A Dinitrogen Dicopper(I) Complex via a Mixed-Valence Dicopper Hydride

Area of Science:

• Inorganic Chemistry
• Organometallic Chemistry
• Catalysis

Background:

• Copper complexes are vital in various catalytic processes.
• Dinitrogen (N2) activation remains a significant challenge in chemistry.
• Tris(pyrazolyl)borate (Tp) ligands offer versatile coordination environments for metal centers.

Purpose of the Study:

• To synthesize and characterize a novel dinuclear copper-dinitrogen complex.
• To investigate the electronic structure and reactivity of the N2 ligand.
• To explore the catalytic potential of the copper complex in small molecule activation.

Main Methods:

• Low-temperature synthesis and isolation of copper complexes.
• X-ray crystallography for structural determination.
• Density Functional Theory (DFT) studies for electronic structure analysis.
• Reactivity studies involving addition of various ligands and substrates.

Main Results:

• A bridging dinitrogen complex, [(iPr2)TpCu]2(μ-1,2-N2), was successfully synthesized.
• X-ray crystallography confirmed a slightly activated N2 ligand (N-N bond length: 1.111(6) Å).
• DFT studies revealed cooperativity in the dinuclear Cu-N2-Cu interaction.
• The complex readily releases N2 upon addition of MeCN, CNAr(2,6-Me)2, or O2.
• A key intermediate, [(iPr2)TpCu]2(μ-H), was isolated and showed reduction of unsaturated substrates like CO and phenylacetylene.

Conclusions:

• The synthesized dinuclear copper complex effectively coordinates and activates dinitrogen.
• The complex demonstrates cooperative effects between the two copper centers.
• The intermediate hydride complex shows potential for catalytic reduction of unsaturated molecules.