Role of substituents on resonance assisted hydrogen bonding vs. intermolecular hydrogen bonding

• Published in: CrystEngComm Vol. 22; no. 4; pp. 628 - 633
• Main Authors: Gurbanov, Atash V., Kuznetsov, Maxim L., Demukhamedova, Svetlana D., Alieva, Irada N., Godjaev, Niftali M., Zubkov, Fedor I., Mahmudov, Kamran T., Pombeiro, Armando J. L.
• Format: Journal Article
• Language: English
• Published: Cambridge Royal Society of Chemistry 2020
• Subjects: Bonding strength; Chemical bonds; Crystallography; Functional groups; Hydrogen; Hydrogen bonding; Methylene; NMR; Nuclear magnetic resonance; Resonance
• ISSN: 1466-8033; 1466-8033
• DOI: 10.1039/C9CE01744E

The role of substituents on resonance assisted hydrogen bonding (RAHB) vs. intermolecular hydrogen bonding is highlighted in known arylhydrazones of active methylene compounds (AHAMCs) and in their new representatives – ( E / Z )-2-(2-( para -substitutedphenyl)hydrazineylidene)- N , N -diethyl-3-oxobutanamides (–C 2 H 5 , –H, –COOH, –CN). The strength of the H-bond depends on the attached functional groups to both the active methylene fragment and the aromatic moiety of the AHAMC. For instance, attachment of the strong electron donor group –N(C 2 H 5 ) 2 ( σ p = −0.72) to the active methylene fragment of AHAMC allows to isolate this class of compounds without RAHB but with strong intermolecular H-bonds, which are the first examples reported herein.