[Gameofketones]

Are odd numbered carbons possible in annulenes? Annulenes must be conjugated so are odd rings possible?

[clarkstill]

By the IUPAC definition they are, but odd numbered ones have the formula CnH(n+1), which isn’t fully conjugated. More intuitively I’d call the cyclopentadienyl anion and the tropylium cation annulenes, but looking at the definition I’m not sure that they are!