Comment on "Theoretical investigations on hydrogen peroxide decomposition in aquo" by T. Tsuneda and T. Taketsugu, Phys. Chem. Chem. Phys., 2018, 20, 24992.

In an ab initio study, Tsuneda and Taketsugu (Phys. Chem. Chem. Phys., 2018, 20, 24992-24999) discuss the Fenton reaction, the reaction of Fe2+ with H2O2. They claim that reaction is endergonic and therefore introduce a new intermediate, a de facto monovalent iron complex. I show here that kinetically and thermodynamically such a monovalent iron complex cannot be formed.