✍ Scribed by Claude Fabre; Serge Gambarelli; Daniel Jaouen; André Rassat; Louis-Claude Brunel; Claude Chachaty
No coin nor oath required. For personal study only.
A nitroxide biradical 2,6‐dioxy‐2,6‐diaza‐1,1,3,3,5,5,7,7‐octamethyldicyclopentano[b;e]pyridine (1) and the corresponding monoradical (2‐oxy‐6‐hydroxy) were prepared starting from 2,2,5,5‐tetramethyl‐3‐oxopyrrolidine by successive condensation with formaldehyde (KOH) or DMF (K in THF), NH~4~OAc and oxidation (Na~2~WO~4~‐H~2~O~2~). In ethanol, biradical 1 shows a quintet (|J| ≫ |a~N~| = 14.6 G). In frozen ethanol solution, the experimental spectra (X‐band at 120 K and 240 GHz at 7, 15 and 25 K) can be computer simulated with the following parameters: D = −64 G; E = 1 G; g~xx~ = 2.0093; g~yy~ = 2.0064; g~zz~ = 2.0020; A~xx~ = A~yy~ = 8 G; A~zz~ = 32.2 G. From the temperature dependence of the high‐field spectra, D is found to be negative.
📜 SIMILAR VOLUMES
A new phenoxyl-nitroxide hetero biradical was prepared, and the nitrogen hyperfine splitting and giso-value of the biradical in toluene have been determined from its solution ESR spectrum.
## Abstract The ESR spectra of the bis(2,2,6,6‐tetramethyl‐4‐piperidinol‐1‐oxyl) adipate biradical at several temperatures in ethanol solution were simulated, taking into account all allowed conformers corresponding to the rotational isomerism model. The probabilities of these conformers, not acces