13
$\begingroup$

There are some non-classical carbocations, such as the 2-norbornyl cation, in which the positive charge is heavily delocalised. Have non-classical carbanions also been discovered? I have not seen any non-classical carbanions in books. If there are any non-classical carbanions, please provide some examples.

$\endgroup$
  • $\begingroup$ If an answer has helped solve your question, please consider upvoting and/or accepting one (by clicking on the tick next to the voting buttons). That's the Stack Exchange way of saying thank you! See also: chemistry.stackexchange.com/help/someone-answers $\endgroup$ – orthocresol Dec 24 '18 at 2:26
9
$\begingroup$

In addition to the species mentioned in the answer above, I found another one in Organic Chemistry by Morrison and Boyd(Seventh Edition)enter image description here

$\endgroup$
17
$\begingroup$

Interesting question. It is much less studied and reported on than the case of non-classical carbocations, but I did find a few papers. Brown and Occolowitz (Brown, J. M.; Occolowitz, J. L. Chem. Commun. 1965, 376–377) reported that deuterated bicyclo[3.2.1]octa-2,6-diene 1b, below, undergoes base-catalysed de-deuteration (potassium tert-butoxide in DMSO) to give 1a much faster (ca. 3 x 10^4) than the bicyclo[3.2.1]octa-2-ene counterpart, ie. 2b -> 2a. They suggested this is evidence for the intermediacy of a 6π-electron, delocalised (non-classical) carbanion 3.

enter image description here

Much more recently, Brown reviewed and provided additional DFT computational evidence for stabilisation and charge delocalisation in these species (Brown, J. M. Aust. J. Chem. 2014, 67, 1296–1300).

$\endgroup$

Your Answer

By clicking "Post Your Answer", you acknowledge that you have read our updated terms of service, privacy policy and cookie policy, and that your continued use of the website is subject to these policies.

Not the answer you're looking for? Browse other questions tagged or ask your own question.