Hi, I need suggestions for a nomenclature problem.  Please forgive the boring long explanation below.<br/>I have been working on [[methylene]] and related articles.  There are three fairly common meanings for the word:
:(1)the free molecule ''':'''{{chem|CH|2}}, officially called "carbene";
:(2)the 'terminal' functional group ={{chem|CH|2}}, connected to a single atom by a double bond;
:(3)the 'bridging' functional group -{{chem|CH|2}}-, connected to two different atoms by single bonds.
Until recently there was one article called <nowiki>[[</nowiki>methylene<nowiki>]]</nowiki> for sense (1), with chembox and everything, that briefly mentioned senses (2) and (3); and a page called <nowiki>[[</nowiki>methylenes<nowiki>]]</nowiki> that was basically a disambiguation page (only a couple of lines for each sense) but not tagged as such.<br>Now there are separate pages for senses (2) [[methylene group]] and (3) [[methylene bridge]].  Those pages are only stubs now but I believe that there is enough material to write books on them (bond geometry, electronic structure, reactions, spectroscopy, etc.)<br>There is also a [[methylene (disambigution)]], that can be reached via the link "for other uses see..." in <nowiki>[[</nowiki>methylene<nowiki>]]</nowiki>.<br>Then I went through almost all links to <nowiki>[[</nowiki>methylene<nowiki>]]</nowiki> and <nowiki>[[</nowiki>methylenes<nowiki>]]</nowiki> to resolve them to the proper page.  Of ~130 links, I found 91 that were actually for the bridge, 22 for the terminal group, about 10 (lost the exact count) that were indeed for the free molecule, and 5 that I could not figure out ([[Cyclophane]] [[Johnson–Corey–Chaykovsky reaction]] [[Organoselenium chemistry]] [[Persistent carbene]] [[Tröger's base]]).</br>So it seems that
:(A) as long as the article on the molecule is called just <nowiki>[[</nowiki>methylene<nowiki>]]</nowiki>, we can expect that ~90% of the <nowiki>[[</nowiki>methylene<nowiki>]]</nowiki> links that will be created in the future by busy or lazy editors will be wrong. The reader who clicks on the link because he doesn't know the term will be quite confused; and since experts will not click there, the link will never be corrected.  My conclusion: the article about the molecule ''must'' be renamed to a more specific name.
:(B) Renaming <nowiki>[[</nowiki>methylene bridge<nowiki>]]</nowiki> to be just <nowiki>[[</nowiki>methylene<nowiki>]]</nowiki> would be convenient and result in correct link in ~70% of the cases. However, perhaps 30% of the new links may still end up pointing to the wrong sense of the word.  My conclusion: neither sense should be the "primary" sense.
:(C) The remaining alternative is to let <nowiki>[[</nowiki>methylene<nowiki>]]</nowiki> be the disambiguation page.  Then new links <nowiki>[[</nowiki>methylene<nowiki>]]</nowiki> created by busy or lazy editors will end up pointing to a disamb page. This sounds bad, but such links can be detected by bots and will soon get fixed.  Misdirected links will not.
I hope this plan is OK. Note that there are already two articles for CH3, [[methyl group]] and [[methyl radical]].  My question is what to call the current <nowiki>[[</nowiki>methylene<nowiki>]]</nowiki> article (about the molecule). Here are some ideas:
:(a) <nowiki>[[</nowiki>Methylene radical<nowiki>]]</nowiki>. This would follow the precedent of <nowiki>[[</nowiki>Methyl radical<nowiki>]]</nowiki>. Unfortunately "radical" my mean "bound group", so the confusion would continue.
:(b) <nowiki>[[</nowiki>Methylene (free radical)<nowiki>]]</nowiki>.  Very clear and unambiguous, and fits Wikipedia general rules. However, I have been told that "radical" is now defined by the IUPAC and depends on spin state, and  ''':'''{{chem|CH|2}} does not qualify.  Is it so?
:(c) <nowiki>[[</nowiki>Methylene molecule<nowiki>]]</nowiki> Never used in Wikipedia for any other page on chemical species.
:(d) <nowiki>[[</nowiki>Methylene (molecule)<nowiki>]]</nowiki> Ditto.
:(e) <nowiki>[[</nowiki>Methylene (carbene)<nowiki>]]</nowiki> This would be doubly correct since methylene is '''a''' carbene and also "carbene" is its quasi-official name.  But in Wikipedia one does not call articles <nowiki>[[</nowiki>name (another name)<nowiki>]]</nowiki>. Also that title would be obscure to many readers and editors.
:(f) [[Carbene]] Very correct, but unfortunately it is taken by the carbene family
:(g) <nowiki>[[</nowiki>Methylene (chemical species)<nowiki>]]</nowiki> Too long, and maybe obscure to editors.
Any other suggestions? My favorite is (b) <nowiki>[[</nowiki>Methylene (free radical)<nowiki>]]</nowiki>. If "radical" is OK for methyl, why not for methylene? IUPAC be damned!<br/>What do you say? All the best, --~~~~