1H NMR utilization of through-space effects in configurational assignments. I—application to nitriles; determination of the separate effects of the electric field and anisotropy of the CN group
✍ Scribed by Michel Rouillard; Serge Geribaldi; Jean Khazarian; Marcel Azzaro
- Publisher
- John Wiley and Sons
- Year
- 1980
- Tongue
- English
- Weight
- 412 KB
- Volume
- 13
- Category
- Article
- ISSN
- 0749-1581
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✦ Synopsis
Abstract
The changes in chemical shift induced by isomerization for all the ring protons of the Z‐ and E‐5,5‐dimethyl‐2‐cyclohexenylidene acetonitriles depend only on the through‐space effects of the cyano group. The configurational assignments were made taking into consideration the anisotropic and electric field effects, either separately or together. In the first case, the total effects are Δ~XCN~^T^=−14.7×10^−6^cm^3^ mol^−1^ and bμ~CN~^T^=14.7×10^−30^ cm^3^, respectively. The second approach allows the estimation of the values Δ~XCN~=−4.9 × 10^−6^ cm^3^ mol^−1^ and bμ~CN~=9.8 × 10^−3^ cm^3^, reflecting the combined contributions of magnetic anisotropy and electric field to the total effect.