 On the other hand the di-anion with 14 electrons is a Hückel aromat and more stable.According to in silico experiments the tri-trans isomer is expected to be the most stable, followed by the 1,7-ditrans and the all cis-isomers (+1 kcal/mol) and by the 1,5-ditrans isomer (+5 kcal/mol).The first [12]annulene with sym-tri-trans configuration was synthesized in 1970 from a tricyclic precursor by photolysis at low temperatures.