Catalytic Dinitrogen Reduction

The catalytic reduction of dinitrogen to ammonia in biological systems is thermodynamically favorable overall and takes place according to equation 6.2 ... 

A series of model studies initiated in the early 1960s by the groups of Chatt and Hidai demonstrated that dinitrogen could be bound and reduced to ammonia at a single metal centre by Mo and W complexes (Chatt et al., 1978 Hidai, 1999). However, although examples of virtually all the proposed intermediates in a Chatt cycle were isolated, no catalytic reduction of N2 to NH3 was ever achieved. Catalytic reduction of dinitrogen to ammonia... 

Structural basis of biological nitrogen fixation, Phil. Trans. R. Soc., 363, 971-984. Schrock, R.R. (2005) Catalytic reduction of dinitrogen to ammonia at a single molybdenum center,... 

Scheme 18. Proposed mechanism for catalytic reduction of dinitrogen by Mo(red). ...

Scheme 1. Proposed mechanism for the catalytic reduction of dinitrogen at a molybdenum site in nitrogenase...

Studies on model polynuclear catalytic systems have confirmed that for the catalytic reduction of dinitrogen under mild conditions, it is necessary to use a polynuclear transition metal complex capable of donating four electrons to form the hydrazine derivative. 

In this article, the reasons for this mechanism in catalytic reduction of N2 will be considered, and results for electron transfer in biological N2 reduction and model synthetic systems will be compared. Hopefully, this consideration will lead to understanding how inert dinitrogen can be turned into a very active substrate readily reacting in solution in the presence of comparatively mild reducing agents. 

In conclusion, it can be said that enzymatic reduction of dinitrogen requires substrate coordination on the polynuclear FeMo cofactor. To ensure catalytic reduction of the substrate the reduced cofactor is situated at a distance typical of... 

Dmitry V. Yandulov and Richard R. Schrock Catalytic reduction of dinitrogen to ammonia at a single Mo center... 

HlPTNsN] species can be prepared for Cr [68]. Attempted catalytic reduction of dinitrogen under standard conditions with [HlPTN3N]Cr=N yields only 0.8 equiv... 

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