Atropisomers of three Blatter radicals were obtained by the addition of 8-substituted 1-naphthyllithiums to 3-phenyl and 3-t-butylbenzo[e][1,2,4]triazine and separated by chiral high-performance liquid chromatography. Their absolute configurations were assigned by a comparison of experimental and time-dependent density functional theory calculated electronic circular dichroism spectra. The free energy of activation, ΔG^‡₂₉₈, and the half life of racemization, t_1/2, at 298 K were determined at ∼25 kcal mol^–1 and <130 h, respectively. Intramolecular π–π interactions in radicals were evident from single-crystal X-ray diffraction, density functional theory, and electrochemical analyses.

中文翻译：

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轴向手性稳定自由基：布拉特自由基阻转异构体的分辨率和表征

通过将 8-取代的 1-萘基锂加入 3-苯基和 3-叔丁基苯并[ e ][1,2,4]三嗪并通过手性高效液相色谱分离得到三个布拉特自由基的阻转异构体。它们的绝对构型是通过比较实验和时间相关的密度泛函理论计算的电子圆二色光谱来分配的。活化自由能 Δ G ^‡ ₂₉₈和外消旋半衰期t _1/2在 298 K 下测定为 ~25 kcal mol ^–1和 <130 小时，分别。单晶 X 射线衍射、密度泛函理论和电化学分析表明，自由基中的分子内 π-π 相互作用是显而易见的。