ISSN:
0749-1581
Keywords:
Spin-spin coupling
;
angle variations
;
methane
;
Chemistry
;
Analytical Chemistry and Spectroscopy
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
Correlated ab initio calculations of the dependences of the proton-proton spin-spin coupling constant J(H1, H2) in methane with the variation of the H1—C—H2 interbond angle are reported. The other coupling constants, including J(C, H), were simultaneously calculated. The coupling constants J(H1, H2) and J(C, H1) increase nearly linearly with the opening of the interbond angle whereas J(H2, H3) and J(C, H3) decrease. J(H3, H4) is only very slightly affected. The changes are due almost solely to changes in the Fermi contact term. The angular dependence is slightly larger at the SCF level of calculation than at the correlated level. The change in the geminal coupling constant J(H1, H2) with respect to equilibrium geometry is given to within 0.025 Hz by ΔJ(H1, H2) (Hz) = 41.57 sin α12 - 8.90 sin2 α12, where α12 is the increase in the interbond angle with respect to equilibrium ( - 10° ≤ α12 ≤ 10°).
Additional Material:
1 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/mrc.1260310806
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