A Terminal Iridium Oxo Complex with a Triplet Ground State

Area of Science:

• Inorganic Chemistry
• Organometallic Chemistry
• Catalysis

Background:

• Iridium complexes are crucial in catalysis, but their oxo derivatives with open-shell ground states are less understood.
• Hydrogen atom transfer (HAT) is a key reaction mechanism in many chemical transformations.

Purpose of the Study:

• To synthesize and characterize a terminal iridium oxo complex with an open-shell ground state.
• To investigate the electronic structure and reactivity of the novel iridium oxo species.
• To determine the energetics and contributing factors of the hydrogen atom transfer (HAT) process.

Main Methods:

• Isolation of the iridium oxo complex via hydrogen atom transfer (HAT) from an iridium(II) hydroxide precursor.
• Electronic structure calculations to analyze spin delocalization.
• Oxo transfer reactions to probe reactivity.
• Calorimetric and computational methods to determine bond dissociation free energy (BDFE) for the IrO-H bond.

Main Results:

• Successfully isolated a terminal iridium oxo complex exhibiting an open-shell (S=1) ground state.
• Electronic structure analysis confirmed significant spin delocalization onto the oxygen atom.
• The iridium oxo moiety demonstrated ambiphilic reactivity in oxo transfer reactions.
• The IrO-H bond dissociation free energy was found to be sufficient for abstraction of hydrogen atoms from C-H bonds.

Conclusions:

• The study presents a novel open-shell iridium oxo complex with significant spin delocalization.
• The complex displays ambiphilic reactivity, highlighting its potential as a catalytic intermediate.
• The quantified HAT thermochemistry provides insights into the feasibility of C-H bond functionalization.