Nitrene radical compounds are short-lived intermediates in a variety of nitrogen-involved transformations. They feature either a singlet or a triplet ground state, depending on the electronic properties of the substituents. Triplet nitrenes are highly reactive and their isolation in the condensed phase under ambient conditions is challenging. Here we report the synthesis and isolation of a triplet arylnitrene supported by a bulky hydrindacene ligand. The arylnitrene is fully characterized by various spectroscopic and structural techniques including electron paramagnetic resonance spectroscopy and single-crystal X-ray diffraction. Its high stability is largely attributed to the steric hindrance and effective electron delocalization provided by the supporting ligand. Electron paramagnetic resonance spectroscopy in conjunction with highly correlated wavefunction-based ab initio calculations provides support for a triplet ground state nitrene with axial zero-field splitting D = 0.92 cm^–1 and vanishing rhombicity E/D = 0.002.

硝酸自由基化合物是各种含氮转化的短寿命中间体。它们具有单重态或三重态基态，具体取决于取代基的电子特性。三重态硝酸酯具有很高的反应性，在环境条件下它们在凝聚相中的分离具有挑战性。本文报道了由大体积肼配体支持的三联态芳基腈的合成和分离。芳基腈通过各种光谱和结构技术得到充分表征，包括电子顺磁共振光谱和单晶 X 射线衍射。它的高稳定性主要归因于支持配体提供的空间位阻和有效的电子离域。电子顺磁共振波谱与高度相关的基于波函数的从头计算相结合，为具有轴向零场分裂 D = 0.92 cm^–1 和消失菱形 E/D = 0.002 的三重态基态氮提供支持。