ABSTRACT The controlled assembly of giant polyoxometalates (POMs) remains a significant challenge in inorganic chemistry. Herein, we demonstrate that rare‐earth ions can direct distinct structural outcomes in nickel‐substituted tungstate systems. Hydrothermal reaction of the flexible precursor B‐ α ‐SbW 9 O 33 with KH 2 PO 4, Er 2 O 3, and NiCl 2 yielded a giant all‐inorganic cluster W 88 Ni 39 (1), adopting an unprecedented “Teddy‐Bear”‐like architecture. Under identical conditions, omission of Er 2 O 3 (or replacement with Dy 2 O 3) afforded the smaller cluster W 55 Ni 17 (2), corresponding to the “head” of the “Teddy‐Bear”. Notably, Dy 2 O 3 improves the crystallization yield of W 55 Ni 17 relative to the rare‐earth‐free reaction. Remarkably, replacing Er 2 O 3 with Gd 2 O 3 afforded a giant tetramer W 140 Gd 10 Ni 48 (3), whose monomer is analogous to the W 33 Ni 21 “Teddy‐Bear body” motif in W 88 Ni 39. These clusters rank among the largest discrete tungsten‐based POM assemblies known. Importantly, the crystallization of W 88 Ni 39 and W 140 Gd 10 Ni 48 enables an efficient organic‐free separation of the rare‐earth oxides Er 2 O 3 and Gd 2 O 3 with a separation factor of 360. 37, revealing a new strategy based on structure‐directed hierarchical assembly for selective crystallization in rare‐earth‐mediated POM systems.
Li et al. (Wed,) studied this question.