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) (.) 4H(2)O, MoO3, tetra-4-pyridylpyrazine, H2O3PCH3, and HF at 200degreesC for 96 h yields orange crystals of [Ni(tpyrpyz)(2)](2)[Mo4O12F2][Mo6O17] (.) 2H(2)O (1 (.) 2H(2)O). 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 mu(2)-O, O' bridging mode. (C) 2003 Elsevier B.V. All rights reserved.