Carbon‐centered radicals are usually reactive and there are only few stable heteroatom‐centered organic radicals. Herein, we report a nitrogen‐centered bis(imino)perylene dimer based diradicaloid 2Per‐2 N, which has a large diradical character (y₀=72%) but still shows reasonable stability due to kinetic blocking of the aminyl radical sites by the bulky and electron‐deficient 2,4,6‐trichlorophenyl groups and effective spin delocalization. It displays thermally populated paramagnetic activity with a moderate singlet‐triplet energy gap (ΔE_S–T=−3.55 kcal/mol). Compared with a fully fused bis(imino)quaterrylene analogue (QR‐2 N) which is a typical closed‐shell compound, 2Per‐2 N possesses a much larger diradical character mainly due to the steric repulsion between the neighboring perylene units in the rigid quinoidal form. 2Per‐2 N exhibits a much smaller energy gap and longer absorption wavelength compared with QR‐2 N. 2Per‐2 N represents a rare example of stable nitrogen‐centered diradicaloid with a large diradical character.

中文翻译：

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稳定的以氮为中心的双（亚氨基）per二聚体基双自由基

以碳为中心的自由基通常是反应性的，只有很少的稳定的以杂原子为中心的有机自由基。在此，我们报道了一个以氮为中心的双（亚氨基）per二聚体基双自由基2Per-2 N，该双自由基具有较大的双自由基特征（y ₀ = 72％），但由于其对氨基自由基位点的动力学阻断，仍显示出合理的稳定性。庞大且缺乏电子的2,4,6-三氯苯基和有效的自旋离域作用。它显示了具有适中的单重态-三重态能隙（ΔE _S–T = −3.55 kcal / mol）的热填充顺磁活动。与典型的闭壳化合物完全融合的双（亚氨基）季戊四烯类似物（QR-2 N）相比，2Per-2 N具有较大的双自由基特性，这主要是由于刚性醌型形式的相邻per单元之间的空间排斥。与QR-2 N相比，2Per-2 N的能隙更小，吸收波长更长.2Per-2 N代表了一个稳定的以氮为中心的双自由基，具有大的双自由基特性的罕见例子。