Synthesis and Characterization of Manganese Tetrafluoride β‐MnF 4

The crystal structure of β‐MnF 4 has finally been elucidated. It crystallizes in the non‐centrosymmetric space group R 3 c , no. 161, h R 360, with the lattice parameters a = 19.390(3), c = 12.940(3) Å, V = 4213.3(14) Å 3 , Z = 72, T = 100 K. It is a 4 a  × 4 a superstructure of the VF 3 (FeF 3 ) structure type. The Mn atoms are coordinated octahedron‐like by F atoms, of which two are bound terminal, while the other act as μ‐bridging F atoms to other Mn atoms forming a three‐dimensional infinite network structure which can be described by the Niggli formula 3 ∞ [MnF 4/2 F 2/1 ]. Voids on the metal sites, which are occupied in the VF 3 structure, are grouped together in the shape of a “star” with approximate D 3 h symmetry. We prepared β‐MnF 4 photochemically according to the literature and obtained a phase‐pure powder as evidenced by X‐ray diffraction at room temperature. The lattice parameters are a = 19.566(3), c = 12.984(2) Å, V = 4304(1) Å 3 . IR and Raman spectra recorded on the powder show that β‐MnF 4 has also been obtained free of moisture, HF, and O 2 + containing compounds, however MnF 3 is likely present as a magnetic impurity. We observe thermal decomposition of MnF 4 to MnF 2 and not MnF 3 .