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Coordination-Induced Spin Modulation: Overcoming Spin Blocking in C-H Methylation with High-Spin Ferrous Complexes
Tianyi Zhang1, Matthew V Pecoraro1, Paul J Chirik1
1Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States.
ACS Catalysis
|March 23, 2026
Summary
Researchers controlled iron spin states to activate C-H bonds for methylation reactions. This spin modulation strategy overcomes limitations in earth-abundant metal catalysis, enabling new organometallic chemistry.
Area of Science:
- Organometallic Chemistry
- Catalysis
- Spin State Control
Background:
- Controlling spin states in earth-abundant transition metals is key for catalysis.
- Spin state control is underexplored in organometallic chemistry for reactivity modulation.
Purpose of the Study:
- To develop coordination-induced spin modulation for C-H functionalization.
- To overcome spin blocking in four-coordinate high-spin iron(II) complexes.
Main Methods:
- Utilized monodentate phosphines as spin modulators.
- Employed mechanistic studies, kinetics, stereochemical probes, and computational analysis.
- Characterized a five-coordinate intermediate using NMR spectroscopy.
Main Results:
- Identified PhPMe2 as the optimal spin modulator for C-H methylation of arenes.
- Demonstrated room-temperature C-H methylation via spin state lowering.
- Observed a key five-coordinate intermediate and subsequent σ-agostic complex formation.
Conclusions:
- Coordination-induced spin modulation is an effective strategy for C-H functionalization.
- Overcoming spin blocking enables reactivity in previously unreactive iron complexes.
- This approach advances the use of earth-abundant metals in catalysis.
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