Talk:Persistent carbene

Reorganise?

Hello,

I've recently updated this page with a few new sub-sections:

• Classes of stable carbenes

• History of stable carbenes

• General methods of preparing stable carbenes

• Chemistry of stable carbenes

I was wondering if we need to have a bit of a reorganise of the sections.

1) Have a general remark as to what a persistent carbene is

2) History of stable carbenes

3) Classes of stable carbenes

4) General methods of preparing stable carbenes

5) Chemistry of stable carbenes

Also could:

• The borazine and Tomioka triplet carbene go into "Classes of stable carbenes"? i.e. subheadings of "Other nucleophic carbenes" and "Triplet state carbenes".

• "Synthesis of stable carbenes" be incorporated into the "General methods of preparing stable carbenes" heading?

• "Carbenes and carbene ligands in organometallic chemistry" be incorporated into "Chemistry of stable carbenes"? i.e under the subheading of "Carbene Complextion".

Finally, I was wondering about how people find this page. A likely search word would be "stable carbene", "NHC", "carbene ligands" etc. How do we get diverts to this page?

I'm a bit new to all this and I don't want to trample on anyones toes, so please let me know what you think!!!

I think I've figured out how to do the auto-references now, so at some point I'll try and tidy these up.

all the best

Quantockgoblin 08:46, 15 August 2006 (UTC)

• I'm fine with the reorganisation, I really like to see a more-or-less logical order (e.g. dont use things, if you havent told yet how to make them).
• Diversions, Wikipedia uses redirects. That is effectively an article that only contains the tag #REDIRECT[[Persistent carbene]] (see N-Heterocyclic Carbene), if you enter that page (like: N-Heterocyclic Carbene), you will be automatically redirect to the intended page, not the difference in URL. Sometimes these can be used as a temporary name that will get a split-off of another article (Persistent carbene was for long a redirect to Carbene, until there was enough info in carbene to warrant Persistent carbene, articles that were talking about persistent carbenes were using that link, and are now automatically on the right page) Connected to this subject are disambiguation pages, pages where a term could mean different terms (see e.g. NHC).

Happy editing --Dirk Beetstra ^{T C} 09:07, 15 August 2006 (UTC)

Thanks - if anyone else is happy with the above changes then I suggest we go with it Quantockgoblin 13:45, 15 August 2006 (UTC)

Sounds OK to me. I would say be bold. --Dirk Beetstra ^{T C} 15:40, 15 August 2006 (UTC)

Photo of a carbene?

It would be nice to have a bit of colour on this page, even if it is of a white solid in a schlenk tube! If people are still in the habit of subliming these carbenes, perhaps they could take a photo and upload it to this page?

A nice way to sublime these carbenes (when free from metals) is to place a tight fitting rubber filtration cone (the sort used for getting a good seal when using a Buchner funnel) half way up the outside of a schlenk tube and fill it with dry-ice acetone and gently heat the solid in the bottom of the schlenk tube with warm water whilst applying a vacuum. The carbene sublimes as a nice white band, perfect for a photo. I would do it but I'm no longer in the lab. Obviously just wash out the residue from the bottom of the tube and wha-la, isolated carbene.

Quantockgoblin 09:25, 15 August 2006 (UTC)

I work in Arduengo group - could get a photo of one assuming it's alright with him. —Preceding unsigned comment added by 97.67.109.101 (talk) 19:22, 17 October 2009 (UTC)

In a foreword for a special issue of Australian Journal of Chemistry a couple of years ago (here, scroll down a bit to the abstract for page 1106), Arduengo provided a picture of the original sample of the diadamantylimidazo-2-ylidene. The picture is posted on the AJC website and the Foreword is available for download without charge. Could that picture be used here? There appears to be no copyright restriction that I can see and it sure would be nice to have a picture of the originally prepared carbene. There is a designation or compound number on the vial (a DuPont notebook number???). --166.205.55.41 (talk) 14:47, 4 January 2013 (UTC)

• Basic spectroscopy would also be more than welcome V8rik (talk) 21:59, 17 October 2009 (UTC)

Stable carbenes and co-ordinating Periodic table of elements

I wanted to generate a table of elements that co-ordinate to carbenes.

