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March 21

Dihydrogen (Monoxide)

I was thinking about the DHMO idiocy when I realized that while there are certainly chemicals where the IUPAC name ends in Monoxide, I can't come up with a single compound that starts with Dihydrogen that *isn't* an ion. There are ions like Dihydrogen phosphate as well as some where the Dihydrogen is in the middle like Sodium dihydrogen arsenate. I've also occasionally seen Dihydrogen used for H2 as opposed to HD. Is there anything in the IUPAC naming rules that make it so that a compound's name should never start with Dihydrogen?Naraht (talk) 12:27, 21 March 2021 (UTC)[reply]

One reason such names are uncommonly used is that the di- is often omitted for simplicity, because no similar molecule exists with a different number of hydrogen atoms. Examples are dihydrogen sulfide and dihydrogen selenide. - Lindert (talk) 13:29, 21 March 2021 (UTC)[reply]

Yup, the entire Hydrogen_chalcogenide grouping.Naraht (talk) 14:32, 21 March 2021 (UTC)[reply]

The majority of hydrogen-containing non-ionic compounds are organic, where hydrogens are virtually never mentioned (it's default assumption based on other name details). Using "dihydrogen" to indicate the H₂ unit is a good start. That leads to finding fun things like "dihydrogen endofullerene" (H₂@C₆₀). DMacks (talk) 16:41, 21 March 2021 (UTC)[reply]

And even for inorganic compounds with hydrogen, there is naming that already assumes hydrogen, eg sulfane for hydrogen sulfide, or monochloramine for H₂NCl, Difluorosilane for H₂F₂Si. For compounds where hydrogen is unexpected, you might use the term, eg argon dihydrogen cation ArH⁺
₂. Graeme Bartlett (talk) 22:39, 21 March 2021 (UTC)[reply]