Experimental and theoretical determination of the accurate interaction energies in benzene-halomethane: the unique nature of the activated CH/pi interaction of haloalkanes.

The CH/pi interaction energies between benzene and halomethanes (CH(2)Cl(2) and CHCl(3)) were accurately determined. Two-color ionization spectroscopy was applied to the benzene-CH(2)Cl(2) and -CHCl(3) clusters, and the binding energies in the neutral ground state, i.e.