Syntheses and structures of two copper-molybdate complexes: The 3-D [Cu(4,4′-bpy)(MoO4)] and 1-D [Cu2(HDABCO)2(H2Mo8O27)] · 4H2O

Hydrothermal reaction of molybdenum oxide and copper(II) source in the presence of 4,4′-bipyridine (4,4′-bpy) afforded three-dimensional covalent framework Cu^II(4,4′-bpy)(MoO₄)] (1), while reaction with 1,4-diazoniabicyclo2,2,2]octane (DABCO) in place of 4,4′-bpy and addition of metal molybdenum resulted in one-dimensional chain-like compound . The copper in 1 is divalent and approximately shows trigonal bipyramidal geometry, while in 2 is monovalent and approximately shows T-shaped geometry. The structure of 1 has a three-dimensional pillar-layered framework constructed from bimetallic {CuMoO₄} layers bridged by bifunctional ligand 4,4′-bpy. Interestingly, the {CuMoO₄} layer in 1 consists of 16-membered {Cu₄Mo₄O₈} rings and 8-membered {Cu₂Mo₂O₄} rings, different from other reported {CuMoO₄} layers. The structure of 2 consists a one-dimensional chain that is attached by peripheral {Cu(HDABCO)}²⁺ units. The chain is constructed from octamolybdates through common corners.