An interesting fourfold interpenetrating network constructed by polyoxometalates and metal–organic coordination complexes:

A novel fourfold interpenetrating 3D network compound, [ Cu I 5 ( bpy ) 5 ( H 2 O ) 2 ] [ [ Cu II ( H 2 O ) 3 ] 2 Cu II [ P 4 Mo V 6 O 25 ( OH ) 6 ] 2 ] · H 3 O + · 2 H 2 O 1 (bpy = 4,4′-bipyridine), has been synthesized and characterized by elemental analyses, IR, TG analyses, and single-crystal X-ray diffraction. Compound 1 is built up of Cu[P4Mo6O25(OH)6]2 clusters covalently linked by Cu-bpy coordination polymer chains to yield unusual two-dimensional layers, which are further connected together by metal coppers to produce an interesting fourfold interpenetrating 3D network structure. The crystal data for compounds 1: Triclinic, space group P 1 ¯ , a = 12.714(3) Å, b = 14.882(3) Å, c = 15.369(3) Å, α = 72.74(3)°, β = 72.12(3)°, γ = 65.62(3)°, V = 2471.9(9) Å3, Z = 1.