Reverse-Keggin Ions: Polycondensation of Antimonate Ligands Give Inorganic Cryptand

Reverse-Keggin ions are reported in which a p-block element (antimony) occupies the twelve vertices of a truncated tetrahedron while a d-block element (manganese or zinc) occupies the tetrahedral central cavity. The exterior of the reverse-Keggins also acts as tridentate ligands to further d-block centers.