Ammonia formation from dinitrogen complexes

Use of the triphosphine ligand permitted, for the first time, characterization of the metal-containing product (MoBrsietp) in this case) after ammonia formation from a metal-dinitrogen complex. 

This process is an indirect ammonia synthesis. There are three steps including formation of dinitrogen complex, protonation and eduction of ammonia. This method requires complete destruction of complex, otherwise, the N-N bond cannot be disbanded and an effective synthetic cycle for ammonia cannot be realized. The effective way to solve this problem is to supply extra electron by chemistry or electrochemistry in order to realize controllable break of N-N bond and a synthetic recycle from nitrogen to ammonia. ... 

For example, the above presented theoretical results and comparison of those with available experiment clearly indicate that addition of the second (and third) hydrogen molecule to complex [p2n2]Zr( i-Ti2-N2)Zr[p2n2], A1 should be feasible under appropriate laboratory conditions, and formation of ammonia from dinitrogen and dihydrogen molecules could be a catalytic process (see Figure 11). This conclusion should be tested by experimentalists. 

The first indirect evidence for the formation of such complexes is due to Volpin and Shur (1964). They observed that a mixture of an organotitanium compound and a reducing agent absorbs dinitrogen from the gas phase under nonaqueous anaerobic conditions. After the addition of aqueous acid, ammonia was detected. 

Akagi P, Suzuki S, Ishida Y, Hatanaka T, Matsuo T, Kawaguchi H. Reactions of a niobium nitride complex prepared from dinitrogen synthesis of imide and ureate complexes and ammonia formation. Eur J Inorg Chem. 2013 3930—3936. 

Complexes such as [W(PMe2Ph)4(N2)2] react with proton acids, even those as weak as methanol, losing at least one mole of nitrogen, with the formation of ammonia hydrazine. In the best cases, one mole of complex yields two moles of ammonia, all the six electrons for the reduction of the dinitrogen coming from the... 

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