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, DIM AQ -Pd-HCP, is prepared without external cross-linkers or metal catalysis. Its rigid acenaphthenequinone backbone and multiaryl substituents confer excellent thermal stability and suppress C Ar –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.