Hydrothermal synthesis and structure of [Ni(tpyrpyz)2]2[Mo4O12F2][Mo6O19] · 2H2O, a material exhibiting an unusual tetranuclear polyoxofluoromolybdate cluster [Mo4O12F2]2−

The hydrothermal reaction of a solution of Ni(CH3CO2)2 · 4H2O, MoO3, tetra-4-pyridylpyrazine, H2O3PCH3, and HF at 200 °C for 96 h yields orange crystals of [Ni(tpyrpyz)2]2[Mo4O12F2][Mo6O17] · 2H2O (1 · 2H2O). The structure consists of discrete {Ni(tpyrpyz)2}2+ cations and {Mo6O19}2− and {Mo4O12F2}2− anionic clusters. The hexamolybdate is the well-documented octahedron of octahedra, that is, six {MoO6} octahedra in a compact edge-sharing arrangement. The novel oxyfluoride cluster {Mo4O12F2}2− features two {MoO4F2} octahedra, sharing the edge defined by the fluoride ligands; the octahedral Mo sites corner-share to two {MoO4} tetrahedra in the μ2–O, O′ bridging mode.