Internal rotation in 1,2-di-(p-XC6H4)ethanes (X = H, Br, NO2): Infrared spectra and compensation effect

Abstract

Infrared absorption spectra and internal rotation of 1,2-di-(p-XC 6H4)ethanes (X=H, Br, NO2) in crystalline phase, liquid and solutions at various temperatures have been investigated. Band fitting was applied to conformationally sensitive regions of the spectra, and assignment of the peaks to trans and gauche conformations was performed. Enthalpy and entropy differences of the conformers (ΔH0 and ΔS0) were found to be solvent-dependent, and it is interpreted in terms of previously discovered compensation effect. The values ΔH 0 and ΔS0 for 1,2-di-(p-NO2C 6H4)ethane obtained are unusually large. © 2003 Elsevier B.V. All rights reserved.