Syntheses and crystal structures of the manganese hydroxide halides Mn5(OH)6Cl4, Mn5(OH)7I3, and Mn7(OH)10I4

Single-crystals of the new manganese hydroxide halides Mn5(OH)6Cl4, Mn5(OH)7I3, and Mn7(OH)10I4 were obtained by means of high-pressure/high-temperature synthesis in a Walker-type multianvil apparatus. The chloride crystallizes in the monoclinic space group P21/c (no. 14) with the lattice parameters (single-crystal data) a = 592.55(8), b = 1699.7(2), c = 597.33(8) pm, and β = 112.58(1)°. The iodides crystallize in the triclinic space group P 1 ‾ $\bar{1}$ (no. 2) with a = 653.16(2), b = 905.98(3), c = 1242.98(4) pm, α = 114.21(1)°, β = 99.91(1)°, and γ = 94.37(1)° for Mn5(OH)7I3 and a = 656.90(3), b = 906.59(4), c = 909.32(4) pm, α = 119.29(1)°, β = 97.99(1)°, and γ = 95.03(1)° for Mn7(OH)10I4. The crystal structures consist of edge-sharing Mn(OH)6–n X n (X = Cl, I; n = 1, 2, 3) octahedra arranged in stacked sheets. Adjacent layers are connected by hydrogen bonds of type O–H···X, confirmed by further characterization of single-crystals by IR-spectroscopy. The crystal chemical relationship with the aristotype Mg(OH)2 (brucite) is discussed on the basis of Bärnighausen trees (group–subgroup relations).