In nature, several plants possess the capacity to absorb atmospheric N2, which is subsequently transformed by symbiotic microorganisms into ammonia. The mechanism of action of the corresponding enzymes, nitrogenases, involves transition metal clusters. Industrially, synthesis of ammonia through the Haber Bosch process relies on a catalytic hydrogenation of dinitrogen using heterogeneous catalysts. This process is highly energetically demanding as it requires very high pressures and temperatures.
It is rather a challenge to achieve the catalytic reduction of N2 into amines (NR3 = NH3 or N(SiMe3)3), as a total of six electrons and six “R+” have to be added to N2 in stepwise and/or concerted manner, imposing drastic constraints on the metal fragment chosen for that purpose.
We have been focusing on the development of unsaturated metal fragments (of Mo and Fe) capable of coordinating N2 in order to study its stepwise functionalization as well as to probe their competence as catalysts in these processes. The results of our endeavors will be presented.