Synergistic Bimetallic Active Sites in Extended MOF‐74 Architectures for Highly Efficient Oxidative Carboxylation of Olefins with CO₂

In this work, a series of ligand‐extension MOF‐74‐type frameworks M 2 (hob) (M = tunable Mn/Zn, hob 4‐ = 5,5′‐(hydrazine‐1,2‐diylidenebis(methanylylidene))bis(2‐oxidobenzoate)) materials is synthesized for the direct oxidative carboxylation of alkenes with CO 2 . Structural expansion affords enlarged pores and enhanced surface area, facilitating substrate diffusion. Comprehensive characterization confirms that Mn 1 Zn 2 (hob) exhibits optimal structural integrity, morphological uniformity, enhanced textural properties, and maximal Mn 3+ active species concentration. The results show that Mn 1 Zn 2 (hob) exhibits optimal performance in the solvent‐free reaction system with styrene (9 mmol), tert‐butyl hydroperoxide (13.5 mmol), and tetrabutylammonium bromide (TBAB, 50 mg) at 80 °C under 1.5 MPa CO 2 for 5 h, achieving a styrene conversion of 94.1% and styrene carbonate (SC) selectivity of 55.5%. The superior activity originates from synergistic interactions among bimetallic Lewis‐acid sites (Mn/Zn), weak basic sites of metal−O units, and redox‐active Mn III centers. The catalyst also demonstrates broad substrate generality and stable recyclability (>6 cycles), with a mechanistic proposal for direct olefin oxidative carboxylation to cyclic carbonates.