A Dinuclear Iridium(V,V) Oxo-Bridged Complex Characterized Using a Bulk Electrolysis Technique for Crystallizing...

Area of Science:

• Inorganic Chemistry
• Electrochemistry
• Materials Science

Background:

• Highly oxidized metal complexes are challenging to synthesize and handle using conventional methods.
• Existing electrochemical and crystallization techniques often employ oxidation-prone reagents, limiting access to high oxidation states.

Purpose of the Study:

• To develop a general method for preparing and crystallizing highly oxidized metal complexes.
• To overcome limitations of conventional methods by using oxidation-resistant compounds.

Main Methods:

• Substitution of oxidation-prone electrolytes and precipitants with oxidation-resistant alternatives (CsPF6 in acetonitrile, CCl4).
• Bulk electrolysis at high potentials (1.9 V vs NHE) for synthesis.
• Crystallization and characterization of metal complexes.
• Density Functional Theory (DFT) and Time-Dependent DFT (TD-DFT) calculations.

Main Results:

• A novel Iridium(V,V) mono-μ-oxo dimer was synthesized and characterized, representing the highest isolated oxidation state in the system.
• The synthesis of the Ir(V,V) complex was only achievable electrochemically, not chemically.
• DFT calculations revealed oxidation centered on the Ir-O-Ir core, facilitated by the pyalk ligand.
• TD-DFT simulations explained the royal blue color due to mixed LMCT and d-d electronic excitations.
• A related monomeric Ir(V) complex was also synthesized, demonstrating the method's general applicability.

Conclusions:

• The developed method provides a general approach for preparing and crystallizing highly oxidized metal complexes.
• Oxidation-resistant compounds (CsPF6, CCl4) are effective alternatives for electrochemical studies and crystallization.
• The synthesis of unprecedented high oxidation state complexes like the Ir(V,V) dimer is now feasible.