Ab initio study of substituent effects in the interactions of dimethyl ether with aromatic rings

Abstract

Ab initio calculations have been used to investigate the interaction energies of dimers of dimethyl ether with benzene, hexafluorobenzene, and several monosubstituted benzenes. The potential energy curves were explored at the MP2/aug-cc-pVDZ level for two basic configurations of the dimers, one in which the oxygen atom of the dimethyl ether was pointed towards the aromatic ring and the other in which the oxygen atom was pointed away from the aromatic ring. Once the optimum intermolecular distances between the dimethyl and the aromatic ring had been determined for each of the dimers in both configurations at the MP2/aug-cc-pVDZ level, single point energy calculations were performed at the MP2/aug-cc-pVTZ level. A CCSD(T) correction term to the energy was determined and this was combined with the MP2/aug-cc-pVTZ energies to estimate the CCSD(T)/aug-cc-pVTZ interaction energies of the dimers. The estimated CCSD(T)/aug-cc-pVTZ interaction energies are predicted to be attractive for all of the dimers in both configurations and dispersion interactions are found to be a large component of the stabilization of the dimers. For the dimers with the dimethyl ether oxygen pointing towards the aromatic ring, the strengths of interaction energies are found to increase as the aromatic ring becomes more electron deficient, while for the dimers with the dimethyl ether oxygen pointing away from the aromatic ring, they increase as the aromatic ring becomes more electron rich. In both cases, the trends can be explained in terms of the electrostatic potentials of the dimethyl ether and the aromatic rings.

Exploiting non-covalent π interactions for catalyst design

“…Like the anion–π interaction, it is typically expected to be more important for electron-deficient π-systems, and can qualitatively be understood as the interaction between regions of negative (the lone pair) and positive (the Q zz component of the traceless quadrupole moment tensor above and below the face of the π system) electrostatic potential 81,82 . However, several studies, both theoretical 83–85 and experimental, have noted the shortcomings of this picture and acknowledge the likely significance of electron correlation, or dispersion effects, with weak attractive interactions having been observed for electron-rich aromatic systems with negative quadrupole moments 86 . Although it is expected to be individually quite weak, the significance of the lp–π interaction has been noted in cooperation with other NCIs such as hydrogen-bonding (see below) 87,88 .…”

Aromatische Ringe in chemischer und biologischer Erkennung: Energien und Strukturen

“…Substituenteneffekte (X = CN, F, H, Me, NH 2 , NMe 2 ) auf C 6 H 5 X-C 6 F 6 -Komplexe wurden bis zum MPs(voll)/aug-cc-pVDZ-Theorieniveau berechnet. [133] Parallel verschobene Dimergeometrien zeigten sich dabei als stabiler als Face-to-Face-Geometrien. […”

“…[254] Andere Übersichtsartikel behandeln Übergangsmetallkation-p-Wechselwirkungen in der Gasphase [255] und Kation-p-Wechselwirkungen von Metallionen, die an aromatische Liganden koordinieren. [256] Die Bindung von Cs + an p-Sulfonatocalix [4]aren wurde mithilfe von 133 Cs-Diffusions-NMR-Spektroskopie [257] untersucht, wobei eine Bindungsaffinität von K a = (22 AE 9) m À1 in wässriger Lösung ermittelt wurde, in guter Übereinstimmung mit Werten von 1 H-NMR-spektroskopischen Titrationen [257] und mikrokalorimetrischen Techniken. [258] Mikrokalorimetrische Studien der Bindung verschiedener Metallionen an p-Sulfonatocalix [4]aren in Wasser zeigten, dass Na + und Ag + keine Komplexe mit dem Wirt in Wasser bilden, im Unterschied zu K + , Rb + und Cs + .…”

Lone pair···π interactions involving an aromatic π-system: Complexes of hexafluorobenzene with dimethyl ether and trimethylamine

“…Even though the complexes between C 6 F 6 and different Lewis bases have been described theoretically [20,21], experimental results supporting these findings, apart from the complex formed with water, are still scarce [22]. In this study the complexes between C 6 F 6 and dimethyl ether (DME) and trimethylamine (TMA) have been evaluated at equilibrium conditions using FTIR spectroscopy of liquid noble gas solutions.…”