Supramolecular trap for a transient corannulene trianion

The first structural characterization of the transient triply-reduced state of corannulene (C(20)H(10)) is accomplished. The X-ray crystallographic study reveals that the C(20)H(10)˙(3–) trianions, generated by corannulene reduction with metallic cesium, form a novel type of supramolecular sandwich-type assembly, [Cs(+)//(C(20)H(10)(3–))/4Cs(+)/(C(20)H(10)(3–))//Cs(+)]. In the product, two triply-charged corannulene decks encapsulate a rectangle of four cesium ions with the external concave bowl cavities being filled by one cesium ion each. The structural investigation is augmented by in-depth theoretical calculations to provide insights into the geometrical features and electronic structure of this unique organometallic self-assembly.