Site‐Specific Reduction‐Induced Hydrogenation of a Helical Bilayer Nanographene with K and Rb Metals: Electron Multiaddition and Selective Rb+ Complexation. (16th December 2021)

• Record Type: Journal Article
• Authors: Zhou, Zheng; Fernández‐García, Jesús M.; Zhu, Yikun; Evans, Paul J.; Rodríguez, Rafael; Crassous, Jeanne; Wei, Zheng; Fernández, Israel; Petrukhina, Marina A.; Martín, Nazario
• Is Part Of: Angewandte Chemie. Volume 134:Number 10(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-12-16
• Subjects: Chemical reduction -- DFT calculations -- Helical bilayer -- Hydrogenation -- X-ray crystallography; Chemistry -- Periodicals; 540
• DOI: 10.1002/ange.202115747
• Languages: English
• ISSNs: 0044-8249

Abstract

Abstract: The chemical reduction of π‐conjugated bilayer nanographene 1 (C138 H120 ) with K and Rb in the presence of 18‐crown‐6 affords [K + (18‐crown‐6)(THF)2 ][{K + (18‐crown‐6)}2 (THF)0.5 ][C138 H122 3− ] (2 ) and [Rb + (18‐crown‐6)2 ][{Rb + (18‐crown‐6)}2 (C138 H122 3− )] (3 ). Whereas K + cations are fully solvent‐separated from the trianionic core thus affording a "naked" 1 .3 − anion, Rb + cations are coordinated to the negatively charged layers of 1 .3 − . According to DFT calculations, the localization of the first two electrons in the helicene moiety leads to an unprecedented site‐specific hydrogenation process at the carbon atoms located on the edge of the helicene backbone. This uncommon reduction‐induced site‐specific hydrogenation provokes dramatic changes in the (electronic) structure of 1 as the helicene backbone becomes more compressed and twisted upon chemical reduction, which results in a clear slippage of the bilayers. Abstract : An unprecedented site‐specific reduction‐induced hydrogenation of a helical bilayer nanographene has been found using K or Rb metals. However, coordination of the metal to the central six‐membered rings of the bilayer helicene in a η 3 ‐mode is only observed for the Rb complex, due to its larger ionic size, thus showing the impact of the cation's size on the reaction product.