Antiferromagnetic Alkali Metal Oxohydroxoferrates(III) with Correlated Hydrogen Bonding Systems
Abstract The oxohydroxoferrates(III) A2[Fe2O3(OH)2] (A=K, Rb, Cs) were synthesized under hydroflux conditions. Approximately equimolar mixtures of the alkali metal hydroxides and water were reacted with Fe(NO3)3 ⋅ 9H2O at about 200 °C. The product formation depends on the hydroxide concentration, th...
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doaj-c9dddfb682804538abd171a532aa5c8e2021-04-02T11:36:15ZengWiley-VCHChemistryOpen2191-13632019-12-018121399140610.1002/open.201900287Antiferromagnetic Alkali Metal Oxohydroxoferrates(III) with Correlated Hydrogen Bonding SystemsRalf Albrecht0Dr. Jens Hunger1Dr. Markus Hölzel2Theresa Block3Prof. Dr. Rainer Pöttgen4Prof. Dr. Thomas Doert5Prof. Dr. Michael Ruck6Faculty of Chemistry and Food Chemistry Technische Universität Dresden 01069 Dresden GermanyFaculty of Chemistry and Food Chemistry Technische Universität Dresden 01069 Dresden GermanyForschungsneutronenquelle Heinz Maier-Leibnitz (FRM II) Technische Universität München Lichtenbergstraße 1 85747 Garching GermanyInstitut für Anorganische und Analytische Chemie Universität Münster Corrensstraße 30 48149 Münster GermanyInstitut für Anorganische und Analytische Chemie Universität Münster Corrensstraße 30 48149 Münster GermanyFaculty of Chemistry and Food Chemistry Technische Universität Dresden 01069 Dresden GermanyFaculty of Chemistry and Food Chemistry Technische Universität Dresden 01069 Dresden GermanyAbstract The oxohydroxoferrates(III) A2[Fe2O3(OH)2] (A=K, Rb, Cs) were synthesized under hydroflux conditions. Approximately equimolar mixtures of the alkali metal hydroxides and water were reacted with Fe(NO3)3 ⋅ 9H2O at about 200 °C. The product formation depends on the hydroxide concentration, therefore also other reaction products, such as KFeO2, K2−x[Fe4O7−x(OH)x] or α‐Fe2O3, are obtained. The crystal structures of the oxohydroxoferrates(III) A2[Fe2O3(OH)2] follow the same structural principle, yet differ in their layer stacking or/and their hydrogen bonding systems depending on A and temperature. In the resulting four different orthorhombic structure types, [FeO3OH]4− tetrahedra share their oxide corners to create folded ∞2[ Fe2O3(OH)2]2− layers. The terminal hydroxide ligands form hydrogen bonds between and/or within the layers. The positions of the hydrogen atoms in these networks are correlated. The A+ cations are located between the folded anionic layers as well as in their trenches. Under reaction conditions, the potassium compound crystallizes in the space group Cmce (Pearson symbol oC88), showing a bimodal disorder of the hydrogen atoms in hydrogen bridges. In a virtually hysteresis‐less first‐order transition at 340(2) K, the structure slightly distorts into the room‐temperature modification with the subgroup Pbca (oP88), and the hydrogen atoms order. The rubidium and caesium compounds are isostructural to each other but not to the potassium compound, and are always obtained as mixtures of two modifications with space groups Cmce (oC88′) and Immb (oI88). Upon heating, the oxohydroxoferrates decompose into their anhydrides AFeO2 and water. The type of hydrogen bonding network influences the decomposition temperature, the structure and the morphology of the crystals. Despite the presence of iron(III), which was confirmed by 57Fe‐Mössbauer spectroscopy, K2[Fe2O3(OH)2] is diamagnetic in the investigated temperature range between 1.8 and 300 K. Neutron diffraction revealed strong antiferromagnetic coupling of the magnetic moments, which are inverted in neighboring tetrahedra.https://doi.org/10.1002/open.201900287oxohydroxoferratescrystal structurehydrofluxmagnetic structurethermal analysis |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
