Parquet compounds on the basis of eight- and twelve-membered structure blocks: Quantum-chemical study

Annelated structures of cyclooctatetraene and cyclododecahexene and their expanded lowmolecular derivatives were studied using DFT B3LYP method with 6-311G(d,p), 6-311(df,p), 6-311+G(3df) basis sets. Monomer systems including planar antiaromatic cycles are stable in the singlet state, whereas the corresponding triplet states are significantly destabilized. The stability of nonstandard planar forms with antiaromatic cycles is provided by steric factors and the effects of π-electron interaction between the central and peripheral fragments.