Figure 2. Correlation between changes in the Gibbs free energy
(∆G) for the A- + CO2 reactions in the
gas phase and the gas phase basicity (GPB) of the anions. Also indicated
is the square of the residuals.
The nature of the atom that interacts with CO2determines the changes in the Gibbs free energies (figure 3).
Specifically, the reactions with anions containing nitrogen atoms are
found to be more spontaneous than those with analog anions containing
oxygen, followed by those containing phosphorous and then sulfur atoms
(Figure 3). The anions CH3-,
H-, NH2- and
OH-, which do not have any special stabilization
effect and are small species, are among those leading to the most
negative change in the Gibbs free energy.