Ralf Albrecht Dr. Jens Hunger Dr. Markus Hölzel Theresa Block Prof. Dr. Rainer Pöttgen Prof. Dr. Thomas Doert Prof. Dr. Michael Ruck |
spellingShingle |
Ralf Albrecht Dr. Jens Hunger Dr. Markus Hölzel Theresa Block Prof. Dr. Rainer Pöttgen Prof. Dr. Thomas Doert Prof. Dr. Michael Ruck Antiferromagnetic Alkali Metal Oxohydroxoferrates(III) with Correlated Hydrogen Bonding Systems ChemistryOpen oxohydroxoferrates crystal structure hydroflux magnetic structure thermal analysis |
author_facet |
Ralf Albrecht Dr. Jens Hunger Dr. Markus Hölzel Theresa Block Prof. Dr. Rainer Pöttgen Prof. Dr. Thomas Doert Prof. Dr. Michael Ruck |
author_sort |
Ralf Albrecht |
title |
Antiferromagnetic Alkali Metal Oxohydroxoferrates(III) with Correlated Hydrogen Bonding Systems |
title_short |
Antiferromagnetic Alkali Metal Oxohydroxoferrates(III) with Correlated Hydrogen Bonding Systems |
title_full |
Antiferromagnetic Alkali Metal Oxohydroxoferrates(III) with Correlated Hydrogen Bonding Systems |
title_fullStr |
Antiferromagnetic Alkali Metal Oxohydroxoferrates(III) with Correlated Hydrogen Bonding Systems |
title_full_unstemmed |
Antiferromagnetic Alkali Metal Oxohydroxoferrates(III) with Correlated Hydrogen Bonding Systems |
title_sort |
antiferromagnetic alkali metal oxohydroxoferrates(iii) with correlated hydrogen bonding systems |
publisher |
Wiley-VCH |
series |
ChemistryOpen |
issn |
2191-1363 |
publishDate |
2019-12-01 |
description |
Abstract The oxohydroxoferrates(III) A2[Fe2O3(OH)2] (A=K, Rb, Cs) were synthesized under hydroflux conditions. Approximately equimolar mixtures of the alkali metal hydroxides and water were reacted with Fe(NO3)3 ⋅ 9H2O at about 200 °C. The product formation depends on the hydroxide concentration, therefore also other reaction products, such as KFeO2, K2−x[Fe4O7−x(OH)x] or α‐Fe2O3, are obtained. The crystal structures of the oxohydroxoferrates(III) A2[Fe2O3(OH)2] follow the same structural principle, yet differ in their layer stacking or/and their hydrogen bonding systems depending on A and temperature. In the resulting four different orthorhombic structure types, [FeO3OH]4− tetrahedra share their oxide corners to create folded ∞2[ Fe2O3(OH)2]2− layers. The terminal hydroxide ligands form hydrogen bonds between and/or within the layers. The positions of the hydrogen atoms in these networks are correlated. The A+ cations are located between the folded anionic layers as well as in their trenches. Under reaction conditions, the potassium compound crystallizes in the space group Cmce (Pearson symbol oC88), showing a bimodal disorder of the hydrogen atoms in hydrogen bridges. In a virtually hysteresis‐less first‐order transition at 340(2) K, the structure slightly distorts into the room‐temperature modification with the subgroup Pbca (oP88), and the hydrogen atoms order. The rubidium and caesium compounds are isostructural to each other but not to the potassium compound, and are always obtained as mixtures of two modifications with space groups Cmce (oC88′) and Immb (oI88). Upon heating, the oxohydroxoferrates decompose into their anhydrides AFeO2 and water. The type of hydrogen bonding network influences the decomposition temperature, the structure and the morphology of the crystals. Despite the presence of iron(III), which was confirmed by 57Fe‐Mössbauer spectroscopy, K2[Fe2O3(OH)2] is diamagnetic in the investigated temperature range between 1.8 and 300 K. Neutron diffraction revealed strong antiferromagnetic coupling of the magnetic moments, which are inverted in neighboring tetrahedra. |
topic |
oxohydroxoferrates crystal structure hydroflux magnetic structure thermal analysis |
url |
https://doi.org/10.1002/open.201900287 |
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