A Paramagnetic Copper(III) Complex Containing an Octahedral Cu^III S₆ Coordination Polyhedron

Area of Science:

• Inorganic Chemistry
• Coordination Chemistry
• Materials Science

Background:

• Octahedral copper(III) complexes are rare due to their high oxidation state.
• Paramagnetic copper(III) species with spin state S=1 are particularly uncommon.
• Stabilization of unusual metal oxidation states often requires specific ligand environments.

Purpose of the Study:

• To synthesize and characterize a novel octahedral, paramagnetic copper(III) complex.
• To investigate the electronic structure and oxidation state of copper in the synthesized complex.
• To explore the role of bridging thiolato ligands in stabilizing high oxidation states.

Main Methods:

• Heterotrinuclear complex synthesis: [LCo^III Cu^III Co^III L](ClO₄ )₃ ⋅2 Me₂ CO
• Structural characterization of the complex and its reduced form.
• Spectroscopic analysis including X-ray Absorption Spectroscopy (XAS), Extended X-ray Absorption Fine Structure (EXAFS), and Electron Paramagnetic Resonance (EPR) spectroscopy.

Main Results:

• Successful synthesis and characterization of the second known octahedral, paramagnetic copper(III) complex (S=1).
• Six thiolato bridging ligands were found to stabilize the heterotrinuclear species [LCo^III Cu^III Co^III L](ClO₄ )₃ ⋅2 Me₂ CO.
• Spectroscopic data (XAS, EXAFS, EPR) confirmed that the one-electron oxidation to copper(III) is metal-centered, not ligand-centered.

Conclusions:

• The study reports the synthesis of a rare octahedral copper(III) complex stabilized by thiolato ligands.
• The findings provide definitive evidence for metal-centered oxidation in this copper(III) complex.
• This work contributes to the understanding of stabilizing unusual oxidation states in coordination chemistry.