Bulky α-Diimine Palladium-Based Hyper-Cross-Linked Polymers: Highly Efficient Porous Catalysts for Direct C–H Heteroarylation

To overcome the synthetic complexity and poor stability associated with conventional Pd-based heterogeneous catalysts, we describe a structurally rigid α-diimine palladium complex that acts as both the catalytic precursor and the cross-linkable monomer in a self-polycondensation approach. The resulting hyper-cross-linked polymer, DIMAQ-Pd-HCP, is prepared without external cross-linkers or metal catalysis. Its rigid acenaphthenequinone backbone and multiaryl substituents confer excellent thermal stability and suppress CAr–N rotation, stabilizing the Pd(II) species. The catalyst exhibits high efficiency in direct C–H arylation of heteroarenes with heteroaryl bromides under aerobic conditions, achieving excellent yields at ultralow Pd loadings (0.15 mol %). Control experiments confirm the truly heterogeneous nature and good recyclability of the catalyst. This work offers a ligand-driven and scalable platform for constructing robust solid-state Pd catalysts for sustainable C–H functionalization.