The 6:6 ring bonds (between two hexagons) can be considered " double bonds" and are shorter than the 6:5 bonds (between a hexagon and a pentagon).
Izibopho ze-6: 6 (phakathi kwamahektha amabili) zingacatshangwa "izibopho ezimbili" futhi zifushane kunezibopho ezingu-6: 5 (phakathi kwehektaregi ne-pentagon).