Effect of the [Fe(salen)]2-μ-oxo Catalyst Electronic Structure on Reductive Hydroamination
Emily Pocock1, Nathan J Buxton2, Martin Diefenbach3
1Department of Chemistry, University of Bath, Claverton Down, Bath BA2 7AY, U.K.
Inorganic Chemistry
|December 20, 2025
Summary
Iron-salen complexes catalyze nitroarene reductive hydroamination. Ligand electronics tune efficiency, with para-CF3 substituted iron-salen complexes showing superior performance in hydrogen atom transfer catalysis.
Area of Science:
- Organometallic Chemistry
- Catalysis
- Organic Synthesis
Background:
- Salen ligands are versatile in transition metal catalysis, offering tunable electronics and redox stability.
- Iron-salen complexes are increasingly explored for catalytic applications due to iron's abundance and low toxicity.
Purpose of the Study:
- To synthesize and compare three electronically differentiated [Fe(salen)]2(μ-oxo) complexes.
- To investigate their efficacy in catalytic reductive hydroamination (HA) of nitroarenes with alkenes.
- To elucidate the mechanism, focusing on the role of ligand electronics in hydrogen atom transfer (HAT).
Main Methods:
- Synthesis of electronically varied iron-salen complexes.
- Catalytic testing in reductive hydroamination reactions.
- Mechanistic studies including UV-vis spectroscopy, cyclic voltammetry, DFT calculations, and substrate LUMO energy analysis.
Main Results:
- Successful synthesis of three [Fe(salen)]2(μ-oxo) complexes with distinct electronic properties.
- Demonstration of catalytic activity in nitroarene HA.
- Identification of iron-hydride intermediates and a hydrogen atom transfer (HAT) mechanism.
- The complex with para-CF3 substituents exhibited enhanced catalytic efficiency and broader substrate scope.
Conclusions:
- Ligand electronics critically influence the performance of iron-salen catalysts in HAT-based reactions.
- The para-CF3 substituted complex represents a highly effective precatalyst for reductive hydroamination.
- This work provides a framework for designing advanced iron-salen catalysts by tuning ligand electronics.
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