A novel sandwich polyoxometalate linked by mixed RE/TM interlayer: [Fe(phen)3]2[As2W18Fe2{Y(OH2)2}2O68]·6.5H2O

A novel sandwich polyoxometalate, [Fe(phen)3]2[As2W18Fe2{Y(H2O)2}2O68]·6. 5H2O 1, (phen = 1,10-phenanthroline), has been hydrothermally synthesized and characterized by elemental analyses, IR(25 ∼ 650 °C), single-crystal X-ray diffraction, ESR spectroscopy and thermal analyses (TG-DTA). The crystallographic analysis reveals that the dimeric polyanion, [As2W18Fe2{Y(OH2)2}2O68]6−, are constructed from two [B-AsW9O34]9− fragments linked by two Y3+ ions and two Fe3+ ions. The ESR spectra exhibit that the high spin state and the low spin state of Fe(III) coexist in the title compound.