Comments on: (anti)aromaticity avoided: a tutorial example

By: The mechanism of the Birch reduction. Sequel to benzene reduction. « Henry Rzepa

Wed, 05 Dec 2012 11:36:44 +0000

[...] the outcome of the reduction of benzene by electrons. It also links into what happens when anti-aromaticity is avoided (when a 4n π-electron system distorts to avoid it). Share [...]

By: Joining up the pieces. Peroxidation of ethyne. « Henry Rzepa

Joining up the pieces. Peroxidation of ethyne. « Henry Rzepa — Mon, 09 Jul 2012 19:58:23 +0000

[...] I had noted that antiaromaticity in cyclopropenium anion is lessened by the system adopting gross geometric distortions, which take the anionic lone pair out of conjugation from the ring. [...]

By: The direct approach is not always the best: ethene + dichlorocarbene « Henry Rzepa

Tue, 12 Jun 2012 21:19:43 +0000

[...] a carbene and an alkene to form a cyclopropane is about as simple a reaction as one can get. But I discussed before how simple little molecules (cyclopropenyl anion) can hold surprises. So consider this [...]

By: Some fun with no-go areas of chemistry: cyclobutadiene. « Henry Rzepa

Some fun with no-go areas of chemistry: cyclobutadiene. « Henry Rzepa — Sun, 18 Sep 2011 10:09:05 +0000

[...] species, their anti-equivalent is avoided. I previously illustrated this (Hückel rule) with cyclopropenium anion. Now I take a look at cyclobutadiene, for which the π-system is said to be iso-electronic (where [...]

By: Less is more: the dyotropic rearrangement of ethane « Henry Rzepa

Less is more: the dyotropic rearrangement of ethane « Henry Rzepa — Sat, 11 Jun 2011 20:00:42 +0000

[...] apply the rules of aromaticity to the transition state describing the pericyclic reaction. I have previously described how (for themal, closed shell molecules), a 4n+2 electron count leads to aromaticity and a 4n count [...]