Combination of Lacunary Polyoxometalates and High-Nuclear Transition Metal Clusters under Hydrothermal Conditions. 3. Structure and Characterization of [Cu(enMe)₂]₂{[Cu(enMe)₂(H₂O)]₂[Cu₆(enMe)₂(<i>B</i>-<i>a</i>-SiW₉O₃₄)₂]}·4H₂O

A novel sandwich-type polyoxometalate incorporating a unique hybrid hexanuclear copper cluster, [Cu(enMe)2]2{[Cu(enMe)2(H2O)]2[Cu6(enMe)2(B-a-SiW9O34)2]}·4H2O (1, enMe = 1,2-diaminopropane), has been hydrothermally
synthesized and structurally characterized by the elemental analyses, IR spectroscopy, TG analysis, magnetic
properties, and single-crystal X-ray diffraction analysis. Crystal data for 1: triclinic, P1̄; a = 12.5105(2), b = 14.3710(2), c = 17.2687(2) Å; α = 98.834(1), β = 110.744(1), γ = 104.711(1)°; V = 2704.57(7) Å3; ρ = 3.646 g/cm3;
Z = 1. X-ray crystallographic study shows that the molecular structure of 1 contains 10 copper ions:  Six of them
form an unprecedented inorganic−organic hybrid Cu6 cluster via edge-sharing combination of two CuO6 octahedra,
two CuO5, and two CuO3N2 square pyramids and are encapsulated between two {B-a-SiW9O34} units. Two of
them form two [Cu(enMe)2(H2O)]2+ complexes and further attach to the two {B-a-SiW9O34} units via two Cu−OW bridges, acting as a decorated role. The remaining two form isolated [Cu(enMe)2]2+ complexes playing roles of
charge-compensation and space-fillers. Magnetization measurement reveals that the hexanuclear copper cluster
exhibits overall ferromagnetic interactions.