Theoretical Studies on the Higher Oxidation States of Iron.
Density functional theory (DFT) and multiconfiguration self-consistent field (MCSCF) calculations on the oxo FeO(4)(2)(-) (Fe(VI)) and the hypothetical oxo FeO(4)(-) (Fe(VII)), and FeO(4) (Fe(VIII)) and peroxo FeO(2)(O-O)(z)() [z = -2 (Fe(IV)), z = -1 (Fe(V)), z = 0 (Fe(VI))], Fe(O-O)(2)(z)() [z = -2 (Fe(II)), z = -1 (Fe(III)), z = 0 (Fe(IV))], and FeO(O-O)(2)(z)() [z = -2 (Fe(IV)), z = -1 (Fe(V)), z = 0 (Fe(VI))] clusters are presented and discussed. The results show the potential of stabilizing Fe(VII) and Fe(VIII) in tetrahedral oxo coordination. On the basis of absolute electronegativities calculated using DFT, it is predicted that FeO(4) will be rather oxidizing, even stronger than Cl(2) and O(2). On the basis of a comparison between total bonding energies of M(1)M(2)Fe(VI)O(4) (M(1), M(2) = Li, K), MFe(VII)O(4) (M = Li, K), and Fe(VI)O(4) clusters, possible synthetic routes for electrochemical preparation of FeO(4)(-) and FeO(4) species are discussed.
Atanasov
M.
M
Institute of General and Inorganic Chemistry, Bulgarian Academy of Sciences, Bl.11, 1113 Sofia, Bulgaria, and Fachbereich Chemie und Zentrum für Materialwissenschaften der Philipps-Universität, Hans-Meerweinstrasse 1, D-35043 Marburg, Germany.