Through-space interactions between parallel-offset arenes at the van der Waals distance: 1,8-diarylbiphenylene syntheses, structure and QM computations

Abstract

A model for studying polar-pi interactions between arenes spaced at van der Waals distances is developed on the basis of peri-diarylbiphenylenes. A set of 1,8-diarylbiphenylenes is synthesized comprising two Hammett series, one with reference to mesityl ring interactions and the other with reference to pentafluorophenyl ring interactions. X-Ray crystal structures of several derivatives are determined. Barriers to rotation of the probe aryl ring are derived from dynamic NMR data and show a trend for the mesityl reference series (DeltaG(not equal) vs. sigma(0)). The model is also used as a test for comparison of modern density functional methods, including B3LYP, M06-2X and BMK functionals; dispersive effects are seen to be an important factor in the proper theoretical treatment of arene interactions.

Sterische Hinderung kann ein labiles Molekül stabilisieren: zur Lösung des Hexaphenylethan‐Rätsels

“…[8] Die elektronischen Effekte der tert-Butylgruppen kçnnen angesichts ihrer großen Entfernung zur zentralen C-C-Bindung als klein angenom-men werden. Darüber hinaus sollten solche Effekte, falls sie überhaupt existieren, die radikalischen Dissoziationsprodukte mit Elektronenmangelcharakter stabilisieren; in 3, welches ebenfalls in persistente Radikale dissoziiert, [5] tut sie dies nur geringfügig.…”

Localized orbital corrections applied to thermochemical errors in density functional theory: The role of basis set and application to molecular reactions

“…1, as compared to other widely used functionals͒, we also investigate the performance of the M05-2X functional of Zhao et al, 9 both in its native form and incorporating LOCs. We have selected M05-2X for investigation because it has displayed interesting abilities to achieve reasonable results for properties that other DFT methods have great difficulty with ͑e.g., dispersion interactions͒, [10][11][12] while at the same time preserving respectable results for the traditional atomization energy benchmarks ͑the M06-2X functional 13 has similar advantages 11,12,[14][15][16] ͒ and is the most recent version of this family of functionals; its limited analysis is also carried out in this work͒. Furthermore, M05-2X has previously been benchmarked on only a subset of the G3 molecules; evaluation of results for the complete G3 set provides a fuller picture of its performance.…”

CH–π and π–π Interactions as Contributors to the Guest Binding in Reversible Inclusion and Encapsulation Complexes

“…The importance of the electrostatic contribution in the "face-to-face" stacking geometry has been clearly demonstrated by Cozzi and Siegel in a series of studies [10,11]. The relative importance of electrostatic forces with respect to polarisability and van der Waals interactions in the "edge-to-face" [12] and "offset-stacked" [13,14] geometries have also been assessed recently. These two types of geometries are the most abundant in Nature and supramolecular chemistry.…”