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Substituent-Induced Control of fac/mer Isomerism in Azine-NHC Fe(II) Complexes
Ulises Carrillo1, Antonio Francés-Monerris2, Anil Reddy Marri3
1Université de Lorraine, CNRS, L2CM, F-57000 Metz, France.
ACS Organic & Inorganic Au
|March 1, 2023
Summary
This study details the stereoselective synthesis of iron(II) complexes with azine-NHC ligands. Ligand steric bulk controls facial versus meridional selectivity, impacting complex properties.
Area of Science:
- Organometallic Chemistry
- Coordination Chemistry
- Stereoselective Synthesis
Background:
- Iron(II) complexes are crucial in catalysis and materials science.
- Controlling the geometry (facial vs. meridional) of ligands around metal centers is key to tuning complex properties.
- Azine-N-heterocyclic carbene (NHC) ligands offer tunable steric and electronic properties for coordination chemistry.
Purpose of the Study:
- To achieve stereoselective synthesis of geometrical iron(II) complexes using azine-NHC ligands.
- To investigate the influence of ligand steric demand on facial (fac) and meridional (mer) selectivity.
- To explore the impact of the fac/mer configuration on the structural, optical, and electrochemical properties of the synthesized complexes.
Main Methods:
- Synthesis of novel iron(II) complexes incorporating azine-NHC ligands.
- Systematic variation of the steric bulk of the azine unit, particularly at the α-position and on the pyridyl coordinating units.
- Structural characterization (e.g., X-ray crystallography) and analysis of optical and electrochemical properties.
Main Results:
- Stereoselective synthesis of facial and meridional iron(II) complexes was achieved.
- Meridional selectivity was favored with bulky 5-mesityl-substituted pyridyl coordinating units.
- Increased steric hindrance at the α-position unexpectedly led to exclusive facial configuration, contrasting with other bidentate ligands.
Conclusions:
- The steric properties of the azine unit in azine-NHC ligands are the primary determinant of fac/mer selectivity in iron(II) complexes.
- The carbene nature has a minimal effect on the observed stereoselectivity.
- The fac/mer ligand configuration significantly influences the structural, optical, and electrochemical characteristics of the iron(II) complexes.
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