Polarizability effects and dispersion interactions in alkene-Br2 pi-complexes

Weakly bound molecular complexes play an important role in chemistry, physics, and biodisciplines. The preequilibrium pi-complexes of various alkenes with bromine have been examined quantitatively, and a direct relationship between association constants (KF) of these pi-complexes and polarizability of the olefins was found. The stability of the Br2-olefin pi complexes is affected by both the donor ionization potential and the polarizability of the olefin, and an equation able to take into account both effects is proposed.