Why is cyclo octatetraene non-aromatic?Please give a detailed explanation?

1 Answer
anor277
Feb 24, 2018

Does it fulfil the #"Huckel criterion"# for aromaticity?

Explanation:

And the #"Huckel criterion"# specifies #4n+2# #pi# electrons#"...."#delocalized around the ring... #"Cyclooctatetraene"# has #8*pi# electrons, the which in fact specifies an #"antiaromatic configuration"#...and since such configurations are inherently unstable under thermal conditions, the molecule bends to give a tub-shaped geometry which uncouples the #pi*"electrons"#.

On the other hand, #"cyclooctatetraene"#, can be easily reduced with 2 equiv of an alkali metal to give...#K_2^(+)[C_8H_8]^(2-)#. And this beast has #10*pi# electrons, the which fulfils the #"Huckel criterion"#, and planar COT dianion has an extensive coordination chemistry... So-called #"uranocene"-=[U(eta^8-C_8H_8)_2]# is a well-known sandwich complex....

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