Hydrothermal synthesis, structure and antiferromagnetism of Mn[P2O5(OH)2]

A new manganese diphosphate Mn[P2O5(OH)2] (1) has been hydrothermally synthesized and structurally characterized by single-crystal X-ray diffraction. It crystallizes in the monoclinic space group C2/c with the lattice: a = 7.1487(14) Å, b = 7.9804(16) Å, c = 9.4812(19) Å, β = 101.18(3)°, V = 530.63(18) Å3, and Z = 4. Mn2+ is coordinated in a typical octahedral environment and the phosphates are dimerized as P2O7 groups. Each MnO6 is surrounded by six PO4 and each PO4 group (as a part of P2O7) is linked with three MnO6, giving an Mn:P ratio of 1:2. Upon heating, the 3D structure of 1 keeps intact until the dehydration, which occurs at 390 °C and leads to a known phase Mn2P4O12. The magnetic interactions between Mn2+ ions transmitted via O–P–O are antiferromagnetic (AFM) and 1 shows an AFM long-range ordering at 3.5 K.

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