Fig. 1: Reduction of [18]annulene with potassium.
From: The anti-aromatic dianion and aromatic tetraanion of [18]annulene
a, Structures of the dianion proposed in ref. 4. b, 1H NMR spectrum reported in ref. 4 (THF-d8, 60 MHz, −110 °C). c, 1H-13C heteronuclear single quantum coherence NMR spectrum (THF-d8, 500 MHz, −70 °C), and revised structural assignment of the dianion. Resonances a–f were assigned from the correlated spectroscopy (1H-1H COSY) spectrum (Supplementary Figs. 21 and 22).
