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Electronic structure and reactivity of three-coordinate iron complexes
1Department of Chemistry, University of Rochester, Rochester, New York 14627, USA. holland@chem.rochester.edu
Accounts of Chemical Research
|July 24, 2008
Summary
Coordination number significantly impacts iron complex reactivity, distinct from oxidation state. Three-coordinate iron complexes exhibit unique electronic structures and catalytic potential for oxidation and reduction reactions.
Area of Science:
- Coordination Chemistry
- Organometallic Chemistry
- Catalysis
Background:
- Traditionally, metal identity and oxidation state dominate coordination compound reactivity discussions.
- Coordination number, however, is an equally critical factor influencing a metal's chemical behavior.
- Octahedral (six-coordinate) iron complexes are well-studied, but lower coordination numbers present unique properties.
Purpose of the Study:
- To explore the distinct properties and reactivity of three-coordinate iron complexes.
- To synthesize and characterize iron complexes with coordination number three across various oxidation states.
- To elucidate the electronic structures and bonding principles governing these low-coordinate iron systems.
Main Methods:
- Synthesis of three-coordinate iron complexes using bulky, anionic, bidentate beta-diketiminate ligands.
- Systematic studies of electronic structures to interpret observed properties.
- Investigation of reactivity patterns, including ligand interactions and catalytic applications.
Main Results:
- Successfully synthesized three-coordinate iron complexes in +1, +2, and +3 oxidation states with trigonal-planar geometry.
- Demonstrated that these complexes are generally high spin, featuring singly occupied orbitals for pi interactions.
- Revealed unique reactivity, such as iron(II) hydride complexes undergoing addition and radical reactions, and iron(III) imido complexes facilitating hydrogen atom abstraction.
Conclusions:
- Coordination number is as crucial as oxidation state in determining iron complex reactivity.
- Three-coordinate iron complexes exhibit unusual bonding and reactivity, distinct from their six-coordinate counterparts.
- These findings suggest potential for novel catalysts in oxidation/reduction and relevance to biological systems like nitrogenase.
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