Deuterium-induced primary and secondary isotope effects on 13C,H coupling constants in halomethanes
✍ Scribed by N. D. Sergeyeva; N. M. Sergeyev; W. T. Raynes
- Publisher
- John Wiley and Sons
- Year
- 1998
- Tongue
- English
- Weight
- 200 KB
- Volume
- 36
- Category
- Article
- ISSN
- 0749-1581
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✦ Synopsis
Primary p*J(13C,H) and secondary s*J(13C,H) isotope e †ects on carbonÈproton coupling constants were measured in studies of proton-and deuteron-coupled 13C NMR spectra of the halomethanes CH n D m X 4~n~m , where X is Cl, Br or I. Both e †ects are always negative. The magnitudes of p*J(13C,H) increase with the number of halogen atoms whereas those of s*J(13C,H) decrease. p*J(13C,H) is almost linearly dependent on the number of halogen atoms whereas for s*J(13C,H) the dependence is non-linear. New results for the isotope e †ect on the 13C,H coupling constant in Ñuoroform are in accord with data for the other members of the haloform series. For CH 3 Br and estimates of the main features of the surfaces for the 13C,H coupling constants were made using known CH 3 I molecular force Ðelds.