Effect of the [Fe(salen)] ₂ -μ-oxo Catalyst Electronic Structure on Reductive Hydroamination

Salen ligands are privileged scaffolds in transition metal catalysis due to their electronic tunability and capacity to stabilize diverse oxidation states. Herein, we report the synthesis and comparative study of three electronically differentiated [Fe(salen)]₂(μ-oxo) complexes and their application in catalytic reductive hydroamination (HA) of nitroarenes with alkenes. A mechanistic framework involving iron-hydride intermediates and hydrogen atom transfer (HAT) was developed, revealing that modulation of the salen ligand electronics significantly impacts product distribution and catalytic efficiency. Systematic investigation of substrate LUMO energies and precatalyst UV-vis spectroscopy, cyclic voltammetry, along with DFT calculations on the key HAT step, was undertaken. Notably, the complex bearing <i>para</i>-CF₃ substituents outperformed its analogues across a range of olefin partners. These findings underscore the critical role of ligand electronics in tuning HAT-based catalysis.