Jahn-Teller effect in circulenes: X-ray diffraction study of coronene and corannulene radical anions.

Single-crystal X-ray diffraction studies of two polyaromatic radical anions crystallized as sodium salts, namely [Na(DME)(3) ](+)[C(20) H(10)(-)] (1) and [Na(DME)(3)](+)[C(24)H(12)(-)] (2) are reported. This allowed the first structural evaluation of Jahn-Teller (JT) effects for monoreduced circulenes and a comparison between bowl-shaped corannulene and planar coronene. The C(s) and D(2h) symmetrical distortions are found to fit the experimental data for C(20)H(10)(·-) and C(24)H(12)(·-), respectively. The continuous symmetry measure (CSM) analysis was carried out to provide a quantitative measure of the JT distortions in 1 and 2. In addition, the X-ray crystallographic results were fully supported by DFT calculations.