Reduction of Dinitrogen to Ammonia Catalyzed by Molybdenum Diamido Complexes

Abstract

[Ar₂N₃]Mo(N)(O-t-Bu), which contains the conformationally rigid pyridine-based diamido ligand, [2,6-(ArNCH₂)₂NC₅H₃]^2- (Ar = 2,6-diisopropylphenyl), can be prepared from H₂[Ar₂N₃], butyllithium, and (t-BuO)₃Mo(N). [Ar₂N₃]Mo(N)(O-t-Bu) serves as a catalyst or precursor for the catalytic reduction of molecular nitrogen to ammonia in diethyl ether between -78 and 22 °C in a batchwise manner with CoCp*₂ as the electron source and Ph₂NH₂OTf as the proton source. Up to ∼10 equiv of ammonia can be formed per Mo with a maximum efficiency in electrons of ∼43%.