Results

We assume, as is usually done, that the initial step in Fenton and Fenton-like chemistry is the nucleophilic addition of hydrogen peroxide to the iron complex by exchanging with a water ligand in the hydration shell[196]. In the next section (6.3.1), we discuss the energetics of various reactions starting from the [Fe$^{\rm {II}}$(H$_2$O)$_5$(H$_2$O$_2$)]$^{2+}$ and the [Fe$^{\rm {III}}$(H$_2$O)$_5$(H$_2$O$_2$)]$^{3+}$ complexes in order to investigate the thermodynamic possibilities and impossibilities. Figure 6.1 shows the geometry optimized structures of these two complexes in vacuo. Later on, in section 6.3.2, we will show an illustrative pathway of the reaction of H$_2$O$_2$ with Fe$^{3+}$ in water, which includes the coordination process.

Figure: Optimized ground-state structures of [Fe$^\mathrm{III}$(H$_2$O)$_5$(H$_2$O$_2$)]$^{3+}$ (left-hand-side) and [Fe$^\mathrm{II}$(H$_2$O)$_5$(H$_2$O$_2$)]$^{2+}$ (right-hand-side).