A new organic-inorganic hybrid polyoxometalate based on Dawson-like polyoxotungstate anion [SbW18O60]9, formulated [Co(2,2′-bpy)3]2[Co(2,2′-bpy)2Cl][Co(2,2′-bpy)2]H2[SbW18O60]·4H2O (2,2′-bpy= 2,2′-bipyridine) has been synthesized from Sb2O3, Na2WO4, CoCl2, and 2,2′-bipyridine materials by hydrothermal method, and which was characterized by elemental analyses, IR, XPS, EPR, TG, and X-ray single crystal diffraction. Structure analysis shows that the polyoxoanion self-assembled under hydrothermal conditions consists of a Dawson-like polyoxotungstate cluster anion [SbW18O60]9 en- capsulating a pyramidal {SbO3} group within the {W18} cluster cage. EPR spectra show that the high-spin octahedral CoII and low-spin CoII ions coexist in the title compound. Magnetic properties in- dicate that the compound is antiferromagnetic.
