Density functional theory and ab initio study of electronic and electrochemistry properties of the tetranuclear sandwich complex [FeIII4(H2O)2(PW9O34)2]6-.

Quantum chemistry calculations have been performed to unravel the electronic and electrochemical properties of a FeIII-sandwich polyoxometalate. Using a combination of methods, it is shown that in these clusters the first reduction occurs in the so-called external Fe, which is bonded to a water ligand. Calculations also show that the electron reductions are coupled with protonation processes, in full agreement with existing experimental results.