Nuclear Magnetic

Anisotropy of indirect spin–spin coupling constants from nuclear magnetic resonance powder patterns of rigid solids. 1J(31P,199Hg) in [HgP(o-tolyl)3(NO3)2]2

1988 ◽  
Vol 66 (8) ◽  
pp. 1821-1823 ◽  
Author(s):  
Glenn H. Penner ◽  
William P. Power ◽  
Roderick E. Wasylishen
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Coupling Constant ◽  
Spin Coupling Constants ◽  
Fermi Contact ◽  
Spin Spin Coupling ◽  
Contact Mechanism ◽  
Nuclear Magnetic

The anisotropy of the indirect 31P,199Hg spin–spin coupling constant, ΔJ, in solid [HgP(o-tolyl)3(NO3)2]2 is obtained from an analysis of the 31P nuclear magnetic resonance powder pattern. The value of ΔJ, 5170 ± 250 Hz, is large and indicates that mechanisms other than the Fermi contact mechanism are important for this spin–spin coupling. The powder spectrum also indicates that the absolute sign of 1J(31P,199Hg) is positive.

Long-range 13C, 13C spin–spin coupling constants in anisole and some derivatives

1988 ◽  
Vol 66 (7) ◽  
pp. 1635-1640 ◽  
Author(s):  
Ted Schaefer ◽  
Glenn H. Penner
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Methoxy Group ◽  
Chemical Shifts ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Coupling Constant ◽  
Spin Coupling Constants ◽  
Spin Spin Coupling ◽  
Nuclear Magnetic

13C nuclear magnetic resonance chemical shifts and nJ(13C,13C) are reported for anisole and 16 of its derivatives, all enriched with 13C in the methoxyl group. 5J(13C,13C) is directly proportional to sin2θ, where θ is the angle by which the methoxy group twists about the C(1)—O bond. In acetone-d6 solution, 5J(C,C) is not observable for a number of 4-substituted anisoles, except for 1,4-dimethoxybenzene. For the latter, 5J(C,C) is compatible with a twofold barrier of 19.3 ± 1.1 kJ/mol hindering rotation about the C(1)—O bond. However, it is unlikely that the barrier is purely twofold in nature. The observed 5J(C,C) is also compatible with 10.5 and 6.0 kJ/mol for the twofold and fourfold components, respectively, implying a dynamical nuclear magnetic resonance barrier of less than 13 kJ/mol. While phase and solvent effects on the internal barrier in anisole are certainly substantial, it appears that a fourfold component must also be present. The apparent twofold barrier in 2,6-difluoroanisole is 5.4 ± 0.9 kJ/mol, based on 5J(C,C) and 6J(H-4,13C). The latter coupling constant is also reported for 1,2,3-trimethoxybenzene and used to deduce its conformation. The θ dependence of 3J(C,C) and 4J(C,C) is briefly discussed for symmetrical anisole derivatives. Differential 13C, 13C isotope shifts are reported for 1,4-dimethoxybenzene.

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