Abstract
The chemical reduction of π-conjugated bilayer nanographene 1 (C(138) H(120) ) 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) ][C(138) H(122) (3-) ] (2) and [Rb(+) (18-crown-6)(2) ][{Rb(+) (18-crown-6)}(2) (C(138) H(122) (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.