4 Apr 2008

Nitrogenase primary literature

Literature Discussion

Submitted by Adam R. Johnson, Harvey Mudd College
Categories
Description: 
Some in-class materials for discussion of the nitrogenase enzyme, including some background reading on the bacterial process, the industrial process, X-ray structure data of the P-cluster and the Mo-Fe cluster, and Schrock's reaction cycle that models the biological process.  Also included are the literature sources I use in my in-class discussion of nitrogenase;  2 X-ray crystal structures by Rees, and the synthetic work by Schrock.
AttachmentSize
Microsoft Office document icon student handout97 KB
Implementation Notes: 
I start with the industrial process (Haber-Bosch) of nitrogen fixation, discussing the work that went into discovery of the process, the thermodynamics involved, the chemical engineering involved. Then I change gears and discuss the biological process, 1 atm, 25 °C, emphasizing that we as chemists have a long way to go to solve the problems nature has chosen to solve. I provide links to the original literature and discuss the main features of the crystallographic data in class.
Time Required: 
1-2 class periods, depending on depth
Creative Commons License: 
Creative Commons Licence

Comments

It is important for teachers to be aware that a lot of this is very controversial. For example, most people in the field don't believe in N2 going into the center of the cofactor (because there is an atom there, discovered in 2002), and Schrock's model doesn't explain how non-molybdenum nitrogenases work. One of the best recent references is Kästner, J.; Blöchl, P. E., "Ammonia Production at the FeMo Cofactor of Nitrogenase: Results from Density Functional Theory," J. Am. Chem. Soc. 2007, 129, 2998-3006. I also wrote a review in Comprehensive Coordination Chemistry 2, vol. 8, which sums up some of the current models.

I used this group of papers for one literature discussion topic in my upper level inorganic course this fall.  It worked quite well.  I pulled together another set of papers on water oxidation as a second discussion topic, using these papers and the overview they provide as something of a guide.  I will try to get those posted here sometime.

I end the semester of upper-level inorganic chemistry with a two-week period of reading and presenting contributions of chemists to address issues of importance to society, including nitrogen fixation. Over the last couple of years, the students have collected the following articles that provide updates / perspectives on this topic:

Ertl, G. "Reactions at Surfaces: From Atoms to Complexity (Nobel Lecture)", Angew. Chem. Int. Ed. 2008, 47, 3524 – 3535

Hoffman, B. et al "Nitrogenase: A Draft Mechanism", Accounts of Chemical Research 2013, 46, 587–595.

Jia H-P et al "Mechanistic aspects of dintirgen cleavage and hydrogenation to produce ammonia in catalysis and organometallic chemistry: relevance of hydride bonds and dihydrogen", Chem. Soc. Rev. 2014, 43, 547.

Spatzal, T.,  et al "Evidence for interstitial carbon in nitrogenase FeMo cofactor", Science 2011, 334, 940-940.

Anderson, J.S. et al "Catalytic conversion of nitrogen to ammonia by an iron model complex", Nature 2013, 501, 84–87. doi:10.1038/nature12435

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