一个由南京工业大学赵莉莉教授与Gernot Frenking教授领导的国际合作小组，首次制备出可分离的含重碳（dicarbon, C₂）基团的化合物。 该研究于2020年11月30日发表于《自然-化学》杂志。

与天然存在的F₂、O₂和N₂不同，双原子重碳C₂是一种此前仅在气相中被间接观测到的神奇物质，其高反应活性使其在凝聚态中极难被分离。虽然之前已有L→C₂←L型化合物的报道，但其中C₂的成键方式（类似“偶碳”）与自由C₂有很大不同。在该文中，研究人员合成并结构表征了一种含双原子重碳C₂的化合物，其中C₂以L→C₂的单配位复合物形式存在，而配体L是由含两个咪唑烷-2-亚胺的大位阻膦构成的（化学式(NHC^R=N)₂(CH₃)P，其中NHC^R为一种氮杂环卡宾）。

进一步研究表明，该化合物室温下可在溶液中稳定存在，且可以固态形式被分离出来。对该化合物的反应性研究及量子化学分析表明，L→C₂复合物中的两个碳原子均具有卡宾的特性。此外，该化合物在热解时可发生分子间C-H键活化，并在与甲醇反应时表现出类似氢烷氧基化的反应活性。

附：英文原文

Title: Isolable dicarbon stabilized by a single phosphine ligand

Author: Tsz-Fai Leung, Dandan Jiang, Ming-Chun Wu, Dengmengfei Xiao, Wei-Min Ching, Glenn P. A. Yap, Tao Yang, Lili Zhao, Tiow-Gan Ong, Gernot Frenking

Issue&Volume: 2020-11-30

Abstract: In contrast to naturally occurring F2, O2 and N2, diatomic C2 is an intriguing species that has only been observed indirectly in the gas phase, and because of its high reactivity has eluded isolation in the condensed phase. It has previously been stabilized in L→C2←L compounds but the bonding situation of the central C2 in this motif differs remarkably from that of free C2. Here we have prepared and structurally characterized diatomic C2 as a monoligated complex L→C2 using a bulky phosphine ligand bearing two imidazolidin-2-iminato groups (L is (NHC^R=N)₂(CH₃)P, where NHC^R is an N-heterocyclic carbene). The compound is stable in solution at ambient temperature and has also been isolated in the solid state. Reactivity studies, in combination with quantum chemical analysis, suggest that the two carbon atoms of the L→C2 complex both have carbene character. The complex underwent intermolecular C–H bond activation upon thermolysis and exhibited hydroalkoxylation-like reactivity with methanol.

DOI: 10.1038/s41557-020-00579-w

Source: https://www.nature.com/articles/s41557-020-00579-w