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- Title
Polymorphous transformation in the crystal structure of [Mg(H<sub>2</sub>O)<sub>6</sub>Br<sub>2</sub>][(C<sub>7</sub>H<sub>14</sub>N<sub>4</sub>)<sub>2</sub>] · 4 (H<sub>2</sub>O) studied by powder and single crystal X-ray diffraction.
- Authors
Rivera, Augusto; Rohlíček, Jan; Sadat-Bernal, John; Ríos-Motta, Jaime; Dušek, Michal
- Abstract
The supramolecular complex [Mg(H2O)6Br2] · [(C7H14N4)2] · 4 (H2O) ( 1) was synthesized and characterized by combination of techniques as NMR, FT-IR, elemental analysis and argentometric titration. The molecular structure was evidenced by X-ray crystallography. It underwent a spontaneous phase transition to a second monoclinic phase ( 2). Phase ( 1) crystallizes in the monoclinic space group P21/ c with a = 13.79430(12), b = 14.80930(13), c = 14.29182(12) Å, β = 91.3976(5)°, and Z = 4. The crystal structure was partially solved by direct methods from intensities obtained from a microcrystal of the material measured by single-crystal method, and finalized from powder data. The second phase ( 2) with monoclinic space group P21/ a, a = 9.19007(6), b = 21.38080(17), c = 8.12027(6) Å, β = 113.7766(5)°, and Z = 2, was solved from powder data, ab initio, by a charge flipping algorithm. The diffraction experiments showed an irreversible phase change occurs as a function of temperature with apparent gain of thermodynamic stability.
- Subjects
CRYSTAL structure research; SINGLE crystals; X-ray diffraction; FOURIER transform infrared spectroscopy; X-ray crystallography; POLYMORPHISM (Crystallography)
- Publication
Zeitschrift für Kristallographie. Crystalline Materials, 2014, Vol 229, Issue 4, p319
- ISSN
2194-4946
- Publication type
Article
- DOI
10.1515/zkri-2013-1672