Kato Kenichi, Furukawa Ko, Osuka Atsuhiro
Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo-ku Kyoto, 606-8502, Japan.
Center for Instrumental Analysis, Niigata University, Nishi-ku, Niigata, 950-2181, Japan.
Angew Chem Int Ed Engl. 2018 Jul 20;57(30):9491-9494. doi: 10.1002/anie.201804644. Epub 2018 Jun 21.
Trimethylenemethane (TMM) diradical is the simplest non-Kekulé non-disjoint molecule with the triplet ground state (ΔE =+16.1 kcal mol ) and is extremely reactive. It is a challenge to design and synthesize a stable TMM diradical with key properties, such as actual aliphatic TMM diradical centers and the triplet ground state with a large positive ΔE value, since such species provide detailed information on the electronic structure of TMM diradical. Herein we report a TMM derivative, in which the TMM segment is fused with three Ni meso-triarylporphyrins, that satisfies the above criteria. The diradical shows delocalized spin density on the propeller-like porphyrin π-network and the triplet ground state owing to the strong ferromagnetic interaction. Despite the apparent TMM structure, the diradical can be handled under ambient conditions and can be stored for months in the solid state, thus allowing its X-ray diffraction structural analysis.
三亚甲基甲烷（TMM）双自由基是具有三重态基态（ΔE = +16.1 千卡·摩尔）的最简单的非凯库勒非不相交分子，且具有极高的反应活性。设计并合成具有关键性质的稳定TMM双自由基是一项挑战，这些关键性质包括实际的脂肪族TMM双自由基中心以及具有较大正ΔE值的三重态基态，因为此类物种能提供有关TMM双自由基电子结构的详细信息。在此，我们报道了一种TMM衍生物，其中TMM片段与三个镍中-三芳基卟啉稠合，该衍生物满足上述标准。由于强铁磁相互作用，该双自由基在螺旋状卟啉π网络上表现出离域自旋密度以及三重态基态。尽管具有明显的TMM结构，但该双自由基可在环境条件下进行处理，并且可以固态形式储存数月，从而能够对其进行X射线衍射结构分析。
