Al16-hydroxide Cluster-containing Tetrameric Polyoxometalate, [{α-Al3SiW9O34(µ-OH)6}4{Al4(µ-OH)6}]22−

Abstract A novel Al16-hydroxide cluster-containing polyoxometalate tetramer, [{α-Al3SiW9O34(µ-OH)6}4{Al4(µ-OH)6}]22− (Al16-tetramer), was obtained as a potassium salt and characterized by single-crystal X-ray diffraction, FTIR, elemental analysis, TG/DTA, and (29Si, 183W) NMR. The Al16-tetramer adopts a nanosized structure containing an Al16-hydroxide cluster, and maintains its structure in solution. Therefore, the Al16-tetramer is a model compound for aluminum-containing clusters.