Acta Cryst. (2008). E64, o667  [ doi:10.1107/S1600536808004339 ]

The low-temperature phase of morpholinium tetrafluoroborate

M. Owczarek, P. Szklarz, R. Jakubas and T. Lis

Abstract: The crystal structure of the low-temperature form of the title compound, C₄H₁₀NO⁺·BF₄^-, was determined at 80 K. Two reversible phase transitions, at 158/158 and 124/126 K (heating/cooling), were detected by differential scanning calorimetry for this compound, and the sequence of phase transitions was subsequently confirmed by single-crystal X-ray diffraction experiments. The asymmetric unit at 80 K consists of three BF₄^- tetrahedral anions and three morpholinium cations (Z' = 3). Hydrogen-bonded morpholinium cations form chains along the [100] direction. The BF₄^- anions are connected to these chains by N-HF hydrogen bonds. In the crystal structure, two different layers perpendicular to the [001] direction can be distinguished, which differ in the geometry of the hydrogen bonds between cationic and anionic species.

Online 5 March 2008

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