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Atropisomerism in a thermally switchable, cyclometallated iridium complex
Ashlee J Howarth1, David L Davies, Francesco Lelj
1Department of Chemistry, University of British Columbia, Vancouver, BC, Canada.
Dalton Transactions (Cambridge, England : 2003)
|July 18, 2012
Summary
Researchers isolated two stable diastereomeric atropisomers of a cyclometallated iridium complex. This discovery marks the first metal-containing atropisomers with a rotational axis not between chelating atoms, convertible via pyrene motion.
Area of Science:
- Organometallic Chemistry
- Stereochemistry
- Photophysical Studies
Background:
- Atropisomerism is typically observed in molecules with restricted rotation around single bonds.
- Cyclometallated iridium complexes are known for their unique photophysical and electrochemical properties.
- Pyrene-containing ligands can impart interesting electronic and structural characteristics.
Purpose of the Study:
- To isolate and characterize novel atropisomers of cyclometallated iridium complexes.
- To investigate the structural and dynamic properties of metal-containing atropisomers.
- To explore the influence of a pyrene moiety on atropisomer stability and interconversion.
Main Methods:
- Synthesis of a pyrene functionalized pyridine imine ligand.
- Formation and isolation of a cyclometallated iridium complex.
- Characterization of diastereomeric atropisomers using techniques like NMR spectroscopy and X-ray crystallography.
- Thermal conversion studies to analyze the rocking motion of the pyrene moiety.
Main Results:
- Successfully isolated two stable diastereomeric atropisomers of the cyclometallated iridium complex.
- These represent the first reported metal-containing atropisomers where the axis of rotation is not between two chelating atoms.
- Demonstrated thermal interconversion of atropisomers through a rocking motion of the pyrene group.
Conclusions:
- The study presents a new class of metal-containing atropisomers with unique rotational axes.
- The pyrene moiety plays a crucial role in the observed atropisomerism and dynamic behavior.
- These findings open new avenues for designing functional organometallic materials with controlled stereochemistry.
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