By comparison, the endo-isomer ionizes to a classical 2º-carbocation, which is rapidly converted to the more stable nonclassical ion. Cations of this sort have been referred to as non-classical ions. The energy difference between “classical” carbocations and. “Non – Classical” Carbocations used to describe carbocations stabilized by 3- center, 2e. – interactions ex: 1. 2. 3 question: what is the structure of the cation?.
|Published (Last):||15 May 2005|
|PDF File Size:||15.42 Mb|
|ePub File Size:||8.74 Mb|
|Price:||Free* [*Free Regsitration Required]|
SE but there seems to be nothing for carboations level of understanding on the Internet! Here is a picture of a “classical” carbocation, there is an electron deficient carbon bearing a positive charge.
Carbocations – Chemistry LibreTexts
There are many examples of “non-classical” carbocations, but the 2-norbornyl carbocation is among the best known. Labeling experiments have shown that the positive charge resides on more than one carbon in the 2-norbornyl ion. Early on, the data was explained by equilibrating classical ions, but soon another possibility emerged – one involving a single non-classical ion. The problem comes down to: Acrbocations debate went on for a very long period carbbocations time, but now most agree that the non-classical structure is the ground state in the 2-norbornyl system.
In fact, a recent, and difficult to obtain, crystal structure for the 2-norbornyl cation has been published proving that the ion exists with the non-classical geometry thanks to Klaus for finding this reference, see his comment vlassical.
A nonclassjcal difference between classical and non-classical structures is the bonding. As illustrated above, a classical ion has a carbon with a sextet of electrons and 3 other bonds.
The non-classical ion, on the other hand, involves 3 carbons with 2 electrons spread over them. This is called a 3-center 2-electron bond hypercoordinate bonding and is a clear marker for a non-classical ion. Notice nonclasxical you count all of the bonds to any of these 3 carbon atoms solid and dashed lines you count 5!
Home Questions Tags Users Unanswered. What is a non-classical carbocation?