Capture of Periodate in a {W18O54} Cluster Cage Yielding a Catalytically Active Polyoxometalate [H3W18O56(IO6)]6− Embedded with High‐Valent Iodine

Periodate in the mix: The first crystallographically characterized tungstatoperiodate cluster of the form β*-[H3W18O56(IO6)]6−, with periodate embedded inside a {W18O54} cluster cage, remains intact in solution, and is the first in a new class of [HnW18O56(XO6)]m− heteropolyoxotungstates. Mass spectrometry, and electrochemical and catalytic studies, verified by DFT calculations, reveal its unusual physical properties.