Intermolecular C-H Bond Activation by a Cationic Iridium(III) Dichloride Phenanthroline Complex

Area of Science:

• Organometallic Chemistry
• Catalysis
• Chemical Kinetics

Background:

• C-H activation is a crucial transformation in synthetic chemistry.
• Iridium complexes are known catalysts for C-H activation.
• Understanding gas-phase reactivity provides fundamental insights into catalytic mechanisms.

Purpose of the Study:

• To investigate the C-H activation and H/D exchange capabilities of a cationic iridium(III) dichloride phenanthroline complex.
• To compare the selectivity of this system in the gas phase versus condensed phase.
• To elucidate the reaction mechanism using kinetic and computational methods.

Main Methods:

• Gas-phase kinetic studies of C-H activation and H/D exchange reactions.
• Determination of rate constants and kinetic isotope effects for various substrates.
• Density Functional Theory (DFT) calculations at the M06/QZVP level.

Main Results:

• The iridium complex effectively cleaves benzylic and unactivated secondary C-H bonds.
• Unique selectivity was observed compared to condensed-phase systems.
• Gas-phase rate constants and kinetic isotope effects were quantified.
• DFT calculations supported the experimental findings and provided mechanistic insights.

Conclusions:

• The cationic iridium complex is a potent catalyst for gas-phase C-H activation and H/D exchange.
• The observed selectivity offers new possibilities for targeted functionalization.
• Gas-phase studies are valuable for understanding fundamental catalytic processes.