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saeed_E

Member

Registered: 2019-12-21

Posts: 292

An unexplainable observation in the EDA

Dear Tian,

Please, if possible, let me respectfully ask you a question regarding some unexplainable results in EDA I have recently encountered.

Please suppose 1,3-Aza Diene (A), including a sp2 hybridized nitrogen atom in position 2, interacts with some Lewis acids leading to inter-molecular tetrel-, pnictogen-, chalcogen-, and halogen-bound complexes (these LAs are SnH3F, SbH2F, TeHF, and FI all include a sigma-hole in the extension of heavy atom-F bond). These complexes participate in an Aza-Diles-Alder reaction toward a given dienophile (let's to be acetylene).

My energy decomposition energy analysis (EDA) indicates that electrostatic interaction is the main predominant player in stabilizing complexes considered. To explore the origin of the electrostatic interaction predominance, I calculated the atomic charge (Hirshfeld, NPA, VDD) on the heavy atoms of LAs. Unfortunately, computed atomic charges are not consistent with the values of electrostatic interactions. Indeed, while the positive charge on the heavy atoms of LAs decreases (becomes less positive) the electrostatic interaction between heavy atoms in LAs and nitrogen of Aza Diene increases (becomes more negative or stabilizing).
If possible, please let me know how you explain this strange and inconsistent observation.

In advance, please accept my highest gratitude for your kind attention to guiding me with your professional and golden comments and, please excuse me for bothering you.

Sincerely yours,
Saeed

Last edited by saeed_E (2025-03-14 02:06:28)

sobereva

Tian Lu (Multiwfn developer)

From: Beijing

Registered: 2017-09-11

Posts: 1,954

Website

Re: An unexplainable observation in the EDA

If sigma-hole acts as the Lewis-acid in the electrostatic interactions, atomic charge is useless, because it is unable to reflect strength of sigma-hole. Using the ESP maximum value at the sigma-hole position derived by Multiwfn to discuss is much more useful.

saeed_E

Member

Registered: 2019-12-21

Posts: 292

Re: An unexplainable observation in the EDA

Dear Tian,
Many thanks for your highly valuable and informative comments.
Interestingly, as you have nicely recommended, the value of electrostatic interactions is quite consistent with the value of V_s,max calculated for heavy atoms in LAs.

Sincerely,
Saeed