Fully Zwitterionic Diaminobenzoquinonediimines Promoted by Cyanoaromatic N-substituents

Tereza Horáčková (1, 2) , Manon H.E. Bousquet (3) , Adrien Morice (3) , Ugo Triballier (3) , Gabriel Canard (1) , Pavel Lhoták (2) , Denis Jacquemin (3) , Simon Pascal (1) , Olivier Siri (1)

1 CINaM - Centre Interdisciplinaire de Nanoscience de Marseille
2 UCT Prague - University of Chemistry and Technology Prague
3 CEISAM - Chimie Et Interdisciplinarité : Synthèse, Analyse, Modélisation

2,5-Diamino-1,4-benzoquinonediimine (DABQDI) derivatives possessing two electron-withdrawing aromatic N-substituents can potentially exhibit a zwitterionic ground state in lieu of the expected canonical structure. It was previously shown that the use of nitroaromatics electron-withdrawing groups (EWG) could yield the quantitative formation of zwitterionic tautomer of DABQDI in polar solvents, while a mixture of canonical and zwitterionic forms was present in low polarity solvents. In this work, we report that the replacement of nitro-containing EWG by weaker nitrile ones prevents the formation of canonical species in apolar solvents for the benefit of the zwitterionic tautomer. This counterintuitive observation is rationalized with theoretical calculations, which points out that the fully zwitterionic electronic structure of the nitrile-containing DABQDI arises from the absence of possible intramolecular hydrogen bonding between the cyanoaromatic N-substituent and the N–H proton of the bridge in the canonical form

Domaines: Chimie organique; Chimie théorique et/ou physique

Tereza Horáčková, Manon H.E. Bousquet, Adrien Morice, Ugo Triballier, Gabriel Canard, et al.. Fully Zwitterionic Diaminobenzoquinonediimines Promoted by Cyanoaromatic N-substituents. Dyes and Pigments, In press, ⟨10.1016/j.dyepig.2022.110681⟩. ⟨hal-03758293⟩