Trimeric, cyclic Ti10-containing 27-tungsto-3-germanate [(α-Ti3GeW9O37OH)3(TiO3(OH2)3)]17−

The trimeric, cyclic polyanion [(α-Ti3GeW9O37OH)3(TiO3(OH2)3)]17− (Ti10) was synthesized by reaction of [A-α-GeW9O34]10− with K8[Ti4O4(C2O4)8] in a mixture of rubidium and lithium acetate buffers at 60 °C, and then crystallized as a mixed rubidium-potassium-sodium salt, Rb13K2Na2[(α-Ti3GeW9O37OH)3(TiO3(OH2)3)]·40H2O (Rb-Ti10). The title compound was characterized in the solid state by IR, single-crystal XRD, TGA and elemental analysis, and in solution by 183W-NMR. In order to prepare a pure sample of Rb-Ti10, several reaction parameters need to be carefully controlled, such as the ratio of rubidium and lithium acetate buffers, the choice of titanium precursor (K8[Ti4O4(C2O4)8]), the reaction temperature, and very importantly, the concentration of rubidium ions.