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I have been studying nomenclature and was asked to find the name of a strange compound: $\ce{H2S4O}$.

In my opinion, it should be dihydrogen-tetrasulfur oxide which seems very weird.

Can somebody advise me on how to name this compound (and whether this compound really exists?, I was able to come up with a structure similar to benzene...)

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    $\begingroup$ Could it by a type and it's H2SO4? $\endgroup$ – DSVA Sep 7 '17 at 20:21
  • $\begingroup$ Yeah it could be but I dont think so because H2SO4 has appeared once and so had H2SO3 in the previous questions. $\endgroup$ – mathnoob123 Sep 7 '17 at 20:25
  • $\begingroup$ Your name is wrong, but there's too much isomers possible. Unless one of them is only relatively stable or otherwise obvious choice, this is too broad. $\endgroup$ – Mithoron Sep 7 '17 at 22:40
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    $\begingroup$ It looks like a typo to me, e.g. it's either a sulfuric acid $\ce{H2SO4}$, or one of the polysulfuric acids: $\ce{H2S4O6}$, $\ce{H2S4O13}$. $\endgroup$ – andselisk Sep 8 '17 at 0:27
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Section IR-5.4 of IUPAC’s Nomenclature of Inorganic Compounds (Red Book) of 2005 lists the rules that shall apply to naming inorganic compounds by a generalised stoichiometric name which does not carry any information about the compound’s structure. These rules dictate that:

The constituents of the compound to be named are divided into formally electropositive and formally electronegative constituents. There must be at least one electropositive and one electronegative constituent. Cations are electropositive and anions electronegative, by definition. Electropositive elements occur later in Table VI than electronegative elements by convention.

In principle, the division into electropositive and electronegative constituents is arbitrary if the compound contains more than two elements. In practice, however, there is often no problem in deciding where the division lies.

Section IR-5.4.1

In our case, oxygen must be considered electronegative and hydrogen must be considered electropositive since they have the highest and lowest electronegativity, respectively.

Within the classes of electronegative or electropositive substituents, ordering is strictly alphabetical. Electropositives come first, electronegatives last.

Section IR-5.4.2.1 allows the use of multiplicative prefixes as is the case with binary compounds. Further information such as charge, oxidation numbers or structure is not at our disposal.

Therefore, according to the principles laid out, we have two choices to name $\ce{H2S4O}$, depending on whether we wish to consider sulphur electropositive or electronegative:

  • Dihydrogen tetrasulphur oxide

  • Dihydrogen oxide tetrasulphide


To the best of my knowledge, this compound does not exist. But the principles of nomenclature are designed in a way to allow the naming of all compounds whether synthesised, hypothesised or fancily drawn on paper.

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As noted in the comments, this is most likely a typo. In any event, if existent, this should probably regarded as an acid and thus could be called trithiosulfuric acid, following its cousin thiosulfuric acid.

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