Resonance-Assisted Hydrogen Bond—Revisiting the Original Concept in the Context of Its Criticism in the Literature

Abstract

In the presented research, we address the original concept of resonance-assisted hydrogen bonding (RAHB) by means of the many-body interaction approach and electron density delocalization analysis. The investigated molecular patterns of RAHBs are open chains consisting of two to six molecules in which the intermolecular hydrogen bond stabilizes the complex. Non-RAHB counterparts are considered to be reference systems. The results show the influence of the neighbour monomers on the unsaturated chains in terms of the many-body interaction energy contribution. Exploring the relation between the energy parameters and the growing number of molecules in the chain, we give an explicit extrapolation of the interaction energy and its components in the infinite chain. Electron delocalization within chain motifs has been analysed from three different points of view: three-body delocalization between C=C-C, two-body hydrogen bond delocalization indices and also between fragments (monomers). A many-body contribution to the interaction energy as well as electron density helps to establish the assistance of resonance in the strength of hydrogen bonds upon the formation of the present molecular chains. The direct relation between interaction energy and delocalization supports the original concept, and refutes some of the criticisms of the RAHB idea.

Effect of a Substituent on the Properties of Salicylaldehyde Hydrazone Derivatives

“…The intramolecular H-bond pattern present in the system is of particular interest, as it characterizes a so-called resonance-assisted hydrogen bond, first reported by Gilli and coworkers, − and is also found in hydrazone derivatives . A thorough introduction to the RAHB topic is given by Domagała et al Because the extra-ring formed via the hydrogen bonding is a π-electron conjugated along the sequence of formally covalent bonds, it may be also classified as a quasi-aromatic ring . Both aromatic and quasi-aromatic rings are fused in this case and strongly interact with themselves, as previously observed in structurally related systems. − The interaction between the two rings happens mostly via the resonance effect, and as such, it may be effectively modulated by the substitution effect. − This paper examines the influence of the substitution of the benzene ring in positions 4 and 5 on the varied properties of salicylaldehyde hydrazones.…”

Novel melamine – salicylic salt solvates and co-crystals; an analysis of the energetic parameters of the intermolecular hydrogen bonds stabilizing the crystal structure

“…Interaction energies were estimated by means of super molecular approach. 37,38 Calculations were performed using B3LYP functional 39 in conjunction with 6-311++G(d,p) Pople's basis set. 40,41 The Gaussian 09 set of codes was implemented for calculations.…”

Revealing the Reasons for Degeneration of Resonance-Assisted Hydrogen Bond on the Aromatic Platform: Calculations of Ortho-, Meta-, Para-Disubstituted Benzenes, and (Z)-(E)-Olefins

“…Resonance-assisted hydrogen bonding (RAHB) is one of the well-established concepts of modern theoretical and structural chemistry, developed in 1989 due to the works of Gilli et al [ 1 , 2 , 3 , 4 ]. Although the RAHB concept has been disputed and revisited many times [ 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 ], it is still a valid and commonly accepted theory [ 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 ]. Nevertheless, an in-depth study of the RAHB nature remains an urgent challenge, since the presence of such a hydrogen bond affects the structure, physicochemical properties, and reactivity of molecules.…”