Cyclooctatetraenide

Cyclooctatetraenide refers to the dianion of cyclooctatetraene. Cyclooctatetraene itself is a cyclic organic compound with the formula C8H8. It is a conjugated annulene that, in its neutral form, is non-aromatic. However, when cyclooctatetraene accepts two electrons, it forms the cyclooctatetraenide dianion, C8H8^2-. This dianion is aromatic.

The aromaticity of the cyclooctatetraenide dianion is a significant aspect of its chemistry. According to Hückel's rule, aromaticity is achieved by planar cyclic systems with (4n+2) pi electrons. The cyclooctatetraenide dianion has eight pi electrons, which fits the 4n+2 rule with n=1, assuming it adopts a planar conformation. Experimental evidence, such as NMR spectroscopy, supports its aromatic character and planar geometry.

Cyclooctatetraenide dianions are typically formed by the reduction of neutral cyclooctatetraene. This reduction can be achieved using strong reducing agents, such as alkali metals (like sodium or potassium) in appropriate solvents. The resulting dianion is a resonance-stabilized species. It can be isolated as salts with counterions, such as alkali metal cations. The chemistry of cyclooctatetraenide dianions is of interest in understanding aromaticity and the reactivity of conjugated cyclic systems.