A Giant Ce3+-Bridged Selenotungstate Containing Three Different Building Blocks for Photocatalyzed C–N Bonds Formation

The quest to delve into high-nuclearity molecular metal-oxo clusters and unravel their reactivity presents a significant challenge in chemistry and materials science. In this work, we synthesized an unprecedented bowknot-like selenotungstates, [Ce₇Se₇W₄₇O₁₇₁(OH)(H₂O)₂₅(mal)]₂^30- (Ce₁₄W₉₄, H₃mal = dl-malic acid) via an in situ assembly strategy. The three building units, including tetravacant Keggin-{SeW₈}, bivacant Dawson-{Se₂W₁₆}, and trivacant Keggin-{SeW₉}, were self-assembled by the connection of {W₁}, independent {SeO₃} fragments, and seven mutually isolated Ce³⁺ ions to form the unique asymmetric structure, which was further extended to the bowknot-like dimeric structure and the 1D chain structure by symmetry. Due to the good photoelectric activity, Ce₁₄W₉₄ can serve as a highly efficient photocatalyst for the conversion of C-H to C-N bonds by hydroacylation of dialkyl azodicarboxylates, with a broad substrate scope and excellent reusability. This work enriches the assembly mode of POMs and provides a highly efficient photocatalyst.