Quadruple Anionic Buckybowls by Solid-State Chemistry of Corannulene and Cesium

[Image: see text] The buckybowl corannulene is known to be an excellent electron acceptor. UV photoelectron spectroscopy studies were performed with thin-film systems containing corannulene and cesium. Adsorption of submonolayer quantities of corannulene in ultrahigh vacuum onto thick Cs films, deposited at 100 K on a copper(111) substrate, induces a transfer of four electrons per molecule into the two lowest unoccupied orbitals. Annealing of thick corannulene layers on top of the cesium film leads to the formation of a stable film composed of C(20)H(10)(4–) ions coordinated to four Cs(+) ions. First-principles calculations reveal, as the most stable configuration, four Cs(+) ions sandwiched between two corannulene bowls.