Deuterium isotope effects as evidence for substituent perturbation of the π-electron frame in benzanilides
✍ Scribed by Martha S. Morales-Ríos; Víctor Pérez-Alvarez; Pedro Joseph-Nathan; L. Gerardo Zepeda
- Publisher
- John Wiley and Sons
- Year
- 1994
- Tongue
- English
- Weight
- 378 KB
- Volume
- 32
- Category
- Article
- ISSN
- 0749-1581
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✦ Synopsis
Abstract
Deuterium isotope effects on ^13^C nuclear shielding, __^n^__ΔC(D), transmitted across a D‐labelled nitrogen atom were investigated for a series of para‐substituted benzanilides. The two two‐bond isotope shifts, ^2^ΔC(D) are perturbed essentially in a trough‐bond manner by change of the contribution of mesomeric structures. The magnitudes of ^2^Δ(CO) and ^2^Δ(C‐1′) are found to be mutually interdependent as evidenced by the linear relationships between the average values of ^2^Δ(CO) and ^2^Δ(C‐1′) with ^1^H(NH) chemical shifts and with ^15^N SCS. This behaviour is interpreted as resulting from a cross‐conjugated transmission pathway involving the carbons sharing the D‐labelled nitrogen.