The regularities in the regioselectivity of phenylation of alkenes (th
e Heck reaction) were studied by the multiple regression method using
equations of the MO perturbation theory and HSAB principle. The additi
on of Ar to sterically nonhindered alkenes was established to be indep
endent of the effective charge distribution on the carbon atom of the
vinyl group and correlate best of all with the contributions of their
AO to LUMO of the alkene. This is indicative of the orbital control of
the reaction, and the stage of the electron transfer from the palladi
um atom to the alkene molecule plays the key role.