Is it possible to follow the change in aromaticity along the IRC path ?

Julien

Hello Dears,I'm studying a reaction in which one of the reactif has an aromatic ring. the aromatic properties disappear at the final product, and only one double bond has been kept. I performed Topological analysis of the electron localisation function (ELF) for each point of the IRC (BET) using Multiwfn program, in purpose to reveal the mechanism of the reaction, but when I plotted the basin population for the aromatic double bond, I found that there is cuts in the plot and the double bond keep disappearing and appearing (see attached image).
I don't know how to interpret this result, or my analysis is wrong.
I have an additional, question is it possible to follow the change in aromaticity along the IRC path ?


               

sobereva

I strongly suggest plotting variation of multicenter index (MCI, also known as multicenter bond order) along the IRC, you can clearly study how aromaticity changes. I have a blog article to illustrate this point: http://sobereva.com/200 (see Section 3). Some content of this article in English is also available in Section 4.A.1 of Multiwfn manual.

Julien

sobereva 发表于 2022-3-13 04:24
I strongly suggest plotting variation of multicenter index (MCI, also known as multicenter bond orde ...

Thank you very much Professor,  I will take your suggestion.
About the double bond C4=C6, the ploting of the double bond population along the IRC, shows breaking and forming of the bond multiple times, why there is such a behaviour? I couldn't interpret that.

sobereva

Julien 发表于 2022-3-13 04:58
Thank you very much Professor,  I will take your suggestion.
About the double bond C4=C6, the plo ...

I don't know, you should manually perform topology analysis for relevant IRC points, and check if shape of the corresponding basin or corresponding ELF isosurface varies smoothly among the points, and also check if basin index was correctly identified.