Solvothermal Treatment of Triangular Molybdenum(IV) Oxo Species - A New Approach for the Synthesis of New Molybdenum Oxo Clusters

An unprecedented solvothermal treatment of triangular molybdenum oxo clusters K(2)[Mo(3)O(4)(Hnta)(3)] (1, nta = nitrilotriacetate) and H(2)bipy[Mo(3)O(4)(C(2)O(4))(3)(H(2)O)(3)] (2, bipy = 4,4'-bipyridine) was successfully established to prepare a series of new oligonuclear Mo(IV-VI) oxo clusters 3-5. Hydrothermal treatment of 1 in aqueous solution produced the hexanuclear cluster [Mo(6)(IV)O(10)(bpy)(4)(Hnta)(2)]center dot 10H(2)O (3, bpy = 2,2'-bipyridine). Solvothermal oxidation of 2 was performed in pyridine (py) to yield the unprecedented decanuclear mixed-valent oxo cluster [Mo(6)(IV)Mo(4)(VI)O(24)py(8)]center dot py (4). The further oxidized product [Mo(8)(V)Mo(2)(VI)O(26)py(8)]center dot 2py (5) was obtained from a reaction at a higher temperature and for a longer duration. Clusters 3-5 have been characterized by X-ray crystallography, elemental analysis, and UV/VIS and IR spectroscopy.