Stepwise Generation of Mono-, Di-, and Triply-Reduced Warped Nanographenes: Charge-Dependent Aromaticity, Surface Nonequivalence, Swing Distortion and Metal Binding Sites
Sarah N. Spisak, Zheng Zhou, Shuyang Liu, Qi Xu, Zheng Wei, Kenta Kato, Yasutomo Segawa, Kenichiro Itami, Andrey Yu. Rogachev, Marina A. Petrukhina*
Angew. Chem. Int. Ed. 2021, Early View. DOI: 10.1002/anie.202110748
The stepwise chemical reduction of molecular warped nanographene (WNG) having a negatively curved π -surface and defined C 80 H 30 composition with Cs metal used as the reducing and complexing agent allowed the isolation of three different reduced states with one, two, and three electrons added to its π -conjugated system. This provided a unique series of contorted nanosized carbanions with increasing negative charge for in-depth structural analysis of consequences of controlled electron charging of non-planar nanographenes, using X-ray crystallographic and computational tools. The 3D molecular electrostatic potential (MEP) maps identified the negative charge localization at the central part of the WNG surface where selective coordination of Cs + ions has been confirmed crystallographically. In-depth theoretical investigation revealed a complex response of WNG to the stepwise electron acquisition. The extended and contorted π -surface of WNG undergoes subtle swinging distortions that are accompanied by notable changes in the electronic structure and site-dependent aromaticity of the resulting nanosized carbanions.