The mechanism of the reaction F-2 + 2HCl-->2HF + Cl-2 has been investigated
using density functional theory(DFT) at the B3LYP/6 - 311G** level. The tr
ansition states for all the possible reaction paths are obtained and verifi
ed by vibrational analyses and IRC calculations. By comparing the calculate
d barriers, it is found that the largest barrier for the mechanism of molec
ule - molecule interaction is 150.63kJ . mol(-1). The corresponding barrier
for the mechanism in which F-2 is cleavaged first before the resulting F a
toms react with the other reactants is 154.82kJ. For the reaction F + HCl--
>HF + Cl, two types of transition states are located. One is linear, the an
other is triangle and it is more stable. Between two transition states for
the reaction HCl+ Cl-->H + Cl-2, the linear one is more stable.