Extreme Differences in Oxidation States: Synthesis and Structural Analysis of the Germanide Oxometallates A₁₀[Ge₉]₂[WO₄] As Well As A_10+<i>x</i>[Ge₉]₂[W_1–<i>x</i>Nb_<i>x</i>O₄] with A = K and Rb Containing [Ge₉]^4– Polyanions

Semitransparent dark-red or ruby-red moisture- and air-sensitive single crystals of A_10+<i>x</i>[Ge₉]₂[W_1–<i>x</i>Nb_<i>x</i>O₄] (A = K, Rb; <i>x</i> = 0, 0.35) were obtained by high-temperature solid-state reactions. The crystal structure of the compounds was determined by single-crystal X-ray diffraction experiments. They crystallize in a new structure type (<i>P</i>2₁<i>/c</i>, <i>Z</i> = 4) with <i>a</i> = 13.908(1) Å, <i>b</i> = 15.909(1) Å, <i>c</i> = 17.383(1) Å, and β = 90.050(6)° for K_10.35(1)[Ge₉]₂[W_0.65(1)Nb_0.35(1)O₄]; <i>a</i> = 14.361(3) Å, <i>b</i> = 16.356(3) Å, <i>c</i> = 17.839(4) Å, and β = 90.01(3)° for Rb_10.35(1)[Ge₉]₂[W_0.65(1)Nb_0.35(1)O₄]; <i>a</i> = 13.8979(2) Å, <i>b</i> = 15.5390(3) Å, <i>c</i> = 17.4007(3) Å, and β = 90.188(1)° for K₁₀[Ge₉]₂WO₄; and <i>a</i> = 14.3230(7) Å, <i>b</i> = 15.9060(9) Å, <i>c</i> = 17.8634(9) Å, and β = 90.078(4)° for Rb₁₀[Ge₉]₂WO₄. The compounds contain discrete Ge₉^4– Wade’s <i>nido</i> clusters and WO₄^2– (or NbO₄^3–) anions, which are packed according to a hierarchical atom-to-cluster replacement of the Al₂Cu prototype and are separated by K and Rb cations, respectively. The alkali metal atoms occupy the corresponding tetrahedral sites of the Al₂Cu prototype. The amount of the alkali metal atoms on these diamagnetic compounds corresponds directly to the amount of W substituted by Nb. Thus, the transition metals W and Nb appear with oxidation numbers +6 and +5, respectively, in the vicinity of a [Ge₉]^4– polyanion. The crystals of the mixed salts were further characterized by Raman spectroscopy. The Raman data are in good agreement with the results from the X-ray structural analyses

Extreme Differences in Oxidation States: Synthesis and Structural Analysis of the Germanide Oxometallates A₁₀[Ge₉]₂[WO₄] As Well As A_10+<i>x</i>[Ge₉]₂[W_1–<i>x</i>Nb_<i>x</i>O₄] with A = K and Rb Containing [Ge₉]^4– Polyanions

Semitransparent dark-red or ruby-red moisture- and air-sensitive single crystals of A_10+<i>x</i>[Ge₉]₂[W_1–<i>x</i>Nb_<i>x</i>O₄] (A = K, Rb; <i>x</i> = 0, 0.35) were obtained by high-temperature solid-state reactions. The crystal structure of the compounds was determined by single-crystal X-ray diffraction experiments. They crystallize in a new structure type (<i>P</i>2₁<i>/c</i>, <i>Z</i> = 4) with <i>a</i> = 13.908(1) Å, <i>b</i> = 15.909(1) Å, <i>c</i> = 17.383(1) Å, and β = 90.050(6)° for K_10.35(1)[Ge₉]₂[W_0.65(1)Nb_0.35(1)O₄]; <i>a</i> = 14.361(3) Å, <i>b</i> = 16.356(3) Å, <i>c</i> = 17.839(4) Å, and β = 90.01(3)° for Rb_10.35(1)[Ge₉]₂[W_0.65(1)Nb_0.35(1)O₄]; <i>a</i> = 13.8979(2) Å, <i>b</i> = 15.5390(3) Å, <i>c</i> = 17.4007(3) Å, and β = 90.188(1)° for K₁₀[Ge₉]₂WO₄; and <i>a</i> = 14.3230(7) Å, <i>b</i> = 15.9060(9) Å, <i>c</i> = 17.8634(9) Å, and β = 90.078(4)° for Rb₁₀[Ge₉]₂WO₄. The compounds contain discrete Ge₉^4– Wade’s <i>nido</i> clusters and WO₄^2– (or NbO₄^3–) anions, which are packed according to a hierarchical atom-to-cluster replacement of the Al₂Cu prototype and are separated by K and Rb cations, respectively. The alkali metal atoms occupy the corresponding tetrahedral sites of the Al₂Cu prototype. The amount of the alkali metal atoms on these diamagnetic compounds corresponds directly to the amount of W substituted by Nb. Thus, the transition metals W and Nb appear with oxidation numbers +6 and +5, respectively, in the vicinity of a [Ge₉]^4– polyanion. The crystals of the mixed salts were further characterized by Raman spectroscopy. The Raman data are in good agreement with the results from the X-ray structural analyses