Computational evidence for back donation in an N → O group based on modes of transmission of substituent effects in 3-(4′-substituted) phenylfuroxans

Kód výsledku v IS VaVaI

RIV/61388963:_____/21:00541397 - isvavai.cz

Výsledek na webu

https://doi.org/10.1007/s12039-021-01885-7

DOI - Digital Object Identifier

10.1007/s12039-021-01885-7

Jazyk výsledku

angličtina

Název v původním jazyce

Computational evidence for back donation in an N → O group based on modes of transmission of substituent effects in 3-(4′-substituted) phenylfuroxans

Popis výsledku v původním jazyce

The N-oxide nitrogen in C-4′ substituted 3-phenyl furoxans occupies a position analogous to C-β in 4-substituted styrenes that have been examined for modes of transmission of substituent effects from the C-4 substituent to C-β. From geometry optimizations through high-level MO theory calculations, it was first ensured that the N-2–C-3 liaison in 3-(4′-substituted)phenyl furoxans retains as much double-bond character as it does in the case of furoxan bearing no substituents and that the para-substituted phenyl and furoxan rings maintain near uniplanarity. The calculations, carried out for such furoxans, chosen to represent a spectrum of effects from electron-donor to electron-acceptor, showed how the change in the 4′-substituent affects electron redistribution within N-oxide group in the way expected: while the residual positive charge at N increases the residual negative charge at O decreases. An increase in the N-oxide bond order (as measured by the Wiberg bond index), together with a small reduction in the N-2–O-6 bond length, was also found. That these effects were not artefacts of the calculation procedure was ensured when the calculations, repeated using a different functional, showed not only inverse dependence of positive N-2 and negative O-6 net charges on N-2–O-6 bond lengths but also confirmatory evidence from N-oxide bond dissociation and second-order perturbation energies. These results are interpreted as demonstrating graded back donation from O to N within the N → O group caused by a combined action of mesomerism and π-polarisation involving the substituent at the para-position of the phenyl group offering a spectrum of effects from electron-releasing to electron-withdrawing. Graphical abstract: Calculations at the B3LYP/6-31++G** level have shown that back donation from O to N in N → O in 3-(4′-X-phenyl) furoxans increase with a change of X from electron-donor to electron-acceptor.

Název v anglickém jazyce

Computational evidence for back donation in an N → O group based on modes of transmission of substituent effects in 3-(4′-substituted) phenylfuroxans

Popis výsledku anglicky

The N-oxide nitrogen in C-4′ substituted 3-phenyl furoxans occupies a position analogous to C-β in 4-substituted styrenes that have been examined for modes of transmission of substituent effects from the C-4 substituent to C-β. From geometry optimizations through high-level MO theory calculations, it was first ensured that the N-2–C-3 liaison in 3-(4′-substituted)phenyl furoxans retains as much double-bond character as it does in the case of furoxan bearing no substituents and that the para-substituted phenyl and furoxan rings maintain near uniplanarity. The calculations, carried out for such furoxans, chosen to represent a spectrum of effects from electron-donor to electron-acceptor, showed how the change in the 4′-substituent affects electron redistribution within N-oxide group in the way expected: while the residual positive charge at N increases the residual negative charge at O decreases. An increase in the N-oxide bond order (as measured by the Wiberg bond index), together with a small reduction in the N-2–O-6 bond length, was also found. That these effects were not artefacts of the calculation procedure was ensured when the calculations, repeated using a different functional, showed not only inverse dependence of positive N-2 and negative O-6 net charges on N-2–O-6 bond lengths but also confirmatory evidence from N-oxide bond dissociation and second-order perturbation energies. These results are interpreted as demonstrating graded back donation from O to N within the N → O group caused by a combined action of mesomerism and π-polarisation involving the substituent at the para-position of the phenyl group offering a spectrum of effects from electron-releasing to electron-withdrawing. Graphical abstract: Calculations at the B3LYP/6-31++G** level have shown that back donation from O to N in N → O in 3-(4′-X-phenyl) furoxans increase with a change of X from electron-donor to electron-acceptor.

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

10403 - Physical chemistry

Projekt

—

Návaznosti

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Rok uplatnění

2021

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název periodika

Journal of chemical sciences

ISSN

0974-3626

e-ISSN

0973-7103

Svazek periodika

133

Číslo periodika v rámci svazku

1

Stát vydavatele periodika

IN - Indická republika

Počet stran výsledku

7

Strana od-do

31

Kód UT WoS článku

000629533200002

EID výsledku v databázi Scopus

2-s2.0-85102558278