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Conclusions

Semiempirical quantum mechanics appears as a reasonable starting point to establish reactivity trends of similar types of reactions and it is possible to demonstrate that in this series of chloroethenes there is a strong correlation of the rate constant with the atomic orbital coefficients of the reactants that can be well explained by frontier molecular orbital theory. Certainly to obtain more accurate values of the geometries and the energies it is necessary to consider higher levels of ab-initio calculations.
For the chloroethenes studied in this work, the HOMO is composed carbon-carbon p bonding and halogen atom lone-pair contribution. As a result, the rate constants for these reactions do not correlate in a simple manner with the energy of the HOMO (the experimental ionization potential), as in the case in the other alkene reactions. A better description of this effect could be achieved, taking into account the perturbation term which carries the contribution of the different atomic orbitals to the HOMO of the chloroethene through the atomic orbital coefficients.