This little thing is a monocyclic compound made from 4 carbon atoms and an arsenic atom (as well as 5 hydrogens)…

It bears the unfortunate name of arsole. I’m not even joking. Arsole is also, and I quote, “a mildly aromatic ring”. In fact, there are a whole series of these compounds that exist. That’s right — there are lots of arsoles out there. Technically, a whole family of arsoles.

If you feel the need to read about these arsoles, there are a few papers written about them!

• “Arsole Aromaticity Revisited”
  “The aromaticity of arsoles has been debated in the literature for years…”

• “Unusual Substitutions in an Arsole ring”
  It actually talks about “carbene insertions”!

• “Studies on the Chemistry of the Arsoles”
  G. Markl and H. Hauptmann, J. Organomet. Chem., 248 (1983) 269 (No web link, I’m afraid!)