Ln₁₂-Containing 60-Tungstogermanates: Synthesis, Structure, Luminescence, and Magnetic Studies

A new class of hexameric Ln₁₂-containing 60-tungstogermanates, [Na(H₂O)₆⊂Eu₁₂(OH)₁₂(H₂O)₁₈Ge₂(GeW₁₀O₃₈)₆]^39- (Eu₁₂), [Na(H₂O)₆⊂Gd₁₂(OH)₆(H₂O)₂₄Ge(GeW₁₀O₃₈)₆]^37- (Gd₁₂), and [(H₂O)₆⊂Dy₁₂(H₂O)₂₄(GeW₁₀O₃₈)₆]^36- (Dy₁₂), comprising six di-Ln-embedded {β(4,11)-GeW₁₀} subunits was prepared by reaction of [α-GeW₉O₃₄]^10- with Ln^III ions in weakly acidic (pH 5) aqueous medium. Depending on the size of the Ln^III ion, the assemblies feature selective capture of two (for Eu₁₂), one (for Gd₁₂), or zero (for Dy₁₂) extra Ge^IV ions. The selective encapsulation of a cationic sodium hexaaqua complex [Na(H₂O)₆]⁺ was observed for Eu₁₂ and Gd₁₂, whereas Dy₁₂ incorporates a neutral, distorted-octahedral (H₂O)₆ cluster. The three compounds were characterized by single-crystal XRD, ESI-MS, photoluminescence, and magnetic studies. Dy₁₂ was shown to be a single-molecule magnet. Cagelike polyoxometalates: A new class of cagelike Ln₁₂-containing 60-tungstogermanates (Ln=Eu, Gd, Dy) was prepared by the reaction of [α-GeW₉O₃₄]^10- with Ln^III ions in a weakly acidic aqueous medium. Depending on the size of the Ln^III ion, the assemblies feature selective capture of two (Eu₁₂), one (Gd₁₂), or zero (Dy₁₂) extra Ge^IV ions. Selective encapsulation of [Na(H₂O)₆]⁺ was observed for Eu₁₂ and Gd₁₂, whereas Dy₁₂ incorporates a neutral, distorted-octahedral (H₂O)₆ cluster (see figure).