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Incommensurate structures of the [CH3NH3][Co(COOH)3] compound.
IUCrJ ; 6(Pt 1): 105-115, 2019 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-30713708
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 [Boca 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.





Texto completo: Disponível Coleções: Bases de dados internacionais Base de dados: MEDLINE Idioma: Inglês Revista: IUCrJ Ano de publicação: 2019 Tipo de documento: Artigo País de afiliação: França