A Theoretical Study About the Electronic Cooperative Effect on Hydrocyanide Chains Using DFT Calculations and Aim Topological Parameters

Abstract

A theoretical investigation about the cooperative effect on ( HCN )n homo and ( HCN )n ⋯ HF heterochains was performed in terms of structural parameters and topological properties obtained in concordance with the protocol of Bader's atoms in molecules theory. Initially, the hydrogen bonding distances, electronic densities, and Laplacian descriptors were used to characterize small ( HCN )n and ( HCN )n ⋯ HF chains formed by n = 2–4 units of HCN . Hydrogen bond distances and distribution of charge density have revealed that the cooperative effect on ( HCN )n ⋯ HF heterochains is ruled by the polarity of the extreme hydrofluoric acid species. Furthermore, we investigated larger homo and heterochain systems formed by n = 2–8 molecules of HCN . In this insight, the drastic polarized effect caused by HF molecule which was considered very substantial at prior, in fact is seriously limited by an excessive number of HCN molecules connected to the heterochain. This leads to a stabilization of the ( N ⋯ HF ) hydrogen bonds with invariable electronic density in the range of [Formula: see text]. In this stage and henceforth, the cooperative effect is re-established with n = 4 molecules of HCN . Thereby, the electronic density of the hydrogen bonds become unaltered within the ( HCN )n ⋯ HF heterochains.

Interplay between dihydrogen and alkali–halogen bonds: Is there some covalency upon complexation of ternary systems?

“…For this discussion, a brief comment should be made with regard to the values for DE (HÁ Á ÁHANaÁ Á ÁF) and DE (HÁ Á ÁHANaÁ Á ÁCl) , which reflect the contribution of four interactions, two of them being dihydrogen bonds (HÁ Á ÁH) and the others the alkali-halogen bonds (NaÁ Á ÁF and NaÁ Á ÁCl) introduced herein. This is a typical cooperative example [60,61] and, as such, it is not possible to compute accurately the strength of each isolated interaction because one uniform energy distribution occasioned by the symmetry of the ternary complexes is rooted in their electronic structures. Such cooperative energy diffusion leads to a weakness of the interaction mainly with regard to the dihydrogen bonds in ternary systems, as discussed in this paper.…”

Theoretical aspects of binary and ternary complexes of aziridine⋯ammonia ruled by hydrogen bond strength

“…It is especially important to point out that these ΔE C values are not the essence of the hydrogen bond strengths because the energies of the IV and V complexes are uncooperative. In other words, the total energy values of −247.14216984 H and −247.14384609 H cannot be divided equally among the unsymmetrical hydrogen bonds-N···H d and N···H c of IV, as well as N···H d , N···H g , and N···H a' of V-as already reported in several studies on the formation of cluster systems [86][87][88]. The ternary complexes, IV and V, are formed by two and three hydrogen bonds, respectively, where, in addition to the predominance of the electrostatic potential [89] already quoted here, it is well-known that charge transfer is one of the most important effects in intermolecular interactions [90].…”

The interaction strength of intermolecular systems formed by NaH⋯2(HF) and NaH⋯4(HF): Hydrogen bonds, dihydrogen bonds and halogen–hydride bonds

“…Optimally, the values of À94.20 (I) and À218.05 kJ$mol À1 (II) do not reflect the stabilization profile. Thus, each one of the interactions could contribute with À23.73 (I) and À36.34 (II) kJ$mol À1 , values which do not accurately represent the energetic cooperativity [66,67]. Also, cooperativity, also known as 'non-additivity', is a parameter that indicates uniformity of the electronic distribution within the molecular structure, wherein the energy quantification can be carried out by means of certain algebraic equations, e.g., the SiteeSite Function Counterpoise (SSFC) [68]:…”