Talk:Bifluoride

Article title
Can someone explain to me why the article title is one word instead of two? It was moved from hydrogen difluoride to hydrogendifluoride because of "incorrect name." Is it considered an anion rather than a molecule, and is that the reason for the omission of the space? Hellbus 04:42, 3 November 2007 (UTC)


 * Yes. Hydrogen difluoride is salt nomenclature and implies a neutral compound, HF2, which does not exist. The lack of a space between hydrogen and difluoride is also seen in, for example, name hydrogencarbonate for HCO3−.


 * If someone knows a more appropriate or widely-used name for this article, they can go right ahead and change it.


 * Ben 13:05, 3 November 2007 (UTC)


 * Thanks. I'm going to add a note to the article explaining why there's no space. Hellbus 16:41, 3 November 2007 (UTC)

I've been thinking about this and I'm getting more convinced that the name should have a space. First, because here are all the alternative names listed by chemical abstracts (registry number 18130-74-0):


 * CA Index name: Fluoride (HF21-) (8CI,9CI)
 * Other names: Bifluoride; Bifluoride (HF2-); Bifluoride (HF21-); Bifluoride anion (HF21-); Fluoride (HF2-); Hydrogen bifluoride ion(1-); Hydrogen difluoride (HF21-); Hydrogen difluoride anion; Hydrogen difluoride ion(1-); Hydrogen difluoride(1-); Hydrogen fluoride (HF21-); Hydrogen fluoride ion (HF21-)
 * I think (HF21-) should have been HF2(1-).
 * I propose removal of the link to http://www.chemspider.com/Chemical-Structure.35308425.html as it shows the wrong formula H2F2 and more information is practically absent there.
 * Simon de Danser (talk) 13:47, 30 September 2020 (UTC)

Notice that none of them have the word hydrogendifluoride. I think that the reason the space was deleted was an analogy with the way the names of anions such as hexafluoroplatinate are constructed. However, upon closer inspection one sees that hydrogendifluoride is not constructed in the same way! By that analogy, it should be called something like difluorohydrogenate, which is not even in the list of options. I suggest reverting back to hydrogen difluoride, or to hydrogen difluoride anion or bifluoride. —Preceding unsigned comment added by Itub (talk • contribs) 13:05, 5 November 2007 (UTC)


 * I just looked at the IUPAC recommendations, and I think that the relevant ones are sections 8.4 and 8.5 of this document. In short, if one chooses to use a "hydrogen name" (which is not the only possible "IUPAC name"), the anion part of the name should be in brackets, as in hydrogen(difluoride). Per section 8.5, some common names, such as hydrogencarbonate, are exempt from the bracket requirement. But hydrogendifluoride is not on the list. I stand by my previous recommendations, but in any case if we really wanted to use the IUPAC "hydrogen name", it should be hydrogen(difluoride). --Itub 13:38, 5 November 2007 (UTC)

First I think that the word "anion" must be included, to avoid any suggestion that the name represents a neutral molecule. For the 3 names that I would consider, a Google search shows 295 for bifluoride anion, 82 for hydrogen difluoride anion, and 10 for hydrogendifluoride anion. Without the word "anion" (and therefore including salts), Google gives 119 000 for bifluoride, 11 900 for hydrogen difluoride, and 696 for hydrogendifluoride. This would suggest using Bifluoride as title, with redirects and mentions on the first line for the other two. As for the Bicarbonate article.

Comments on other sources: CA clearly gives too many names, perhaps to ensure that its readers can find even articles with incorrect names. Several of their names actually refer to other species (fluoride F-, hydrogen fluoride HF, hydrogen fluoride ion HF- or HF+)

IUPAC's examples all have terminal hydrogens. Hydrogen(difluoride) would imply an H attached to an F-F unit, which is not the case. If IUPAC does not mention HF2- specifically I would not use them as a source.

And finally I consulted 3 well-known Inorganic Chemistry texts. All 3 avoid the problem by citing only the formula HF2- with no name. OK for texts but not for an encyclopedia I think. Dirac66 04:00, 7 November 2007 (UTC)


 * Good points, sounds like bifluoride is the way to go. I tried to move the page there initially, but there's already a redirect there, so can an admin do it?


 * I would like to add fluorohydrogenfluoride anion to the candidates list.

Simon de Danser (talk) 13:53, 30 September 2020 (UTC)


 * Ben 08:08, 7 November 2007 (UTC)


 * We could move it to Bifluoride anion without an admin, if that is agreeable. Regarding Dirac66's comment about CAS "other names": I don't think they are incorrect, but just rather unusual systematic names of some sort. They don't call this ion fluoride, but fluoride (HF2-). That is, I think the part of the name in parenthesis is important. I imagine this naming scheme is a remnant of the days when one had to actually search alphabetically through the tomes of the CAS index. --Itub 09:00, 7 November 2007 (UTC)

One more source: The Merck Index (13th edn, 2001) does not list anions, but lists salts including Ammonium Bifluoride, Potassium Bifluoride, Sodium Bifluoride. Dirac66 22:09, 1 December 2007 (UTC)

--Bounty braveheart (talk) 10:56, 6 January 2011 (UTC) Read better note 3) [Pimentel, G. C. The Bonding of Trihalide and Bifluoride Ions by the Molecular Orbital Method. J. Chem. Phys. 1951, 19, 446-448. ]. H can bond only to one other atom (exept for metallic-hydrogen), so the correct bonding scheme should be F-H σ bond between an hydrogen s orbital and a fluoron p orbital and two F atoms bonded toghether by a π bond between two p orbitals F-F ; so the whole ione form would be H-F-F-. Waiting for somone else to review the correctness of my writing I won't change the Article for unless 15 days.


 * Suggest you brush up on your chemistry. Hydrogen can bond to more than one other thing - check out diborane for example. The article is fine as it is. Chris (talk) 15:14, 6 January 2011 (UTC)

Chemical Properties
I noticed while reading this article that the second chemical equation under "Basicity", the one about most bifluorides being dissociated in solution, is unbalanced. There are 2 fluorines on the left, but only 1 on the right. Also, the charge is unbalanced, since the left has a net 1- charge, but the right has no net charge. I don't know what the correct equation is, so I won't edit it yet, but it seems clear that it can't be correct at present. Any ideas? Skeletoroforange (talk) 04:22, 25 September 2014 (UTC)


 * Fixed, thank you. Plasmic Physics (talk) 08:31, 25 September 2014 (UTC)