In this paper, a comparison between "static" and "dynamic" determination of the thermodynamic (A,F) and kinetic data (Delta(r)F(#)) for the reaction of Cl2LaR (R = H, CH3) and H-2 is given. A difference is obtained in the case of the reaction between Cl2LaH and H-2 and can be attributed to a failure of the "static" approach based on the harmonic approximation. The influence of the zero point energy correction is also analyzed but does not explain the 30% difference between the two calculated activation energies. The influence of the flatness of the potential energy surface around the transition state is proved as no such an effect is observed for the reaction of Cl2LaCH3 and H-2.