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Updated: Jun 21, 2025
09:37
Imine Metathesis by Silica-Supported Catalysts Using the Methodology of Surface Organometallic Chemistry
Published on: October 18, 2019
9.6K
Square-planar imido complexes of cobalt: synthesis, reactivity and computational study
Jackson A Reyna1, V Mahesh Krishnan1, Roberto Silva Villatoro1
1Department of Chemistry, University of Texas at San Antonio (UTSA), San Antonio, TX 78249, USA. zachary.tonzetich@utsa.edu.
Dalton Transactions (Cambridge, England : 2003)
|July 9, 2024
Summary
New cobalt imido complexes were synthesized and characterized. These complexes exhibit hydrogen atom transfer reactivity but lack catalytic activity for amination or aziridination, suggesting complex electronic structures.
Area of Science:
- Organometallic Chemistry
- Coordination Chemistry
- Catalysis Research
Background:
- Cobalt complexes with phosphine-based ligands are of interest for catalytic applications.
- Imido ligands offer unique electronic properties and reactivity pathways in transition metal chemistry.
Purpose of the Study:
- To synthesize and characterize novel four-coordinate cobalt imido complexes.
- To investigate the reactivity of these imido complexes, including hydrogen atom transfer and potential catalytic applications.
- To explore the electronic structure of the imido and related tetrazido complexes.
Main Methods:
- Synthesis of cobalt imido complexes using aryl azides and a PNP ligand.
- X-ray crystallography for structural determination.
- Reactivity studies with hydrogen atom donors (TEMPOH).
- Density Functional Theory (DFT) calculations for electronic structure analysis.
Main Results:
- Successfully synthesized four-coordinate cobalt imido complexes [Co(NAr)(PNP)].
- Observed unusual square-planar geometry and nearly linear imido units.
- Demonstrated hydrogen atom transfer from TEMPOH to the imido nitrogen, forming amido complexes.
- Found no catalytic activity for C-H amination or aziridination with tested substrates.
- Synthesized a tetrazido complex [Co(N4Ph2)(PNP)] with excess azide.
- DFT calculations suggest a low-spin cobalt(II) ion coupled to an iminyl radical.
Conclusions:
- The synthesized cobalt imido complexes display interesting structural and electronic properties.
- While capable of H atom transfer, they do not catalyze C-H amination or aziridination.
- The electronic structure involves a cobalt(II) radical character, influencing their reactivity.
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