Hydrogen migration in the phenylethen-2-yl radical

The migration of hydrogen in the phenylethen-2-yl radical is investigated b y determining optimal geometries and barrier and reaction energies using se veral quantum mechanical methods. Rate coefficients and equilibrium constan ts are obtained using the calculated data and RRKM theory. Theoretical meth ods compared include PM3, MP2, B3-LYP, CASPT2, and G2MP2. The applicability of these methods and comparisons with two others, G2M and CBS-RAD proposed to improve treatment of radicals, are discussed. The results obtained at t he most reliable level of theory produce reaction rates sufficiently fast f or these reactions to play a role in high-temperature aromatic chemistry.