7‐Arylnorbornanes: Model Compounds for the Study of CH···π and OH···π Interactions

Abstract

Keywords: Conformation analysis / Molecular modeling / Noncovalent interactions / Pi interactions / Density functional calculationsPreorganised 7-arylnorbornanes were selected as suitable model compounds for the study of CH···π and OH···π interactions. The most stable conformation of these derivatives favours such interactions by avoiding secondary hydrogen bonds between the oxygen atoms and the ortho-H of the aryl rings in the planar conformation as well as by increasing the gauche/trans ratio for steric reasons. The rotational barriers of the studied compounds are higher when electron-donor substituents are placed at the para position of the aryl ring. The trend of the electronic effects exerted by the substituents

Predicting OH stretching fundamental wavenumbers of alcohols for conformational assignment: different correction patterns for density functional and wave-function-based methods

“…Included in the training set are b,gunsaturated alcohols (e.g., phenylmethanol), as the classification of their very weak OHÁ Á Áp interaction is disputed. [51][52][53][54] The derived model from and for transitions of non-hydrogen-bonded conformers is later tested for its performance for hydrogen-bonded species.…”

σ-Hole⋯π and lone pair⋯π interactions in benzylic halides

“…1). [37][38][39][40][41] Crystal structures Most of the studies on halogen⋯π bonds carried out until now are based on intermolecular interactions where the interacting subunits can adopt a T-shaped arrangement with the σ-hole of the halogen atom pointing directly towards the π electrons of the donor moiety.…”

“…7). 37,39 When X or Y are halogen atoms heavier than Cl, the rotational barriers are too high to be determined (T c > 150°) due to steric hindrance. 37,39 The rotational barriers can be easily measured by D-NMR introducing substituents (Y) in the ortho position of the phenyl ring and by analyzing the coalescence of the bridgehead protons.…”

“…Preorganized 7-arylnorbornanes have been successfully used to study aromatic faceto-face and edge-to-face interactions, C-H⋯π and O-H⋯π interactions, as well as in the design of stable supramolecular complexes with Ag + and NH 4 + ions. [37][38][39][40][41] Crystal structures…”

“…An important advantage of this type of compounds is that the rotational barriers of the phenyl rings provide valuable information about the energies and the non-covalent interactions present in these species. 37,39 The rotational barriers can be easily measured by D-NMR introducing substituents (Y) in the ortho position of the phenyl ring and by analyzing the coalescence of the bridgehead protons. The values of these rotational barriers represent the energy difference between the most stable perpendicular conformation a and the planar conformation in the corresponding transition state, TS (ΔE rot in Fig.…”