Triphos iridium(III) halide complex photochemistry: triphos arm dissociation

Area of Science:

• Organometallic Chemistry
• Photochemistry
• Inorganic Synthesis

Background:

• Iridium complexes with polydentate phosphine ligands are of interest for their unique reactivity.
• Photolysis can induce structural changes and ligand dissociation in metal complexes.
• Understanding photoinduced transformations is crucial for developing new catalytic and materials applications.

Purpose of the Study:

• To investigate the photochemistry of Ir(triphos)X3 complexes.
• To characterize the photoproducts and their subsequent reactions.
• To elucidate the mechanism of triphos ligand arm dissociation using computational methods.

Main Methods:

• Photolysis of Ir(triphos)X3 complexes in solution and solid state.
• Ligand exchange reactions with pyridine.
• Single-crystal X-ray diffraction for structural characterization.
• Density Functional Theory (DFT) and time-dependent DFT (TDDFT) calculations.

Main Results:

• Photolysis of Ir(triphos)X3 yields insoluble oligomers, which dissolve in pyridine to form mer-Ir(κ(2)-triphos)(py)X3.
• Oxidation of the dangling triphos arm leads to mer-Ir(κ(2)-P,P-triphosO)(py)Cl3, characterized by X-ray diffraction.
• Both mer-isomers photoisomerize to thermally unstable fac-isomers in pyridine.
• DFT/TDDFT calculations suggest a triplet pathway involving ligand arm dissociation and intersystem crossing.

Conclusions:

• The photolysis of Ir(triphos)X3 complexes initiates a cascade of reactions involving ligand dissociation and isomerization.
• The study provides insights into the photochemical behavior of iridium complexes with bulky phosphine ligands.
• Computational modeling is essential for understanding the complex photophysical pathways involved.