Octalene
Octalene is a polycyclic hydrocarbon composed of two fused cyclooctatetraene rings. Anions. Octalene can be readily reduced by lithium to a dianion and, unusually for such a small molecule, a tetraanion . The di-anion has its two negative charges in one ring, converting that ring into a 10-pi electron aromatic system similar to the di-anion of cyclooctatetraene. In the 18-pi electron tetra-anion, both rings effectively have access to 10 pi electrons, leading to a planar, bicyclic aromatic structure analogous to that of naphthalene.