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

Abstract

B3LYP calculations, ChelpG atomic charges, and quantum theory of atoms in molecules (QTAIM) integrations were used to investigate the binary (1:1) and ternary (1:2) hydrogen-bonded complexes formed by aziridine (1) and ammonia (2). In a series of analysis, geometry data, electronic parameters, vibrational oscillators, and topological descriptors were used to evaluate hydrogen bond strength, and additionally to determine the more prominent molecular deformations upon the formation of C(2)H(5)N···NH(3) (1:1) and C(2)H(5)N···2NH(3) (1:2) systems. Taking a spectroscopic viewpoint, results obtained from analysis of the harmonic infrared spectrum were examined. From these, new vibrational modes and red- and blue-shifts related to the stretch frequencies of either donors or acceptors of protons were identified. Furthermore, the molecular topology of the electronic density modeled in accord with QTAIM was absolutely critical in defining bond critical points (BCP) and ring critical points (RCP) on the heterocyclic structures. Taking all the results together allowed us to identify and characterize all the N···H hydrogen bonds, as well as the strain ring of the aziridine and its stability.

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

“…Nevertheless, it is not mandatory that intermolecular complexes are formed via only one hydrogen bond [14]. Bifurcate hydrogen bonds or even those possessing multiple sites with donors (Lewis acid) and acceptors (lone-electron pairs or p clouds) of protons can lead to the formation of ternary systems [15][16][17][18][19], whose stability is arguably improved. In this context, the aim of this study was to investigate the formation of ternary dihydrogen-bonded complexes [20], such as NaHÁ Á Á2(HCF 3 ) and NaHÁ Á Á2(HCCl 3 ), and a comparative analysis of their properties with those obtained for the binary complexes NaHÁ Á ÁHCF 3 and NaHÁ Á ÁHCCl 3 [13] was carried out.…”

Quantum chemical studies of non-covalent interactions between the ethyl cation and rare gases

“…1 In conformity with these assertions, but in view of the applicability in investigations of chemical bonds and interatomic distances [63,64], the interaction distance at the B3LYP/6-311 + +G(d,p) of I is shorter than the values reported by Goswani and Arunan [65] regarding the H 2 OÁÁÁ2Ar and H 2 SÁÁÁ2Ar complexes at the MP2(full)/aug-cc-pVTZ level of theory. Absolutely, this is not enough to discriminate the efficiency between these levels of theory, but otherwise it also serves to show that ternary structures have not necessarily shorter intermolecular distances and higher interaction energies compared with binary ones [21,27,66,67]. In addition to HÁÁÁRG, the values of the bond lengths of both CÁÁÁH and p are also depicted in Fig.…”

Bent's Rule Contextualizes Hydrogen Bond Strength in Trimolecular Clusters

“…46 Outrossim, é de suma importância saber se a presença de um heterocomponente pode afetar a distribuição de energia e, principalmente, como os perfis das forças das ligações de hidrogênio variam nestas condições. Em estudos de ligação de hidrogênio, a análise vibracional harmô-nica na região de infravermelho é vital, tanto na elucidação dos novos modos vibracionais ou frequências de estiramento intermolecular 60,61 como na determinação dos efeitos batocrômicos (red-shift) 13,15,16,62 ou hipsocrômicos (blue-shift) 42,54,55,63 com alterações nas intensidades de absorção das espécies doadoras de prótons. 64 Mesmo que as variações para o vermelho e para o azul já tenham sido identificadas experimentalmente, 65 a análise vibracional harmônica certifica se o sistema intermolecular está devidamente caracterizado em uma região de mínimo global na superfície de energia potencial, e isto pode ser evidenciado pela estabilização e força de interação.…”