To do this I've used the code found on the page for Periodic table (standard) (I hope that is alright) and edited it a bit so that it can be used updated with elements that co-ordinate to stable carbenes.

There a few problems, since I used the code from table of elements it has template colours which are:

• "poor metals" to be gray colour
• "non-metals" to be green colour

The problem is that the code is a bit misleading but will read fine when it is on the web!

your views / comments please!

Quantockgoblin 12:50, 22 August 2006 (UTC)

Wanzlick equilibrium

I'm not sure how you put a internal link into a wiki article, e.g. Wanzlick equilibrium has a wiki link near the start of this article, but is more or less covered later in the article, so it would be great to have a jump-to that section. Quantockgoblin 15:08, 22 October 2006 (UTC)

I hope this was what you wanted: I created a subheading "Wanzlick equilibrium" at a part of the article that seemed appropriate, and made the link near the top jump down to it within the same page. I was surprised that it actually worked! The link looks like this: [[Persistent carbene#Wanzlick equilibrium|Wanzlick equilibrium]] --Coppertwig 01:48, 5 February 2007 (UTC)

Disambiguation

This page had a link to the disambiguation page equilibrium. I disambiguated it to chemical equilibrium but am not sure whether that was the best choice. Feel free to modify it to point to what you feel is a more appropriate page. --Coppertwig 01:40, 5 February 2007 (UTC)

GA

This almost passes. It needs a infobox at the top though. Contact me when finished and i will review it then. Geoff Plourde (talk) 21:57, 20 February 2008 (UTC)

First, I am going to strike my prior statement as there is is no clear need for a infobox. I am reviewing this article for GA status in accordance with the current criteria. I have not contributed to this article and had never heard of the topic prior to today. I do not know the principal authors of this article.

As regards GAC 1, I find this article to be extremely well written. One area where it needs to improve is in the style. As it stands this article could difficult to understand by people with minimal chemical kwnowledge.

As regards GAC 2, sources are available. I am pleased by the large number of sources. (Reference section nearly crashed my browser). i see no room for improvement.

It is broad in its coverage (GAC 3), neutral(4), and stable (5). Images are provided in sufficient quantity.

As such this in my opinion is a good article. Geoff Plourde (talk) 00:46, 21 February 2008 (UTC)

Drawings Format

Just a point on presentation.

Is there any reason why some images are in frames and others are not? I think the article would look better if all the diagrams had the same format, in terms of frames and sizes. Also I've tried to remove some "white space" from the article as I think that looks bad too.

Also, ideally the images should be redrawn as SVG images. Quantockgoblin (talk) 11:41, 20 March 2008 (UTC)

Technical detail

This article is too technical and detailed; it seems written by a specialist for other specialists. Please remember that WP is an encyclopedia, not a chemical textbook. In style and language, it should be more like Scientific American than the Journal of the ACS. Methinks that much of the detail (e.g. short-lived mistaken theories, the chemical experiments that were used to prove or disprove technical conjectures, etc.) should be trimmed or moved to separate, more specialized articles.
Also, there seems to be to much emphasis on who precisely conjectured what and which group proved which other group's claims were wrong. It reads like there is sort of an ego war going on between those groups, is that so?
All the best, --Jorge Stolfi (talk) 14:43, 3 December 2009 (UTC)

• I have moved some of the excess detail to separate articles, furoin and Wanzlick equilibrium. --Jorge Stolfi (talk) 17:22, 3 December 2009 (UTC)

• Please consider that this article already is a specialist article (the general article is carbene), there is absolute no harm in offering technical information. There is nothing wrong with building a historic picture including the detours and dead-ends. Since when should a WP article read like Scientific American? Also if you delete content this should be reflected in an edit summary. With multiple edits it is impossible to figure out if content was deleted. The content in History of persistent carbenes has completely vanished, there is also no link from this article to the furoin article. Also, if you accuse editors of engaging in ego wars, better back this up with evidence. All recent edits should be reverted. V8rik (talk) 21:42, 3 December 2009 (UTC)

