Die Kristallstruktur der hydratisierten Cyanokomplexe NMe4MnII[(Mn, Cr)III(CN)6] · 3 H2O und NMe4Cd[MIII(CN)6] · 3 H2O (MIII = Fe,Co): Verwandte des Berliner Blaus

The Crystal Structure of the Hydrated Cyano Complexes NMe₄Mn^II[(Mn, Cr)^III(CN)₆] · 3 H₂O and NMe₄Cd[M^III(CN)₆] · 3 H₂O (M^III = Fe, Co): Compounds Related to Prussian Blue The crystal structures of the isotypic tetragonal compounds (space group I4, Z = 10) NMe₄Mn^II · [(Mn, Cr)^III(CN)₆] · 3 H₂O (a = 1653.2(4), c = 1728.8(6) pm), NMe₄Cd[Fe(CN)₆] · 3 H₂O (a = 1642.7(1), c = 1733.1(1) pm) and NMe₄Cd[Co(CN)₆] · 3 H₂O (a = 1632.1(2), c = 1722.4(3) pm) were determined by X‐rays. They exhibit ⊥ c cyanobridged layers of octahedra [M^III(CN)₆] and [M^IIN₄(OH₂)₂], which punctually are interconnected also || c to yield altogether a spaceous framework. The M^II atoms at the positions linking into the third dimension are only five‐coordinated and form square pyramids [M^IIN₅] with angles N–M^II–N near 104° and distances of Mn–N: 1 × 214, 4 × 219 pm; Cd–N: 1 × 220 resp. 222, 4 × 226 resp. 228 pm. Further details and structural relations within the family of Prussian Blue are reported and discussed.     

Prussian blue analogues as aqueous Zn-ion batteries electrodes: Current challenges and future perspectives

The urgency of integrating renewable energy sources in the power grid has pushed the development of aqueous metal-ion batteries because of their low cost, nontoxicity, high safety, and environmentally friendliness. Among the variety of aqueous metal-ion batteries that are currently under development, aqueous Zn-ion batteries (A-ZIBs) have recently gained a great attention because of their high specific energy and high reversibility in aqueous solutions, together with the low cost and high abundancy of the zinc. In this article, the authors intend to present an overview of the Prussian blue analogue materials, which are among the most promising materials for positive electrodes in A-ZIBs because of their easier synthesis route, reversible ion-insertion, high safety, and low toxicity, highlighting their strength points and open challenges.     

Kristallstrukturbestimmungen an Cs2NaCr(CN)6 und weiteren Verbindungen A2BM(CN)6 (A = Rb,Cs; B = Na,K, Rb,NH4; M = Cr,Mn, Fe,Co): Oktaederkippung und Toleranzfaktor von Cyanokryolithen

Crystal Structure Determinations of Cs₂NaCr(CN)₆ and further Compounds A₂BM(CN)₆ (A = Rb, Cs; B = Na, K, Rb, NH₄; M = Cr, Mn, Fe, Co): Tilting of Octahedra and Tolerance Factor of Cyano Cryolites The crystal structures of Cs₂NaCr(CN)₆ (space group P2₁/n, Z = 2; a = 763.2(1), b = 789.8(1), c = 1102.4(1) pm, β = 90.09(1)°) and of 9 isostructural cyano cryolites A₂BM(CN)₆ of the elements M = Cr, Mn, Fe, Co were determined by X‐rays at single crystals. The results, including data from the literature, were studied with respect to the interdependence of radii resp. bond lengths and cyano bridge angles M–CN–B resp. tilting of [M(CN)₆] and [BN₆] octahedra: The average tilt angles κ of the latter are within the range 13° ≤ κ ≤ 23° and increase linearly if the modified tolerance factor t (of range 0,87 ≥ t ≥ 0,78) decreases.