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).

中文翻译：

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封面专题：揭示六铁矿和副铁矿氧化转化成以前未识别的具有意想不到的铁氧化态材料的机制——系统综述（Z. Anorg. Allg. Chem. 21/2023）

_{封面图片显示了 {[Fe(a')Fe(a) 2} (XO ₄ ) ₂ (H ₂ O) ₈ ]} _∞ (X=P: 紫铁矿或 As:的单八面体铁位点的局部变化：副共矿）通过 {[Fe(a')Fe(a) ₂ (XO ₄ ) ₂ (HO) ₂ (H ₂ O) ₆ ]} _∞逐步氧化为最终产物 {[Fe(a')Fe(a ) ₂ (XO ₄ ) ₂ (H2O) ₄ (H ₂ O) ₄ ]} _∞。_{相当出乎意料的是，砷酸盐系列的FeO 6}八面体的体积减小至约。其初始值的 75%，与氧化态从 +2 跃升至 +4 兼容。由于磷酸盐系列的影响程度相似，我们很可能面临第一个例子，即具有复杂硫族阴离子的化合物中铁的氧化态出人意料地高（DOI：10.1002/zaac.202300143）。