DFT study on the reaction mechanisms of polyfluorosulfonate ester with F−

Gas-phase reaction of C(1)F3S(2)O2O(3)C(4)H2C(5)F3 and F−(16) is investigated using DFT method. The geometries of various stationary points and their relative energies are obtained from 6-31+G*, 6-311G**, and 6-311++G** levels. In the SN2(C) reaction leading to the cleavage of the C(4)-O(3) bond, the reaction complex results from attacking of F− at a hydrogen atom H11 attached to carbon atom C(4). Afterward, F− is attacking the atom C(4) from the backside of the atom O(3) with the help of the neighboring effect, and meanwhile a multi-membered ring, F(16)-H(11)-C(4)-C(5)-F(16), is being formed. The SN2(C) reaction is irreversible. On the contrary, the SN2(S) reaction leading to the cleavage of the S(2)-O(3) bond is reversible, and it is initiated by attacking of F− at the atom S(2) from the backside of the atom O(3). The products of the reaction CF3SO3CH2CF3 +F− should be, thermodynamically, controlled due to the reversibility of the SN2(S) reaction, and those result, chemospecifically, from the cleavage of the C-O bond. At last, the SCRF calculations confirm that the solvent effect is preferable to the SN2(C) reaction.