Using biprotonated dabco (1,4-diazabicyclo[2.2.2]octane) or pipz (piperazine) as counter cations, mixed-ligand fluoromanganates(III) with dimeric anions could be prepared from hydrofluoric acid solutions. The crystal structures were determined by X-ray diffraction on single crystals: dabcoH2[Mn2F8(H2O)2]·2H2O (1), space group P21, Z = 2, a = 6.944(1), b = 14.689(3), c = 7.307(1) Å, β = 93.75(3)°, R1 = 0.0240; pipzH2[Mn2F8(H2O)2]·2H2O (2), space group P1¯, Z = 2, a = 6.977(1), b = 8.760(2), c = 12.584(3) Å, α = 83.79(3), β = 74.25(3), γ = 71.20(3)°, R1 = 0.0451; (dabcoH2)2[Mn2F8(H2PO4)2] (3), space group P21/n, Z = 4, a = 9.3447(4), b = 12.5208(4), c = 9.7591(6) Å, β = 94.392(8)°, R1 = 0.0280. All three compounds show dimeric anions formed by [MnF5O] octahedra (O from oxo ligands) sharing a common edge, with strongly asymmetric double fluorine bridges. In contrast to analogous dimeric anions of Al or Fe(III), the oxo ligands (H2O (1,2) or phosphate (3)) are in equatorial trans-positions within the bridging plane. The strong pseudo-Jahn–Teller effect of octahedral Mn(III) complexes is documented in a huge elongation of an octahedral axis, namely that including the long bridging Mn–F bond and the Mn–O bond. In spite of different charge of the anion in the fluoride phosphate, the octahedral geometry is almost the same as in the aqua-fluoro compounds. The strong distortion is reflected also in the ligand field spectra.Graphical abstractdabcoH2[Mn2F8(H2O)2]·2H2O, pipzH2[Mn2F8(H2O)2]·2H2O and (dabcoH2)2[Mn2F8(H2PO4)2] show dimeric anions with highly asymmetrical double bridges due to strong Jahn–Teller distortion.Highlights► New dimeric anions [MnIII2F8(H2O)2]2− and [MnIII2F8(H2PO4)2]4− with double F-bridges. ► Strong asymmetry of the Mn–F–Mn bridges due to Jahn–Teller distortion. ► trans-Equatorial position of the oxo ligands by Jahn–Teller stabilization.

A new compound—the first titanium vanadyl(V) phosphate Cs2[Ti(VO2)3(PO4)3]—has been obtained under hydrothermal conditions. Its crystal structure was determined by single crystal X-ray diffraction: space group P6ccP6cc, Z=4Z=4, a=13.765(1)a=13.765(1), c=9.4753(7) Åc=9.4753(7) Å at 293 K, wR2=0.068wR2=0.068, R=0.030R=0.030. In the structure [VO5] polyhedra form six-membered rings by sharing vertices. Each two neighboring V polyhedra in the ring are additionally bridged by [PO4] tetrahedra. All vanadyl groups (O6) remain terminal and are pointing toward the c  -direction giving rise to a strongly polar structure. Ti octahedra link these V, P rings by sharing all six vertices with P tetrahedra under formation of a three-dimensional anionic framework [Ti(VO2)3(PO4)3]2−∞∞∞. Intersecting channels in the [001], [100], [010], and [110] directions, containing the Cs cations suggest to consider the new compound as a possible 3D ion-conductor. Topological relations between this new structure and the mineral benitoit BaTiSi3O9 are discussed.

A new third modification of manganese(II) orthophosphate Mn3(PO4)2 has been obtained under hydrothermal conditions. Its crystal structure was determined by single crystal X-ray diffraction: space group P21/nP21/n, Z=2Z=2, a=5.2344(5)a=5.2344(5), b=6.6739(7)b=6.6739(7), c=8.9688(10)Å, β=95.276(9)°β=95.276(9)° at 293 K, wR2=0.050wR2=0.050, R=0.019R=0.019. In the structure, [MnO5] polyhedra and [MnO6] octahedra in a ratio of 2:1 share common edges to form chains alternating along the [110] and [1¯10] directions. They are further linked by common vertices and the phosphate tetrahedra to a 3D framework. The relations of this new structure type to the other polymorphs of Mn3(PO4)2 and related Mn and Fe phosphates are discussed.

The title compound has been prepared by hydrothermal synthesis and its crystal structure was determined by single crystal X-ray diffraction: space group I4/mmm, a=6.3856(2), c=10.6119(9) Å, wR2=0.039, R=0.016. The crystal structure of Na3{V2O2F[PO4]2} is formed by layers of alternating [VO5F] octahedra and [PO4] tetrahedra sharing O vertices parallel to the ab plane. Along the c direction the V octahedra are joined pairwise through common F vertices in the inversion centres. The sixth O vertex of the V octahedron is the terminal oxo ligand of a vanadyl group. Thus, the structure is described by a mixed paraframework of octahedra and tetrahedra {V2O2F[PO4]2}∞∞∞ with disordered Na atoms in the interstices. The new phase is discussed as a member in the row of compounds structurally related to the mineral natisite and VOPO4·2H2O.Graphic

4,4′-bipyMnF3 (bipy=bipyridine) has been crystallized from the system MnIII/4,4′-bipy/HF/H2O/methanol/acetone and its crystal structure was determined by single crystal X-ray diffraction at different temperatures: at 295 K the structure is orthorhombic, space group I222, Z=2, a=10.704(1),b=11.384(2) Å, c=3.9413(4) Å, wR2=0.0637, R=0.0244. MnIII is octahedrally coordinated by four F and two N ligands. In the c direction an inorganic FMnFMn– trans-chain is formed, along the b axis bridging by the organic bipy ligands takes place, thus the structure can be classified as a 2D hybrid coordination polymer. The 180° MnFMn bridge angle is symmetry imposed but large anisotropic displacement ellipsoids for the F ligands indicate dynamical disorder of an angular chain. At 240 K and 153 K 1D incommensurate modulated structures (space group I222(00γ)00s) are observed with large variation of the bridge angle down to 149°. Below 100 K the structure can be described as “lock-in phase” with doubled c-axis in the orthorhombic space group P212121 and a bridge angle of 156.4°. 4,4′-bipyMnF3 shows 1D antiferromagnetic properties with an exchange energy along the MnFMn chain of J/k=−11.5 K.Graphic

The title compound has been prepared by a flux crystallisation method and its crystal structure was determined by single crystal X-ray diffraction: space group P, a=5.309(1), b=7.133(1), c=14.746(2) Å, α=99.05(1), β=95.97(1), γ=90.08(1)°, wR2=0.073, R=0.028. The structure may be described as built by seidozerite modules of composition Na2Ti2O2Si2O7 — brucite-type layers of [TiO6] and [NaO6] octahedra embedded between layers of [TiO6] octahedra, [Si2O7] groups and [NaO8] polyhedra. These almost centrosymmetrical triple-layers alternate along the c-axis with polar double-layer-modules of composition Na3VO4 formed by isolated [VO4]3− anions and six- and four-coordinate Na cations. The crystal structure is discussed in context with minerals of the lomonosovite group. The thermal decomposition behaviour suggests a decay to the single modular components Na2Ti2O2Si2O7 and Na3VO4.