Conversion of N₂ into oxadiazoles promoted by a multinuclear samarium complex

Area of Science:

• Inorganic Chemistry
• Organometallic Chemistry
• Materials Science

Background:

• Nitrogenous compounds are vital for life, but their synthesis often relies on ammonia.
• Transforming nitrogen gas (N₂) into high-value organic compounds without using ammonia is a significant challenge.
• The chemistry of rare-earth metal dinitrogen complexes is less explored compared to d-block metals.

Purpose of the Study:

• To investigate the single-electron reduction of a tetrametallic samarium dinitrogen complex.
• To explore the derivatization chemistry of rare-earth metal dinitrogen complexes.
• To synthesize novel nitrogen-containing organic compounds directly from N₂ using rare-earth metal complexes.

Main Methods:

• Single-electron reduction of a tetrametallic samarium dinitrogen complex [L₄Sm₄N₂(THF)₂] in THF.
• Isolation and characterization of ionic complexes [L₄Sm₄N₂]M(THF)₆ (M = K, Na).
• Reaction of the samarium dinitrogen complex with aroyl chlorides to form oxadiazole compounds.

Main Results:

• Successfully synthesized ionic complexes 2 and 3 via single-electron reduction.
• Obtained complex 4 with side-on coordination of Na to the dinitrogen molecule.
• Achieved a more nucleophilic complex 5 [L₄Sm₃N₂Na₃] upon extended reaction.
• Synthesized oxadiazole organic compounds from N₂ using the rare-earth metal complex.

Conclusions:

• Rare-earth metal dinitrogen complexes can be derivatized through single-electron reduction.
• The [(N₂)^4-] unit facilitated the direct conversion of N₂ into valuable organic compounds.
• This study opens new avenues for nitrogen fixation and the synthesis of nitrogen-containing organic molecules.