Browsing by Author "Barreda-Argüeso, JA"

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    Phase transition sequences in tetra­methyl­ammonium tetra­chloro­metallates by x-ray diffraction and spectroscopic measurements
    (International Union of Crystallography, 2017-01) Binns, J; McIntyre, GJ; Barreda-Argüeso, JA; González, J; Aguado, F; Rodríguez, F; Valiente, R; Parsons, S
    The phase transition sequences of two members of the tetra­methyl­ammonium tetra­chloro­metallate(III) family of hybrid organic–inorganic salts have been determined and structurally characterized as a function of temperature for the first time. Unusually, a reduction in point-group symmetry with increasing temperature until reaching a cubic prototype phase is observed. Two additional intermediate phases are observed for Fe3+. First-principles calculations and the presence of short Cl...Cl contacts for Ga3+ suggest the [GaCl4]− anion to be conformationally hindered due to stronger lone-pair–σ-hole interactions. The conformationally more flexible Fe3+ structures show sublattice melting with the onset of rotational disorder in the [NMe4]+ cations occurring 40 K below the corresponding onset of rotational disorder in the [FeCl4]− sublattice. © International Union of Crystallography