Quantification of Noncovalent Interactions in Azide–Pnictogen, –Chalcogen, and –Halogen Contacts

Abstract

The noncovalent interactions between azides and oxygen‐containing moieties are investigated through a computational study based on experimental findings. The targeted synthesis of organic compounds with close intramolecular azide–oxygen contacts yielded six new representatives, for which X‐ray structures were determined. Two of those compounds were investigated with respect to their potential conformations in the gas phase and a possible significantly shorter azide–oxygen contact. Furthermore, a set of 44 high‐quality, gas‐phase computational model systems with intermolecular azide–pnictogen (N, P, As, Sb), –chalcogen (O, S, Se, Te), and –halogen (F, Cl, Br, I) contacts are compiled and investigated through semiempirical quantum mechanical methods, density functional approximations, and wave function theory. A local energy decomposition (LED) analysis is applied to study the nature of the noncovalent interaction. The special role of electrostatic and London dispersion interactions is discussed in detail. London dispersion is identified as a dominant factor of the azide–donor interaction with mean London dispersion energy‐interaction energy ratios of 1.3. Electrostatic contributions enhance the azide–donor coordination motif. The association energies range from −1.00 to −5.5 kcal mol−1.

Azide⋅⋅⋅Oxygen Interaction: A Crystal Engineering Tool for Conformational Locking

“…The bond dissociation energy of these interactions from the Espinosa correlation [26] is calculated to be between 2.38 kcal mol −1 to 4.17 kcal mol −1 . The closed‐shell nature and energetics agree well with the previous studies, that this interaction arise mainly due to London dispersion and electrostatic forces between azide‐donor pairs [13] …”

“…Apart from the common and well‐studied NCIs such as various types of hydrogen bonding, [7] halogen bonding, [8] chalcogen bonding, π‐π stacking, dipole‐dipole interaction, [9] several other interactions have come to light recently [10, 11] . Our recent study on azide‐chalcogen interaction suggested that it involves both London dispersion interactions [12] and electrostatic contributions [13] . However, for any new NCI to be used for designs with confidence, experimental validation of its influence and relevance in different molecular systems is essential.…”

Automated exploration of the low-energy chemical space with fast quantum chemical methods

“…In conclusion, CREST is a powerful tool for simulations of molecules up to a few hundred atoms and will potentially find wide spread application in computational chemistry. Since first being published, the program has already been applied for a diverse number of projects, e.g., the large scale conformer generation of organometallic compounds, 183,590 protein side chain conformational sampling, 591 gas docking in metal-organic frameworks (MOF), 444 input generation of machine-learning approaches, 414 and various other mechanistic, 592-594 conceptual, [595][596][597][598] and spectroscopic studies. 22,476,[599][600][601] In Part III, a recent extension to the CREST code was presented and discussed linking the conformational low-energy chemical space to statistical thermodynamics.…”

Azide⋅⋅⋅Oxygen Interaction: A Crystal Engineering Tool for Conformational Locking

“…[26] Theb ond dissociation energy of these interactions from the Espinosa correlation [26] is calculated to be between 2.38 kcal mol À1 to 4.17 kcal mol À1 .T he closed-shell nature and energetics agree well with the previous studies, that this interaction arise mainly due to London dispersion and electrostatic forces between azide-donor pairs. [13] Topological analysis for this particular interaction has been quite challenging because of certain abnormal trends. Forinstance,weobserved that structure 33 (Figure S2), which did not show BCP in its crystal structure geometry,shows an azide-oxygen interaction in its geometry-optimized structure.…”

“…[10,11] Our recent study on azide-chalcogen interaction suggested that it involves both London dispersion interactions [12] and electrostatic contributions. [13] However,f or any new NCI to be used for designs with confidence,e xperimental validation of its influence and relevance in different molecular systems is essential. Here we report the experimental proof for the role of azide•••oxygen interaction in dictating the conformation of different classes of molecules.…”