A Cagelike Polyanion with a Ag⁺ Enwrapped, [AgAs₂Mo₁₅O₅₄]¹¹⁻

The polyanion [AgAs2Mo15O54]11− has an unusual cage-like structure composed of [AsMo6O27]15− and [AsMo6O24]9− subunits connected by three MoO4 tetrahedra, and a Ag+ cation is inclosed at the center of the cage and coordinated by two As atoms with a As−Ag−As bond angle of 180° along with three μ3-oxo groups from MoO4 tetrahedra to lead to a trigonal-pyramidal coordination geometry. The compound was also characterized by IR, X-ray photoelectron spectroscopy, fluorescent spectroscopy, and thermogravimetry-differential scanning calorimetry. The stability of [AgAs2Mo15O54]11− in aqueous solution was investigated by using electronic absorbance spectroscopy and electrospray ionization mass spectrometry.