Hydrogen bonds between hydrogen fluoride and aromatic azines: An ab initio study

Abstract

p) ab initio molecular orbital calculations have been employed to characterize hydrogen-bonded complexes between hydrogen fluoride as proton donor and aromatic azines (pyridine, pyrimidine, pyridazine, pyrazine, 1,3,5-triazine, and 1,2,4-triazine). Our calculations have shown that the H-bond strength in these complexes depends on both the number of nitrogen atoms as well as the position of these atoms in aromatic ring. The binding energies of azines-HF with or without BSSE and ZPE corrections decrease with the increasing number of nitrogen atoms in the ring. For example, its ⌬E BSSE,ZPE value is 40.9 kJ ⅐ mol Ϫ1 in pyridine-HF, whereas its corresponding values in pyrazine-HF and 1,3,5-triazine-HF are 34.0 kJ ⅐ mol Ϫ1 and 26.6 kJ ⅐ mol Ϫ1 , respectively. With respect to position of the nitrogen atom in the aromatic ring, the more pronounced effect is verified when it is at meta-position relative to the pyridine ring. There is a high linear correlation between the H-bond strength in these complexes and the intermolecular charge transfer using corrected Mulliken charges obtained from the charge-charge flux-overlap (CCFO) modified model for infrared intensities. Finally, our MP2/6-31ϩϩG(d,p) calculations have revealed that stronger hydrogen bonds are associated with smaller H-bond length values, larger intermolecular charge transfers and greater HOF downward stretching frequency displacements.

Structure, energy, vibrational spectrum, and Bader's analysis of π⋯H hydrogen bonds and H−δ⋯H+δdihydrogen bonds

“…In comparison with the observations described by Solimannejad and Alkorta 321 regarding the spectrum shifting and charge transference amounts of dihydrogen-bonded complexes, it can also be observed that the high values of Q (O) accord well with large displacements and vice-versa. In spite of this, similar results were obtained for p hydrogen bonded complexes formed by acetylene and monoprotic acids, 273,274 albeit with the application of the Charge-Charge Flux-Overlap (CCFO) 537,[747][748][749][750] to compute the corrected charges. 751 Dn Str H-X = 7324.4[DQ (O) , H-X] + 61.1, R 2 = 0.99 (14) At this current time, the QTAIM theory is considered one of the most used computational schemes in studies of electronic structure [752][753][754][755] because the positive values of the Laplacians of r (r 2 r) accompanied by low quantities of electron density bring the ideal information to characterize the chemical bond, in particular its strength and shape.…”

Tuning the metal–ligand bond in theσ‐complexes of stannylenes and azabenzenes

“…This trend is also shared among various kinds of intermolecular interactions involving aromatic diazines. It is known that 5 forms stronger hydrogen, halogen and chalcogen bonding interactions than 2 and 4 94–96 . The strength of the interaction between a – l and 5 is in fact even higher than in the corresponding pyridine complexes ( 1a – l ).…”

“…It is known that 5 forms stronger hydrogen, halogen and chalcogen bonding interactions than 2 and 4. [94][95][96] The strength of the interaction between a-l and 5 is in fact even higher than in the corresponding pyridine complexes (1a-l). The strong interaction between the moieties of 5a-l is associated with a compression in the Sn N bond length.…”

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

“…A vibrational analysis of complexes I-V was carried out to examine the new vibrational modes commonly known as hydrogen bond stretch frequencies, as well as the main alterations in the stretch modes of the proton donors [91], the nature of which may be red-or blue-shift. According to the values summarized in Table 3 there is no conflict because the hydrogen bond N···H c is not preferential in IV as the protonation on the aziridine can occur on nitrogen.…”