Ligand‐Induced Effect on CO ₂ /C ₂ H ₄ Coupling Using Nickel/Palladium‐Based Catalyst

ABSTRACT Bisphosphine‐based transition metal complexes have emerged as promising catalysts for the coupling of CO 2 and ethylene to synthesize acrylic acid, a reaction of significant industrial and environmental interest. This study investigates how systematic variation of bisphosphine ligands perturbs catalytic performance through a combined density functional theory (DFT) and experimental approach. Computational analysis reveals that CO 2 and ethylene undergo oxidative coupling over Ni/Pd bisphosphine catalysts to form a key metallalactone (2), which subsequently diverges along three distinct reaction pathways: (a) reductive elimination to yield a lactone byproduct, (b) ring opening via β‐hydride transfer to the metal centre, and (c) ring opening through enolization. Building on prior work that identified a Lewis acid/base‐assisted keto‐enol tautomerization as a viable mechanistic route with enolization as the rate‐determining step, this study establishes a clear structure‐activity relationship between ligand geometry and catalytic efficiency. Specifically, the bisphosphine bite angle is found to strongly govern turnover numbers (TONs), with wider bite angles correlating with enhanced CO 2 /ethylene coupling activity. Furthermore, the introduction of moderately bulky substituents on the phosphine ligand is shown to provide an additional boost to catalytic performance. These findings offer rational design principles for the development of next‐generation bisphosphine catalysts for CO 2 valorization.