Two series of conformation ally restricted polycyclic compounds (1-3 and 4-7) have been synthesized as model systems for studying the through-space interactions between face-to-face, center-to-edge (parallel-offset) oriented arenes. These compounds feature different X substituents on one of the interacting rings. By monitoring the variation of the DeltaG(not equal) for the rotation around the aryl-aryl bond in 1-7 as a function of X by 2D [H-1,H-1] EXSY NMR spectroscopy, it was found that the barriers increase on passing from electron-donating to electron-withdrawing substituted derivatives. Quantum mechanical calculations [MP2/DVZ (2d,p)//B3LYP/DVZ(2d,p)] gave barrier values and variations in agreement with the experimental data. The results are consistent with a repulsive arene-arene interaction dominated by electrostatic effects.
|Titolo:||Through-space interactions between face-to-face, center-to-edge oriented arenes: importance of polar-pi effects|
COZZI, FRANCO (Primo)
ANNUNZIATA, RITA MARIA (Secondo)
|Settore Scientifico Disciplinare:||Settore CHIM/06 - Chimica Organica|
|Data di pubblicazione:||2003|
|Digital Object Identifier (DOI):||10.1039/b208871a|
|Appare nelle tipologie:||01 - Articolo su periodico|