What class of compounds does this belong to, if it exists; $$\ce{CH3-CH2-C\equiv N^{+}- CH3}$$ I honestly don't know if it exists; it popped up in my head while I was reading up on nitrile compounds, and I haven't heard of this type of molecule, thus the question.

If it doesn't exist, why not?

  • 4
    $\begingroup$ You appear to have a carbon with 5 bonds in there $\endgroup$
    – Waylander
    Commented May 2, 2021 at 7:16
  • $\begingroup$ @Waylander: Wouldn't it be $-C\equiv N-$? $\endgroup$
    – harry
    Commented May 2, 2021 at 7:21
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    $\begingroup$ Then you have a N with 4 bonds and no charge $\endgroup$
    – Waylander
    Commented May 2, 2021 at 7:47
  • 2
    $\begingroup$ Yes. Nitriles can be methylated by a variety of reagents. The N-methyl nitrilium species generated are highly reactive: example pubs.rsc.org/en/content/articlelanding/1980/c3/c39800001151/… $\endgroup$
    – Waylander
    Commented May 2, 2021 at 7:52
  • 3
    $\begingroup$ Just so you know, charges are never implied. $\endgroup$
    – Zhe
    Commented May 2, 2021 at 17:07

1 Answer 1


Compounds like this are named based on the nitrile from which they are derived. So, in your case, the nitrile is propanenitrile:


A protonated nitrile would be called a nitrilium cation, following the general form:

  • amine --> ammonium
  • imine --> iminium
  • nitrile --> nitrilium

Thus, the following cation is named propanenitrilium:


If we swap that proton with an alkyl group, we can call it an N-alkyl substituent. Thus, your cation is the N-methylpropanenitrilium cation.



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