Zhou Mingfei, Xu Qiang, Wang Zhi-Xiang, Schleyer Paul von Ragué
Department of Chemistry, Fudan University, Shanghai 200433, P.R. China.
J Am Chem Soc. 2002 Dec 18;124(50):14854-5. doi: 10.1021/ja027865s.
A new sigma-pi diradical, B4(CO)2, prepared in matrix isolation, was characterized unambiguously by isotopic-substitution infrared spectroscopy and by theoretical computations. Both open-shell singlet and triplet states have three pi electrons but are aromatic with moderately large NICS values. Quantum chemical calculations at various levels indicate that the open-shell singlet is slightly more stable than the triplet state. However, the singlet and triplet are computed to have very similar IR features which do not allow experimental differentiation.
一种新的σ-π双自由基B4(CO)2，在基质隔离条件下制备而成，通过同位素取代红外光谱和理论计算得到了明确表征。开壳单重态和三重态都有三个π电子，但具有中等较大的核独立化学位移（NICS）值，呈芳香性。不同水平的量子化学计算表明，开壳单重态比三重态稍微稳定一些。然而，计算得出单重态和三重态具有非常相似的红外特征，无法通过实验进行区分。
