Proton transfer in C-halogen pyrazole cyclamers.: A theoretical study

Four monomers and twelve pyrazole cyclamers unsubstituted or bearing fluoro, chloro, or bromo substituents at positions 3 and 5 have been studied at the B3LYP/6-31+G** theoretical level. Two mechanisms of proton transfer, stepwise and synchronous, have been studied for dimers, trimers, and tetramers. Even though some values of the barriers have not been determined, the set of values of energies and geometries provide useful insights about the dynamics of NH-pyrazoles in the solid state.