Incommensurate structures of the [CH3NH3][Co(COOH)3] compound
| Autor: | Cañadillas-Delgado, L., Mazzuca, L., Fabelo, O., Rodríguez-Velamazán, J.A., Rodríguez-Carvajal, J. |
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| Jazyk: | angličtina |
| Rok vydání: | 2019 |
| Předmět: | |
| Zdroj: | IUCrJ Zaguán. Repositorio Digital de la Universidad de Zaragoza instname IUCrJ, Vol 6, Iss 1, Pp 105-115 (2019) 'IUCrJ ', vol: 6, pages: 105-115 (2019) |
| ISSN: | 2052-2525 |
| Popis: | The temperature evolution of [CH3NH3][Co(COOH)3] on a single crystal and the crystal structure determination of intermediate incommensurate phases of [CH3NH3][Co(COOH)3] by means of neutron diffraction are presented. The present article is devoted to the characterization of the structural phase transitions of the [CH3NH3][Co(COOH)3] (1) perovskite-like metal–organic compound through variable-temperature single-crystal neutron diffraction. At room temperature, compound 1 crystallizes in the orthorhombic space group Pnma (phase I). A decrease in temperature gives rise to a first phase transition from the space group Pnma to an incommensurate phase (phase II) at approximately 128 K. At about 96 K, this incommensurate phase evolves into a second phase with a sharp change in the modulation vector (phase III). At lower temperatures (ca 78 K), the crystal structure again becomes commensurate and can be described in the monoclinic space group P21/n (phase IV). Although phases I and IV have been reported previously [Boča et al. (2004). Acta Cryst. C60, m631–m633; Gómez-Aguirre et al. (2016). J. Am. Chem. Soc. 138, 1122–1125; Mazzuca et al. (2018). Chem. Eur. J. 24, 388–399], phases III and IV corresponding to the Pnma(00γ)0s0 space group have not yet been described. These phase transitions involve not only the occurrence of small distortions in the three-dimensional anionic [Co(HCOO)3]− framework, but also the reorganization of the [CH3NH3]+ counter-ions in the cavities of the structure, which gives rise to an alteration of the hydrogen-bonded network, modifying the electrical properties of compound 1. |
| Databáze: | OpenAIRE |
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