Now to explain the trends that emerge from the chemical kinetics of DAC. From the barriers presented in Figure , the rate-determining (RD) step-that is the step that dictates the overall kinetics-for all complexes is int2 → ts2 → int3. In this oxygen atom transfer step, the peroxy-carbonate O -O bond is broken and a new bond is formed between the detached O and adjacent peroxide ligand, generating O 3 (Figure ). Since the energy cost of this step is ≥ 31.2 kcal/mol for the Group VI compounds, they do not represent kinetically feasible room-temperature reactions.