Organic-inorganic hybrid materials of the copper molybdate family. Syntheses and structures of [Cu(tpa)Mo₂O₇], [Cu(Me ₂bpy)Mo₂O₇]

The hydrothermal reactions of CuSO₄ · 5H₂O and MoO₃ in the presence of various sterically hindered polypyridyl ligands have been studied. Under basic conditions, [Cu(tpa)Mo₂O ₇](1) and [Cu(Me₂bpy)Mo₂O₇](2) are formed, while under mildly acidic conditions, [Cu(t-Bu₂bpy)Mo ₄O₁₃](4) is the product. The structures of 1 and 2 are grossly similar in that both are constructed from molybdate chains decorated with secondary metal-ligand coordination cation subunits. In the case of 1, the molybdate chain consists of alternating pairs of edge-sharing octahedra and square pyramids, while for 2, the chain exhibits corner-sharing octahedra with peripheral tetrahedral sites. The profound structural influences of hydrothermal reaction conditions such as pH are dramatically illustrated by the structure of 4 which consists of octamolybdate clusters linked through binuclear {Cu₂(t-Bu₂bpy)₂}⁴⁺ sites.