{"title":"Isotypism and phase transitions of (NH4)M(HSO4)(SO4)(H2O)2 (M = Fe, Co and Ni) compounds","authors":"Matthias Weil","doi":"10.1107/S2056989025006395","DOIUrl":null,"url":null,"abstract":"<div><div>The (NH<sub>4</sub>)<em>M</em>(HSO<sub>4</sub>)(SO<sub>4</sub>)(H<sub>2</sub>O)<sub>2</sub> (<em>M</em> = Fe, Co, Ni) compounds are isotypic and exhibit a phase transition from an ordered crystal structure at <em>T</em> = 100 K to a disordered crystal structure at <em>T</em> = 296 K.</div></div><div><div>A systematic crystallization study of {(NH<sub>4</sub>)[<em>M</em>(HSO<sub>4</sub>)(SO<sub>4</sub>)(H<sub>2</sub>O)<sub>2</sub>]}<sub><em>n</em></sub> compounds, <em>catena</em>-poly[ammonium [[diaquametal(II)]-μ-(hydrogen sulfato)-μ-sulfato]], revealed that crystals of the <em>M</em> = Fe, Co and Ni members could be grown by evaporation of mixed equimolar aqueous solutions of NH<sub>4</sub>HSO<sub>4</sub> and the corresponding <em>M</em>SO<sub>4</sub> sulfate, whereas for <em>M</em> = Mn, Cu, Zn different products were obtained under these conditions. The (NH<sub>4</sub>)<em>M</em>(HSO<sub>4</sub>)(SO<sub>4</sub>)(H<sub>2</sub>O)<sub>2</sub> compounds (<em>M</em> = Fe, Co, Ni) show a similar behavior to the magnesium analogue, <em>i.e.</em> a reversible structural phase transition from an ordered triclinic crystal structure at <em>T</em> = 100 K (<em>Z</em> = 2) to a disordered triclinic structure at <em>T</em> = 296 K (<em>Z</em> = 1). The symmetry relationship between the structure at 296 K and the superstructure at 100 K is of the isomorphic type with index 2. At 100 K, the [<em>M</em>O<sub>4</sub>(OH<sub>2</sub>)<sub>2</sub>] octahedra are linked by distinct [SO<sub>3</sub>(OH)] and [SO<sub>4</sub>] tetrahedra into chains. Adjacent chains are linked by very strong hydrogen bonds (O⋯O ≃ 2.5 Å) between the two types of sulfate tetrahedra into layers. These layers are held together by hydrogen-bonding interactions of medium-to-weak strength between the ammonium cations and water molecules. At 296 K, the H atoms of the ammonium tetrahedron and the H atom between two symmetry-related sulfate groups are disordered. Quantitative structural comparisons are made between the isotypic (NH<sub>4</sub>)<em>M</em>(HSO<sub>4</sub>)(SO<sub>4</sub>)(H<sub>2</sub>O)<sub>2</sub> structures (<em>M</em> = Mg, Fe, Co, Ni) at 296 K and 100 K, respectively.</div></div>","PeriodicalId":7367,"journal":{"name":"Acta Crystallographica Section E: Crystallographic Communications","volume":"81 8","pages":"Pages 727-732"},"PeriodicalIF":0.6000,"publicationDate":"2025-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Acta Crystallographica Section E: Crystallographic Communications","FirstCategoryId":"1085","ListUrlMain":"https://www.sciencedirect.com/org/science/article/pii/S2056989025001392","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q4","JCRName":"CRYSTALLOGRAPHY","Score":null,"Total":0}
引用次数: 0
Abstract
The (NH4)M(HSO4)(SO4)(H2O)2 (M = Fe, Co, Ni) compounds are isotypic and exhibit a phase transition from an ordered crystal structure at T = 100 K to a disordered crystal structure at T = 296 K.
A systematic crystallization study of {(NH4)[M(HSO4)(SO4)(H2O)2]}n compounds, catena-poly[ammonium [[diaquametal(II)]-μ-(hydrogen sulfato)-μ-sulfato]], revealed that crystals of the M = Fe, Co and Ni members could be grown by evaporation of mixed equimolar aqueous solutions of NH4HSO4 and the corresponding MSO4 sulfate, whereas for M = Mn, Cu, Zn different products were obtained under these conditions. The (NH4)M(HSO4)(SO4)(H2O)2 compounds (M = Fe, Co, Ni) show a similar behavior to the magnesium analogue, i.e. a reversible structural phase transition from an ordered triclinic crystal structure at T = 100 K (Z = 2) to a disordered triclinic structure at T = 296 K (Z = 1). The symmetry relationship between the structure at 296 K and the superstructure at 100 K is of the isomorphic type with index 2. At 100 K, the [MO4(OH2)2] octahedra are linked by distinct [SO3(OH)] and [SO4] tetrahedra into chains. Adjacent chains are linked by very strong hydrogen bonds (O⋯O ≃ 2.5 Å) between the two types of sulfate tetrahedra into layers. These layers are held together by hydrogen-bonding interactions of medium-to-weak strength between the ammonium cations and water molecules. At 296 K, the H atoms of the ammonium tetrahedron and the H atom between two symmetry-related sulfate groups are disordered. Quantitative structural comparisons are made between the isotypic (NH4)M(HSO4)(SO4)(H2O)2 structures (M = Mg, Fe, Co, Ni) at 296 K and 100 K, respectively.
期刊介绍:
Acta Crystallographica Section E: Crystallographic Communications is the IUCr''s open-access structural communications journal. It provides a fast, simple and easily accessible publication mechanism for crystal structure determinations of inorganic, metal-organic and organic compounds. The electronic submission, validation, refereeing and publication facilities of the journal ensure rapid and high-quality publication of fully validated structures. The primary article category is Research Communications; these are peer-reviewed articles describing one or more structure determinations with appropriate discussion of the science.