aromaticity:
- stabilising effect because spreading electrons over a greater number of atoms/volume electron-electron repulsion is minimised
conditions for aromaticity:
- cyclic molecule
- planar
- fully conjugated
- huckel’s rule [4n+2]
electrons - 4n is anti-aromatic
anti-aromatic molecules tend to distort/warp out of shape to avoid having unpaired electrons in degenerate higher energy MOs jahn-teller distortion
- cyclobutadiene → one corner higher
- cyclooctatetraene → tub shape or Z shape
planar:
- due to requirement of side by side overlap of
orbitals - if distorted from planar, poor overlap results in breaking of bonds
- frost circle
