Five-coordinate iridium(III) complex with ΔΛ chirality.

Area of Science:

• Organometallic Chemistry
• Coordination Chemistry
• Chiral Catalysis

Background:

• Iridium(III) complexes are crucial in catalysis and materials science.
• Synthesis of bis-chelated iridium(III) complexes often yields chlorine-bridged dimers.
• Understanding the coordination geometry and stability of such complexes is vital.

Purpose of the Study:

• To synthesize and characterize a novel coordinatively unsaturated bis-chelated iridium(III) complex.
• To investigate its structural properties and optical resolution.
• To assess the stability of its enantiomers and their reactivity.

Main Methods:

• Reaction of iridium(III) trichloride with 2-butyl-benzo[h]quinoline (2-BubzqH) in a 1:2 molar ratio.
• Single-crystal X-ray diffraction for structural analysis.
• Chiral chromatography for optical resolution and vibrational circular dichroism for enantiomer stability confirmation.

Main Results:

• A five-coordinate, distorted square pyramidal iridium(III) complex, [Ir(2-Bubzq)2Cl], was successfully synthesized, contrary to expected dimer formation.
• Optical resolution yielded stable Δ and Λ enantiomers.
• The complex reacted rapidly with carbon monoxide and 1,10-phenanthroline, preserving its absolute configuration.

Conclusions:

• The synthesis of [Ir(2-Bubzq)2Cl] provides a new route to coordinatively unsaturated iridium(III) complexes.
• The resolved enantiomers exhibit remarkable stability and maintain chirality during reactions.
• This study offers insights into the synthesis, structure, and stereochemical behavior of iridium(III) complexes.