New Perspectives for Old Clusters: Anderson–Evans Anions as Building Blocks of Large Polyoxometalate Frameworks in a Series of Heterometallic 3 d–4 f Species

A series of nine [Sb 7 W 36 O 133 Ln 3 M 2 (OAc)(H 2 O) 8 ] 17− heterometallic anions ( Ln 3 M 2 ; Ln=La–Gd, M=Co; Ln=Ce, M=Ni and Zn) have been obtained by reacting 3 d metal disubstituted Krebs‐type tungstoantimonates(III) with early lanthanides. Their unique tetrameric structure contains a novel {MW 9 O 33 } capping unit formed by a planar {MW 6 O 24 } fragment to which three {WO 2 } groups are condensed to form a tungstate skeleton identical to that of a hypothetical trilacunary derivative of the ɛ‐Keggin cluster. It is shown, for the first time, that classical Anderson–Evans {MW 6 O 24 } anions can act as building blocks to construct purely inorganic large frameworks. Unprecedented reactivity in the outer ring of these disk‐shaped species is also revealed. The Ln 3 M 2 anions possess chirality owing to a {Sb 4 O 4 } cluster being encapsulated in left‐ or right‐handed orientations. Their ability to self‐associate in blackberry‐type vesicles in solution has been assessed for the Ce 3 Co 2 derivative.