Cover Feature: Unravelling the mechanisms behind oxidative transformations of vivianite and parasymplesite into previously not recognized materials with unexpected oxidation states of iron – a systematic review (Z. Anorg. Allg. Chem. 21/2023)

The cover picture shows the local changes at the mono-octahedral iron sites of {[Fe(a‘)Fe(a)2(XO4)2(H2O)8]}∞ (X=P: vivianite or As: parasymplesite) during stepwise oxidation via {[Fe(a‘)Fe(a)2(XO4)2(HO)2(H2O)6]}∞ to the final products {[Fe(a‘)Fe(a)2(XO4)2(HO)4(H2O)4]}∞. Rather unexpected, the volume of the FeO6 octahedron of the arsenate series decreases to approx. 75% of its initial value, compatible with a jump in the oxidation state from +2 to +4. Since the effects in the phosphate series are of similar magnitude, we are most probably faced with the first examples of unexpectedly high oxidation states of iron in compounds with complex chalcogenido anions (DOI: 10.1002/zaac.202300143).