Abiological nitrogen fixation using homogeneous catalysts

Abiological nitrogen fixation describes chemical processes that fix (react with) N2, usually with the goal of generating ammonia.

The dominant technology for abiological nitrogen fixation is the Haber process, which uses iron-based heterogeneous catalysts and H2 to convert N2 to NH3.

[1] An early influential discovery of abiological nitrogen fixation was made by Vol'pin and co-workers in Russia in 1970.

Most catalytic systems operate according to the following stoichiometry: The reductive protonation of metal dinitrogen complexes was popularized by Chatt and coworkers, using Mo(N2)2(dppe)2 as substrate.

A Mo-PCP (PCP = phosphine-NHC-phosphine) complex exhibits >1000 turnovers when the reducing agent is samarium(II) iodide and the proton source is methanol.

[12] Processes that involve oxidising the lithium metal are however of little practical interest, since they are non-catalytic and re-reducing the Li+ ion residue is difficult.

Hypothesized cycle for M-catalysed nitrogen fixation according to Chatt et al.
An early well-defined catalyst for nitrogen reduction. [ 2 ]
structure of Nishibayashi's Mo 2 (N 2 ) 3 complexes.
An Fe(0)-N 2 catalyst. [ 1 ]
Dinitrogen activation by a borylene .