A Redox‐Triggered Structural Rearrangement in an Iodate‐Templated Polyoxotungstate Cluster Cage.

(TEAH)5Na [H5W18O59(IO3)] ·5H2O (I; TEAH: (HO-CH2-CH2)3NH+), the first example of a polyoxometalate with encapsulated IO3-, is synthesized from an aqueous solution of Na2WO4, H5IO6, and TEAHCl (pH 1.3 adjusted with 6M HCl, reflux, 1 h; yield given in g).