Talk:Rosocyanine

Image correction

I request corrections to the image Rosocyanine.png. According to one of the given references, Spicer, G. S.; Strickland, J. D. H. Compounds of Curcumin and Boric acid. Part I. The structure of rosocyanin Journal of the Chemical Society (London), 1952, 4644-4650, the structure is like the bottom one shown, but there is a negative charge on boron. The counterion is an H+ on one of the quinone oxygens. In addition, there is an H+ on the other quinone oxygen, with a Cl- counterion. So of the various ways to accurately depict the structure, the easiest way is to start with the bottom structure now there, label the B with a negative sign, put an H on each of the quinone oxygens (=OH), label those oxygens with positive signs, and take away the brackets and the circle-positive sign, now that the positive charges are localized. The chloride could stay where it is, since it's near one of the quinone oxygens which now get positive signs, or it could be moved closer to that positive sign.

I think it's better to draw localized charges and bonds, e.g., benzene as 1,3,5-cyclohexatriene. It's not a completely accurate representation of reality, but it's easier to count bonds and electrons and atoms that way. So my preference would be to just show one structure: the bottom one, with the changes I suggested.HowardJWilk (talk) 02:05, 29 July 2011 (UTC)

I agree that the bottom structure as-is does not look correct (only 18H per ligand). The idea of protonating the quinone O and formal +, and a formal – on B, sounds like a pretty good reflection of the bonding and something about the charge. Using the horse-shoe form of the 1,3-dicarbonyl makes that part of the ligand approximtely –1 (deprotonated acetylacetone). Or else that as the Lewis-structure idea, with each ligand acting as [C–O–B and C=O→B], puts the molecular +1 in the O→B vicinity. DMacks (talk) 06:26, 29 July 2011 (UTC)

MOS also recommends using CH₃ rather than Me for methyl groups. DMacks (talk) 09:36, 29 July 2011 (UTC)

I'm not sure exactly what you mean (which is the problem describing structures using only text). I think localized single bonding/double bonding (C-C=C) is better than dotted lines or horseshoes, even though we know it's just as much C=C-C as C-C=C. The average org chem student learns single and double bonds before aromaticity or delocalization. As far as where to put the bonds and the positive charge, I think protonated quinone with + sign is better than C=O→B with + sign, because the latter requires the introduction of a new symbol.HowardJWilk (talk) 13:56, 29 July 2011 (UTC) Where do I learn how to draw structures and post structures with Wikipedia? (I mean, I know how to draw structures with, say, ChemDraw but I don't know how to do things the wiki way.)HowardJWilk (talk) 14:03, 29 July 2011 (UTC)

What I meant by the Lewis-structures was that if we want to have the rings aromatic as in the top structures but retain the localized bonding (rather than the horseshoes), the core of the molecule would wind up with a combination of single and dative bonds to the boron (and the exact position of the + a bit fuzzy). Eew, the arrows are hard to see (but I guess the image could be enhanced), but I also hate teaching that there's such a type of bond that is different from a normal covalent one. Another alternative would be to have all the boron–oxygen bonds single, and then the formal charges can be placed specifically:

I drew that diagram in ChemDraw (wikipedia follows the ACS settings) and exported as a .png, then uploaded into wikipedia and put a special tag in this talk-page comment to display it. Help:Image tutorial has information about the wiki-specific steps. Happy to help further, let me know. DMacks (talk) 14:29, 29 July 2011 (UTC)

I posted on the image description page on meta, asking for it to be enhanced/repaired/upgraded/whatever. Lets see what happens there. --Dirk Beetstra ^{T C} 14:31, 29 July 2011 (UTC)

I see. (I mean that figuratively, because I don't actually know what "image description page on meta" means. I'm still in wiki kindergarten, sorry!) I drew the structure as per Spicer, G. S.; Strickland, J. D. H. Compounds of Curcumin and Boric acid. Part I. The structure of rosocyanin Journal of the Chemical Society (London), 1952, 4644-4650 and uploaded it to Destination filename: Rosocyanine proposal.png.HowardJWilk (talk) 01:06, 30 July 2011 (UTC)

You are missing the H is missing on the upper-right quinone oxonium. I think the the Cl^– should be moved away from that corner (maybe centered vertically) so it doesn't look like it's specifically associated with that part of the structure.

The "image description page" is what you are reading when you click on an image (the copyright and other tags, etc.). I think Beetstra actually meant "on commons" not "on meta" though...the original image we are disputing (just like your improved one) are stored on the shared commons.wikimedia site not locally on the english wikipedia site. "Meta" is yet a different wiki site that isn't related here. DMacks (talk) 03:56, 2 August 2011 (UTC)

Fixed the missing H, thanks. Not sure exactly what you propose with the chloride, but you'll see where I put it. The structure is now "rosocyanine proposal 2.png". I'm not sure how best to make a negative charge by ChemDraw. The rest of the text is Arial 12. If you stay in Arial 12 and superscript the "-", I think it's too small and inconspicuous. What I've done for both negative charges is to change the size to 14, not superscripted, type a "-", and just move it into place.HowardJWilk (talk) 03:23, 3 August 2011 (UTC)

Sorry for dropping the ball here. File:Rosocyanine proposal 2.png looks fine and I placed it in the article. There is a typographic "minus" or "en-dash" character that is longer than a hyphen, and so looks decent when superscripted. I don't know how to type it directly without knowing what kind of computer you have, but I think there's a "Show character map" menu item in ChemDraw that lets you view and click-to-select the various sorts of hyphens and dashes. En-dash is usually seen as the shorter of two dash characters near the curly-quote and "œ" characters. DMacks (talk) 06:58, 2 September 2011 (UTC)

I nominated File:Rosocyanine.png, the incorrect previous image in the article that led to this discussion, for deletion on commons (Commons:Deletion requests/File:Rosocyanine.png). Follow up there if anyone wants to see this image retained for some reason. DMacks (talk) 19:13, 11 September 2011 (UTC)

I agree to replace the old drawing withe the updated one. But with regard of the former discussion on where to place the positive charge, I would leave that as in the original drawing. As already mentioned, the reality of that charge cannot described by a positive charge attached to one specific atom. It is delocalized all over the molecule, and that's why I have included two mesomeric structures of the compound. Not even one of these structures describe it rather well, where the positive charge is located. So reality is, the charge is everywhere and nowhere exactly to be located in the molecule. As already mentioned, I also would hate teaching that. But maybe that's the best way someone understand what DELOCALISATION of a charge means in reality. Only one percent of the people you teach will understand what delocalisation means in reality. Also, using the structure from the mentioned article (Journal of the Chemical Society (London), 1952, 4644-4650) would mean to use an old description, which is not rather common today to describe a delocalized positive charge, especially in the context of colour chemisty, and how to explain the generation of colours on/in molecular formulas. --Steven69 (talk) 09:05, 12 September 2011 (UTC)