Record High‐Nuclearity Polyoxoniobates: Discrete Nanoclusters {Nb 114 }, {Nb 81 }, and {Nb 52 }, and Extended Frameworks Based on {Cu 3 Nb 78 } and {Cu 4 Nb 78 }

A series containing the highest nuclearity polyoxoniobate (PONb) nanoclusters, ranging from dimers to tetramers, has been obtained. They include one 114‐nuclear {Li 8 ⊂Nb 114 O 316 }, one 81‐nuclear {Li 3 K⊂Nb 81 O 225 }, and one 52‐nuclear {H 4 Nb 52 O 150 }. The Nb nuclearity of these PONbs is remarkably larger than those of all known high‐nuclearity PONbs (≤32). Furthermore, the introduction of 3d Cu 2+ ions can lead to the generation of extended inorganic–organic hybrid frameworks built from novel, high‐nuclearity, nanoscale heterometallic PONb building blocks {H 3 Cu 3 Nb 78 O 222 } or {H 3 Cu 4 (en)Nb 78 O 222 }. These building blocks also contain the largest number of Nb centers of any heterometallic PONbs reported to date. The synthesis of new‐type PONbs has long been a challenging subject in PONb chemistry.