Could a very strong reducing agent like lithium aluminium hydride or a very strong oxidizing agent like manganese heptoxide react with $\ce{N2}$? Usually when people talk about reactive substances they emphasize either strong electron acceptors or donors. I am wondering if using such compounds could be employed in a brute force method of dissociating $\ce{N2}$ molecules. I know there exist industrial methods for that already, but i'm poking around to see if maybe there's a way to do it under atmospheric pressure without tailored molecules like enzymes or organometallic complexes.

  • 2
    $\begingroup$ "since nitrogen can both give and take electrons to achieve a more stable configuration" Huh? $\endgroup$
    – Zhe
    Aug 13 '20 at 0:59
  • $\begingroup$ What's the point of this question exactly? Agents you mention don't react with molecular nitrogen in standard STP. Still bacteria can reduce it enzymatically and ammonia is produced industrially in via reduction with H2. And I agree with Zhe that your last sentence there isn't OK at all. $\endgroup$
    – Mithoron
    Aug 13 '20 at 1:02
  • $\begingroup$ ok, ill remove that part,i wanted to know if a brute force method could work in destroying the N2 molecule $\endgroup$
    – Francis L.
    Aug 13 '20 at 1:06
  • $\begingroup$ It is hard to make a full answer to questions where the answer is simply: "no". There is a reason why it is a billion-dollar problem, and you may not find the answer to this problem on SE. $\endgroup$
    – Greg
    Aug 13 '20 at 1:37
  • $\begingroup$ You mean like this? $\endgroup$ Aug 13 '20 at 15:43

I know there exist industrial methods for that already, but im poking around to see if maybe there's a way to do it under atmospheric pressure without tailored molecules like enzymes or metalorgnic complexes

Though Haber process which was used to industrially produce ammonia was well-known, some researchers have also attempted to split nitrogen molecules using metal complexes:

  1. Chirik et.al (Nature, volume 427, pages 527–530(2004)) attempted to split nitrogen molecules by using a zirconium complex containing two bulky chemical groups called methylated cyclopentadienyl. The complex was the right size to snuggle up to both nitrogen atoms and give an electron to each atom. This double donation take place in an organic solvent at 100 °C and atmospheric pressure, disrupts the triple bond. Further reactions in the same solution then finish the job of splitting the nitrogen molecules and adding hydrogen atoms to make ammonia. (source)
  2. Carbon monoxide and a molecule containing hafnium to break apart nitrogen and create a fertilizer called oxamide. (source)
  3. John Mark P. Martirez and Emily A. Carter at Princeton University propose a gold-molybdenum catalyst that could split the nitrogen triple bond at room temperature using energy from visible light. That dissociation step is the primary limit on the reaction rate in the Haber-Bosch process. (source)

Brute force would be really good if it were also clever. An article on using a large spark generator (Ref 1) discussed controlled experiments and used to data to estimate the amount of nitrogen oxides produced by lightning. I suppose cleverness could be added if a proper surface (i.e., catalyst) could be found, or if a proper reaction could be designed.

The trouble is, brute force is pretty random, and destroys as much of the product (even more!) than it converts of the starting material (N2). Oxidation is usually considered for brute force work. However, the Haber process uses heat and an iron + KOH catalyst at 400-450 degrees C to make ammonia. The heat is to make it fast enough, and the catalyst needs the high temperature to become active.

The equilibrium is favored to produce more NH3 at lower temperatures: $$N2 + 3H2 --> 2NH3$$ is exothermic. (Ref 2)

Now I speculate: the Haber approach relies on the dissociative adsorption of N2 upon the metal (iron is cheapest, but there are others that work well too). The actual mechanism appears to be multi-step, with dissociation of nitrogen, and hydrogen, and stepwise addition of H to N to form NH3. Suppose you took a mixture of N2 and H2 and dissociated the hydrogen with a spark; I wonder if the H atoms would combine with N2 and start the process of dissociating the N2 molecule before recombining to H2.

So, a spark at low temperature (and perhaps at moderate pressure) might initiate a reaction in N2 + H2 like a spark in a mixture of H2 + O2. Oh no, it couldn't be that easy!

Ref 1: https://agupubs.onlinelibrary.wiley.com/doi/pdfdirect/10.1029/1999JD901138

Ref 2: https://en.wikipedia.org/wiki/Haber_process


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