Itycene vs. Iptycenes 

First of all, thank you for your contribution to the article. When creating the article i was thinking about wheter to a sungular or plural form. A find the plural form more logical, since iptycene is a general name, several compounds with varying constitution qualify as an iptycene. I understand that e. g. arene and alkene articles are also in singular, but I don't really understand why. Is it simply a matter of agreement? Thank you.