Conjugated cyclic compounds Conjugated system

benzene orbitals



cyclooctatetraene. adjacent double bonds not coplanar.

cyclic compounds can partly or conjugated. annulenes, conjugated monocyclic hydrocarbons, may aromatic, non-aromatic or anti-aromatic.

aromatic compounds

conjugated, planar, cyclic compounds follow hückel s rule aromatic , exhibit unusual stability. classic example benzene has system of 6 π-electrons, forms benzene ring along planar σ-ring 12 electrons. benzene there 2 equivalent conjugated lewis structures, true molecular state quantum-mechanical combination of 2 structures 6 equivalent cc bonds intermediate between single , double bonds, , of equal length , strength.

non-aromatic compounds

not compounds alternating double , single bonds aromatic. cyclooctatetraene, example, possesses alternating single , double bonds. molecule typically adopts tub conformation. because p-orbitals of molecule not align in non-planar molecule, electrons not shared between carbon atoms. molecule can still considered conjugated, neither aromatic, nor antiaromatic (because not planar).