The structures and phase transitions in 4-aminopyridinium tetraaquabis(sulfato)iron(III), (C5H7N2)[FeIII(H2O)4(SO4)2]

Autor:	Michal Dušek, Vasyl Kinzhybalo, Wolfgang Hornfeck, Tamara J. Bednarchuk, Zhengyang Zhou, Adam Pietraszko
Rok vydání:	2019
Předmět:	Diffraction Phase transition 010405 organic chemistry Chemistry Metals and Alloys Triclinic crystal system Atmospheric temperature range 010402 general chemistry 01 natural sciences Atomic and Molecular Physics and Optics 0104 chemical sciences Electronic Optical and Magnetic Materials Crystallography Differential scanning calorimetry Octahedron Materials Chemistry Crystal twinning Monoclinic crystal system
Zdroj:	Acta Crystallographica Section B Structural Science, Crystal Engineering and Materials. 75:1144-1151
ISSN:	2052-5206
DOI:	10.1107/s2052520619013155
Popis:	The organic–inorganic hybrid compound 4-aminopyridinium tetraaquabis(sulfato)iron(III), (C5H7N2)[FeIII(H2O)4(SO4)2] (4apFeS), was obtained by slow evaporation of the solvent at room temperature and characterized by single-crystal X-ray diffraction in the temperature range from 290 to 80 K. Differential scanning calorimetry revealed that the title compound undergoes a sequence of three reversible phase transitions, which has been verified by variable-temperature X-ray diffraction analysis during cooling–heating cycles over the temperature ranges 290–100–290 K. In the room-temperature phase (I), space groupC2/c, oxygen atoms from the closest Fe-atom environment (octahedral) were disordered over two equivalent positions around a twofold axis. Two intermediate phases (II), (III) were solved and refined as incommensurately modulated structures, employing the superspace formalism applied to single-crystal X-ray diffraction data. Both structures can be described in the (3+1)-dimensional monoclinicX2/c(α,0,γ)0ssuperspace group (whereXis ½, ½, 0, ½) with modulation wavevectorsq= (0.2943, 0, 0.5640) andq= (0.3366, 0, 0.5544) for phases (II) and (III), respectively. The completely ordered low-temperature phase (IV) was refined with the twinning model in the triclinicP{\overline 1} space group, revealing the existence of two domains. The dynamics of the disordered anionic substructure in the 4apFeS crystal seems to play an essential role in the phase transition mechanisms. The discrete organic moieties were found to be fully ordered even at room temperature.
Databáze:	OpenAIRE
Externí odkaz:	https://explore.openaire.eu/search/publication?articleId=doi_________::48241689eb1de228ff0800c44d4b1c47 https://doi.org/10.1107/s2052520619013155 Zobrazit plný text záznamu Plný text ve formátu PDF Plný text ve formátu HTML
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