Theoretical Study on Fluoro Substitution Effect of the Transfer Reaction of Inner Hydrogen Atoms in Porphyrin
- Received Date: 2004-10-26
- Inner hydrogen atom transfer (NH tautomerization), Transition state, Second-order saddlepoint, Fluoro substitent, Substitution effect /
Abstract: The structures and energies of reactant, product, intermediate, transition and second order saddlepoint in the transfer reaction of inner hydrogen atoms in porphine(PH2), m-tetra-fluorineporphyrin(m-TFPH2), β-octa-fluorine-porphyrin (β-OFPH2) and m-tetra-fluorine, β-octa-fluorine-porphyrin(12FPH2) were calculated by using B3LYP/6-31G** method under certain symmetry restriction. In the transfer reaction of inner hydrogen atoms in all various matters， the comparison of structures and the energies shows that the probabilities of asynchronous mechanism are larger than that of synchronous mechanism via a second-order saddle-point, and substitutents to porphyrin in hydrogen migration have no influence on mechanism choice. But the substitutents can affect speed differences between the synchronous mechanisms and the asynchronous mechanisms. In addition, fluoro substitutents decrease speeds of positive and negative reactions in asynchronous mechanisms, which is in agreement with chemical intuition.
|Citation:||Liao Yuting, Rao Huoyu, Kong Fanfeng, Luo Mingbiao. Theoretical Study on Fluoro Substitution Effect of the Transfer Reaction of Inner Hydrogen Atoms in Porphyrin[J]. Chinese Journal of Chemical Physics , 2005, 18(5): 750-758. doi: 10.1088/1674-0068/18/5/750-758|