In the following image, $\mathrm{CH}_2$ is connected to benzene rings with a $-\equiv-$ like symbol. What's the meaning of this symbol?

Organic chemistry powered double-barrier resonant tunneling diode


1 Answer 1


This is a triple bond between two $\ce{C}$ atoms, i.e. $\ce{-C#C -}$. It is drawn that way because the carbon atoms in a triple bond are $\mathrm{sp}$-hybridised and thus exhibit a linear arrangement.

  • $\begingroup$ If this is a triple bond, then why here the benzene rings are with a single bond? $\endgroup$
    – Sparkler
    Dec 2, 2014 at 0:50
  • $\begingroup$ @Sparkler Sorry, I don't understand your question. Benzene rings can only directly be linked by a single bond, because you can't have a carbon atom with 5 bonds (notwithstanding very rare exceptions). If you link them via a carbon chain then this chain can contain single, double or triple bonds. $\endgroup$
    – Philipp
    Dec 2, 2014 at 1:06

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.