Combined ab initio MO and experimental studies on unimolecular hydrogen fluoride loss from protonated fluorobenzene in the gas phase

Abstract

The unimolecular loss of hydrogen fluoride from protonated fluorobenzene was studied by chemical ionization mass spectrometry and MP2/6-31G * ab initio MO calculations. Kinetic energy release measurements point to of three distinct pathways. In addifion to direct HF loss from the fluorine-protonated molecule, the calculations reveal the coexistence of 1,1- and 1,2-elimination process, both derived from ring-protonated isomers. The structures and energetics of the relevant minima and transifion structures have been determined, and the combined experimental/theoretical findings point to a uniquesituation in which protonation of the same precursor molecule by different BrOnsfed acids Affords identical products via three different reaction channels