Density Functional Theory as a Predictive Tool for Cerium Redox Properties in Nonaqueous Solvents.

Two methods to correlate and predict experimental redox potentials for cerium complexes were evaluated. Seventeen previously reported cerium complexes were computed using DFT methods in both the CeIII and CeIV oxidation states with a dichloromethane solvent continuum. In the first computational approach, the ΔGo(CeIV/CeIII) was determined for each of the compounds and these values were correlated with the experimental E1/2 values measured in dichloromethane, referenced to the ferrocene/ferrocenium couple. The second method involved correlating the energies of the CeIV LUMOs (lowest unoccupied molecular orbitals) with the experimental redox potentials, E1/2. The predictive capabilities of these two correlative methods were tested using a new cerium hydroxylamine complex, Ce(ODiNOx)2 (ODiNOx = bis(2-tert-butylhydroxylaminatobenzyl) ether). All 18 complexes studied in this paper were combined with the 15 complexes determined in acetonitrile from a previously published correlation by our group. These sets of data allowed us to develop two methods for predicting the redox potential of cerium complexes regardless of the solvent for the experimental measurement.