Catalytic NH₃ oxidation to N₂ by hydrogen atom abstraction using a low-valent molybdenum complex

Area of Science:

• Organometallic Chemistry
• Catalysis
• Nitrogen Chemistry

Background:

• Ammonia oxidation is a key transformation in nitrogen chemistry.
• Developing efficient catalysts for selective ammonia oxidation is crucial.
• Phenoxyl radicals can act as hydrogen atom acceptors.

Purpose of the Study:

• To investigate the catalytic activity of novel molybdenum complexes.
• To explore the use of phenoxyl radicals in ammonia oxidation.
• To determine the efficiency of these catalysts in producing nitrogen gas.

Main Methods:

• Synthesis of fac-[(CO)3Mo(P^tBu2N^Ph2)(L)] complexes where L = acetonitrile or ammonia.
• Catalytic oxidation of ammonia using phenoxyl radicals as hydrogen atom acceptors.
• Quantification of nitrogen gas produced per molybdenum center.

Main Results:

• The molybdenum complexes successfully catalyzed ammonia oxidation to nitrogen gas.
• The use of sterically bulky trityl-substituted phenoxyl radicals significantly enhanced nitrogen yield.
• Up to 88 equivalents of N2 were generated per Mo center with the bulky radical.

Conclusions:

• The studied molybdenum complexes are effective catalysts for ammonia oxidation.
• Steric bulk of the phenoxyl radical is a critical factor for high catalytic efficiency.
• This system offers a promising route for nitrogen gas generation from ammonia.