Fig.1. The decomposition process of CF3I.
3.2. Thermal decomposition mechanism of
CF3I
The computational results of geometric optimization, frequency and
energy analysis of the CF3I molecule as shown inFig.2. which suggest that the sum of electron and thermodynamic
energy of the molecule corrected by ZPE is −347.737 Hartree, and there
is no imaginary frequency in the molecule, indicating the reliability
and stability of the investigated CF3I molecule.
Besides, the bond angles of 2F─1C─5I and 4F─1C─5I in molecule have
different bond lengths, suggesting the asymmetric structure of the
molecule. And as listed in Table.1. The dissociation energy of
1C─5I (42.581 kcal·mol−1) bond is far lower than those
of other chemical bonds in CF3I molecule, indicating
that this chemical bond is relatively weak and easy to break, leading to
the formation of CF3· radicals, which can interrupt the
chain reaction of combustion and to achieve the purpose of
fire-suppression. Furthermore, a comparison of the calculated bond
energy of CF3I with that reported in the
reference17 is presented in Table.S1 ,
implying the reliability of DFT computations in this work.