INOR 593 |
| Despite a lot of effort, little is known about how dinitrogen is reduced to ammonia in MoFe nitrogenases (left Figure). Dinitrogen is reduced by protons and electrons in a reaction that is on first sight not that selective. At optimal conditions at least one molecule of dihydrogen is produced (yield ammonia £ 75%). Under a deuterium atmosphere, HD is produced. The rate of HD formation is proportional to the dinitrogen pressure and only takes place when dinitrogen is reduced. Whether dinitrogen reduction takes place at the Mo site or on Fe is still a matter of debate. Recently, our group published a catalytic system (right Figure), which is capable of reducing dinitrogen to ammonia [1]. Reduction of dinitrogen takes place end-on at molybdenum and proceeds via 13 intermediates of which many were isolated and fully characterized. The rate limiting step of dinitrogen reduction is the replacement of ammonia by dinitrogen. As a result the yield in ammonia increases from 65% at 1 atm. to 71% at 2 atm. In the present study we reduce dinitrogen at higher pressures in order to find the maximum yield in ammonia for this artificial system. In addition we want to see whether HD formation takes place proportional to the dinitrogen pressure. In the end, we want to relate our findings to those of the Natural system in order to shed some light on how dinitrogen is reduced by Nature. [1] (a) Yandulov, D. V.; Schrock, R. R., Science 2003, 301, 76. (b) Yandulov, D. V.; Schrock, R. R., J. Am. Chem. Soc. 2002, 124, 6252. (c) Yandulov D. V.; Schrock, R. R., Inorg. Chem. 2005, 44, 1103.
|
|
Inorganic Catalysts
7:00 PM-10:00 PM, Tuesday, August 21, 2007 BCEC -- Exhibit Hall - B2, Poster
Sci-Mix
Division of Inorganic Chemistry |
