Two rare Cr-Ln (Ln = Dy, Tb) heterometallic cluster substituted polyoxometalates featuring hexameric aggregates: hydrothermal syntheses, crystal structures and magnetic studies

Two hexameric chromium-lanthanide heterometallic cluster substituted polyoxometalates (POMs), K9Na14Cs12H[Cr6Dy6(H2O)(12)(alpha-GeW10O38)(6)]center dot 33H(2)O (1-Dy) and K9Na14Cs12H[Cr6Tb6(H2O)(12)(alpha-GeW10O38)(6)]center dot 65H(2)O (1-Tb), have been hydrothermally synthesized and structurally characterized through single-crystal X-ray diffraction analysis, powder X-ray diffraction analysis, thermogravimetric analysis, infrared spectroscopy and solid-state ultraviolet-visible spectroscopy. Compounds 1-Dy and 1-Tb represent the first examples of 3d-4f heterometallic cluster substituted POMs incorporating chromium-lanthanide clusters. What's more, magnetic investigations indicate that overall antiferromagnetic coupling is present in 1-Dy and 1-Tb.