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

Abstract

The formation of complexes between hexafluorobenzene and the Lewis bases dimethyl ether, dimethyl ether-d6, trimethylamine and trimethylamine-d9 was investigated experimentally using FTIR spectroscopy on solutions of liquid krypton. Additional bands found in the spectra of mixtures were assigned to lone pair···π complexes using ab initio calculations at the MP2/aug-cc-pVDZ level. By constructing Van ‘t Hoff plots, experimental complexation enthalpies were determined of −6.0(6)kJmol−1 for the complex with dimethyl ether(-d6) and −6.7(9)kJmol−1 for the complex with trimethylamine(-d9). These values are in good agreement with calculated enthalpy values.