Mono‐reduced Corannulene: To Couple and Not to Couple in One Crystal
Mono‐reduced Corannulene: To Couple and Not to Couple in One Crystal
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单还原冠环烯：在一个晶体中耦合和不耦合
DOI：
10.1002/chem.201902992
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发表时间：
2019
期刊：
影响因子：
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通讯作者：
Petrukhina, Marina A.
中科院分区：
文献类型：
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作者：
Rogachev, Andrey Yu.;Alkan, Melisa;Li, Jingbai;Liu, Shuyang;Spisak, Sarah N.;Filatov, Alexander S.;Petrukhina, Marina A.
单晶X-射线衍射法表明，C20H10在二甘醇中与锂金属发生单电子还原反应生成[{Li+(diglyme)2}4(C20H10.−)2(C20H10‐C20H10)2−](1)。这种混合产品含有两个棒烯单阴离子自由基和一个双阴离子二聚体，由四个锂离子包裹在二甘醇分子中结晶而成。二聚体(C20H10-C20H10)2−阴离子提供了第一个从结晶学上证实的C20H10.−的自发自由基二聚的例子。两个C20H10..−碗之间的C-−C键长度为1.588(5) ？与接头的单σ键特征一致。在中心对称的(C20H10-C20H10)2−二聚体中观察到两个碗的相互配置，中心C−C键的扭转角为180°。对二聚双阴离子的形成/分解过程进行了全面的理论分析，以评价C20H10.−偶联的成键性质和能量学性质。研究发现，这种σ键合的二聚体由于制备能量大和成键中的泡利排斥成分，在热力学上是不稳定的，但由于现有的自旋交叉点提供了高能垒，所以在动力学上是持久的。
One‐electron reduction of corannulene, C20H10, with Li metal in diglyme resulted in crystallization of [{Li+(diglyme)2}4(C20H10.−)2(C20H10‐C20H10)2−] (1), as revealed by single‐crystal X‐ray diffraction. This hybrid product contains two corannulene monoanion‐radicals along with a dianionic dimer, crystallized with four Li+ions wrapped by diglyme molecules. The dimeric (C20H10‐C20H10)2−anion provides the first crystallographically confirmed example of spontaneous radical dimerization for C20H10.−. The C−C bond length between the two C20H10.−bowls of 1.588(5) Å is consistent with the single σ‐bond character of the linker. Thetrans‐disposition of two bowls in the centrosymmetric (C20H10‐C20H10)2−dimer is observed with the torsion angle around the central C−C bond of 180°. Comprehensive theoretical analysis of formation/decomposition processes of the dimeric dianion has been carried out in order to evaluate the nature of bonding and energetics of the C20H10.−coupling. It is found that such σ‐bonded dimers are thermodynamically unstable due to large preparation energy and repulsive Pauli component of the bonding, but kinetically persistent due to a high energy barrier provided by the existing spin‐crossing point.