• I am sorry for any harm I did to the article, and I will try to fix as best as I can. (Having been through that several times, I understand how upsetting it can be when someone else throughly scrambles one's carefully written article.)
  But I still stand to my opinion that the tone and level of detail of the previous version was excessive for Wikipedia. The "hypothetical reader" for which this (and other organic chemistry articles) should be written is not the specialist who does research on persistent carbenes, not even a professional chemist; it is someone who has a basic knowledge organic chemistry (but is most likely not a chemist!), and happens to be interested in this topic (but not neessarily because he or she works with carbenes in the lab!).
  Those are the readers who really need Wikipedia, and the reason for Wikipedia's existence is to help them. Professional researchers and chemistry students can easily find survey articles, in technical journals and textbooks, that are more detailed, precise and authoritative than anything we will ever have in Wikipedia. (And researchers who want to write a technical-grade article should publish it in those media, as it would be mostly wasted in Wikipedia.)
  I have no objections to specialized articles in WP. It is OK to have an article on carbenes, another on persistent carbenes, another on persistent imidazole-2-ylidene carbenes, and then one on 1,3-dimesityl-imidazol-4,5-dihydro-2-ylidene. But, no matter what the topic, an article should never be written just for specialists. In particular, editors should make an effort to use plainer language than what they would use in a technical journal ("functional group" instead of "moiety", etc.). Sections should be ordered according to the likely interests of non-specialist readers (with more specialized topics at the end, and excessive detail moved to separate articles), and so forth. That is the view I have got of WP, and my main guideline when I edit any article -- even, and particularly, on topics in which I am an expert.
  On the other hand, I must clarify that when I wrote "Scientific American" I was thinking of the magazine as it was in the 1960s and 1970s, not as it is today. 8-/
  The lack of a "furoin" link was obviously an oversight and is trivially fixed. I took care not to delete any significant text; every sentence and every reference should all be still there, or in the two spin-off articles. If I deleted something important, it was either by accident or because I failed to notice some fine point when condensing apparently duplicate information.
  As for messing up the version comparisons, that unfortunately is inevitable when swapping paragraphs or sections; but it is not a valid excuse for keeping the order perpetually frozen. Every article should be organized as is best for the readers, not for the conveninece of us editors.
  Finally, my words "ego war" may have been unfortunate; but reading the article I could not avoid the impression that there was far more emphasis put on who was first at what, and who proved who was wrong, than in the discoveries themselves. All the best, --Jorge Stolfi (talk) 23:37, 3 December 2009 (UTC)

• Thanks for addressing the issues. The bottom line is that too much detail does not hurt but you can always create new and more specialized articles like you did with furoin. I believe that even professional researchers will one day come to WP for information because journals like Chemical Reviews have very serious drawbacks. V8rik (talk) 17:26, 4 December 2009 (UTC)

• • Agree with V8rik. In brief: Wikipedia has an endless scope to be expanded with more specialist articles being nested (by way of wikilinks) within more general article topics.

I can't imagine anyone but a reasonably sophisticated chemist being interested in this topic (or at least one who is doing a University degree). Anyone who isn't such a chemist can probably glean what they need for the first few lines or skip back to the more general topics e.g carbenes etc.

Anyway, where would one propose to draw the distinction about where one topic is too sophisticated and where one is not – e.g. no topic to advance beyond a high school level, or earlier? On this basis, Wikipedia could be reduced to no more that a junior school dictionary.

I see no need for artificial limits. True, I've looked articles about mathematics (not my area) and wished a more general introductory paragraph than been provided, but I had no desire to cut and burn the article back to my level of understanding.

I also thought the portion relating to the history of stable carbenes helped to show how the field had evolved, and made the article more accessible to more lay readers, but perhaps the topic has evolved sufficiently now that this header is not necessary.

Re: egos - I think the point here was not groups striving for supremacy, but rather research groups getting credit for the work they did. I would not propose to exclude mention of Einstein’s name in the discussion of Special_relativity lest people suppose that by doing so this would denigrated the works of others such as Hendrik_Lorentz in the field about that time. However, I understand that the remarks starting this heading by talk were not intended to be inflammatory, I simply add my remarks to address this and hope that this will be seen in the same light -- Quantockgoblin (talk) 03:34, 10 January 2011 (UTC)

Note the dates of the previous comments; a lot of solvent has passed under the bridge sinc e then. I wonder whether any of the editors who wrote this article are still around. (By the way, I was interested enough on this topic to spend many hours editing this and related articles, including starting the bios of the main players. But I am not a chemist! Although I loved loved chemistry in high school, fate took me through other reaction paths...) All the best, --Jorge Stolfi (talk) 05:14, 10 January 2011 (UTC)

deleted citation needed content

This content was recently deleted.

