ABSTRACT The rational design of earth‐abundant transition metal catalysts has gained significant attention as an effective approach to modulate the efficiency in catalytic reactions. This study presents a comprehensive investigation of electronic modulations within the salen ligand framework and their influence on the catalytic behavior of iron(III)‐complexes in hydroboration of ketones. A series of structurally well‐defined Fe(III)salen complexes ( Fe‐TB , Fe‐TF , and Fe‐TDF ) bearing electronically diverse substituents were synthesized and characterized. Systematic evaluation of their catalytic activity revealed that subtle variations in the electronic nature of the phenoxy and diimine moieties markedly impact the activation of the borane and the subsequent reduction of ketones. Among the catalysts examined, the di‐fluoro/trifluoromethyl‐substituted complex Fe‐TDF exhibited the highest activity, achieving excellent yields and functional‐group tolerance for a wide range of aromatic, aliphatic, and heterocyclic ketones under a low catalyst loading. Comparative analysis of the catalytic series established a structure‐reactivity correlation, demonstrating that electron‐withdrawing substituents enhance the electrophilicity of the iron center, thereby facilitating substrate bond activation and accelerating the reaction. This study highlights how targeted electronic tuning of the salen framework provides a powerful strategy for developing efficient, base‐metal catalysts for sustainable catalytic reactions.
L et al. (Mon,) studied this question.