# Ring compounds of non-carbon atoms [closed]

Are there compounds that are rings of non-carbon atoms, say a ring of six oxygen atoms, or 5-6 nitrogen atoms with attached hydrogens? Or are these too unstable to exist for long (if at all), like long oxygen chains ($\ce{HO_{n}H}$)?

• – Jan Jun 17 '16 at 17:30
• Are you looking for a single element around the ring? Otherwise borazine would count: en.wikipedia.org/wiki/Borazine – jerepierre Jun 17 '16 at 17:32
• Sulphur forms many cyclic allotropes, and phosphorous has some as well. – bon Jun 17 '16 at 17:34
• There are many common rings with more than one element in them and no carbons. Single element rings seem harder. – matt_black Jun 17 '16 at 19:22
• Good answers so far. Anyone know anything about rings of Oxygen? It wouldn't be aromatic since there wouldn't be any bonds left over. Right? – Justsalt Jun 17 '16 at 19:44

Pentazole exists - an $\ce{N5H}$ ring. It is stabilised by aromaticity, with 6 $\pi$-electrons in a cyclic, planar system.

Sulphur forms many allotropes which are rings but these do not contain hydrogen. $\ce{S8}$ and $\ce{S7}$ are the most common.

Phosphorus also forms cyclic allotropes such as white phosphorous, $\ce{P4}$.

DavePhD also mentioned in his answer that a silicon analogue of benzene has been synthesised recently but it is not $\ce{Si6H6}$ because it has other groups attached to some of the silicon atoms.

• Pentazole does not quite exist. I mean, well, it kinda does, but that's not quite the same kind of "exists" as benzene or anything... – Ivan Neretin Jun 17 '16 at 20:03
• I doubt that counting lone pairs in pentazole is good idea here. Also many substituted ones are more stable. – Mithoron Jun 17 '16 at 21:36
• Not 10 $\pi$ electrons. Only six, isoelectronic with pyrrhole. – Oscar Lanzi Jun 17 '16 at 23:31
• @OscarLanzi Oh yes sorry my mistake. – bon Jun 18 '16 at 8:21
• You can also have $S_8$: upload.wikimedia.org/wikipedia/commons/thumb/f/f1/… – timaeus222 Jun 18 '16 at 21:06

Chemists in the UK have constructed a structural analogue of benzene made from silicon atoms. The molecule is not flat like benzene, but it reveals a new type of aromatic stabilisation.

Do not forget the trihydrogen cation (https://en.wikipedia.org/wiki/Trihydrogen_cation, https://en.wikipedia.org/wiki/Triatomic_hydrogen). This has been found in the interstellar medium and in hydrogen-rich planetary atmospheres, and is believed to be responsible for the formation of early-generation stars.

• The trihydrogen cation is an interesting case. Though you can draw a triangular ring between the nuclei, as far as I understand the highest electron density is actually at the centre of the resulting triangle, so you could think of it more like three atoms joined by a Y-shaped bond than a ring. – Nicolau Saker Neto Jun 18 '16 at 2:00