Carbenes that formally derive from imidazole-2-ylidenes by substitution of sulfur, oxygen, or other chalcogens for both α-nitrogens are expected to be unstable, as they have the potential to dissociate into an alkyne (R¹C≡CR²) and a carbon dichalcogenide (X¹=C=X²).

Stated reason: "citation needed" since 2009. People add "citation needed" tags to text items all the time often for no good reason. I respect that fellow editors feel compelled to add these tags but I feel no obligation whatsoever to rush to a library and spent effort on providing a citation especially when a statement is not controversial or when it is plainly obvious (as in this case) that the citation is the one in the next paragraph (ref 40). I also expect that content such as this piece of content remains on the page until such time that a fellow editor does add a citation be it in 2014 or 2024 or 2035. Thanks V8rik (talk) 18:23, 16 November 2014 (UTC)

Hi V8rik, seems I have irritated you once again. I will make amends in a day or two, probably just reinstating the part I took out. Thanks for the note. --Smokefoot (talk) 22:13, 16 November 2014 (UTC)

I took a second look at the removed content.

"Carbenes that formally derive from imidazole-2-ylidenes by substitution of sulfur, oxygen, or other chalcogens for both α-nitrogens are expected to be unstable, as they have the potential to dissociate into an alkyne (R¹C≡CR²) and a carbon dichalcogenide (X¹=C=X²)."

A possible decomposition pathway for aromatic N-C-X (X = O, S) substituted carbenes

It is reasonable conjecture, but just that. We dont include reasonable ideas usually. Sorry if we disagree but I would be glad to discuss further because maybe I am missing something.--Smokefoot (talk) 13:40, 18 November 2014 (UTC)

Move this article to N-Heterocyclic carbenes

NHCs are a big deal. They emerged from studies on persistent carbenes, which would be the history section of a revised article.--Smokefoot (talk) 00:41, 14 January 2020 (UTC)

GA Reassessment

Persistent carbene

The following discussion is closed. Please do not modify it. Subsequent comments should be made on the appropriate discussion page. No further edits should be made to this discussion.

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Article (edit | visual edit | history) · Article talk (edit | history) · Watch • Watch article reassessment page • GAN review not found

Result: No significant improvement, even giving the extra allotted time. Delisted. ~~ AirshipJungleman29 (talk) 22:11, 2 March 2023 (UTC)

 Because of an overload of chemistry articles at GAR, if delisting, do not close before 2 March.

Quite a lot of uncited material including

• the Molecular orbitals and persistent carbenes section and its subsections
• Diaminocarbenes have diagnostic 13C NMR chemical shift values between 230 and 270 ppm for the carbenic atom. The X-ray structure of dihydroimidazole-2-ylidene shows a N–C–N bond angle of about 106°, whilst the angle of the acyclic carbene is 121°, both greater than those seen for imidazol-2-ylidenes.
• Exposure to oxygen (a triplet diradical) converts this carbene to the corresponding benzophenone. The diphenylmethane compound is formed when it is trapped by cyclohexa-1,4-diene. As with the other carbenes, this species contains large bulky substituents, namely bromine and the trifluoromethyl groups on the phenyl rings, that shield the carbene and prevent or slow down the process of dimerization to a 1,1,2,2-tetra(phenyl)alkene. Based on computer simulations, the distance of the divalent carbon atom to its neighbors is claimed to be 138 picometers with a bond angle of 158.8°. The planes of the phenyl groups are almost at right angles to each other (the dihedral angle being 85.7°).
• The Mesoionic carbenes section

and many more. These will need to be cited. Onegreatjoke (talk) 22:12, 9 February 2023 (UTC)

The discussion above is closed. Please do not modify it. Subsequent comments should be made on the appropriate discussion page. No further edits should be made to this discussion.