A Bismuth-Incorporated Telluroniobate with a Crown-Like {Bi3Te3} Heterometal-Oxo Ring: Structure and Photocatalytic Aerobic Ipso-Hydroxylation of Organoboronic Acids.

A novel inorganic-organic hybrid bismuth-incorporated telluroniobate, H[Cu(H2O)(en)2]6[BiIII3(H2O)6TeIV5Nb18O66]·24H2O (1, en = ethylenediamine), is built from a unique peanut-shaped sandwich-type {BiIII3(H2O)6TeIV5Nb18O66} ({Bi3Te5Nb18}) polyanion and [Cu(en)2(H2O)]2+ complex cations. Notably, the {Bi3Te5Nb18} cluster represents the first heteropolyoxoniobate incorporating Bi-Te dual-heteroatoms, wherein the central {Bi3Te3} ring cluster is symmetrically sandwiched between two α-Keggin-type {TeNb9} building blocks. Robust intermolecular N-H···O hydrogen bonds further link the {Bi3Te5Nb18} polyoxoanions and copper-amine complexes into a 3D supramolecular framework with acs topology. Benefiting from its good structural stability, compound 1 serves as an efficient heterogeneous photocatalyst for the aerobic ipso-hydroxylation of organoboronic acids under mild conditions, affording the corresponding phenols in yields as high as 93%. Additionally, compound 1 exhibits a broad substrate scope, good recyclability, and scalability to gram-scale reaction. This work offers a novel insight for the rational design and synthesis of structurally well-defined, function-targeted heteropolyoxoniobate-based photocatalytic materials.