Mono-reduced Corannulene: To Couple and Not to Couple in One Crystal |
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Authors: | Prof?Dr Andrey Yu Rogachev Melisa Alkan Dr Jingbai Li Shuyang Liu Dr Sarah N Spisak Dr Alexander S Filatov Prof?Dr Marina A Petrukhina |
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Institution: | 1. Department of Chemistry, Illinois Institute of Technology, Chicago, IL 60616 USA;2. Department of Chemistry, University at Albany, State University of New York, Albany, NY, 12222 USA |
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Abstract: | 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. The trans-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. |
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Keywords: | chemical reduction corannulenes molecular structures radicals X-ray diffraction |
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