Nitrogen adsorption and hydrogenation on a MoFe6S9 complex

Abstract

The enzyme nitrogenase catalyzes the biological nitrogen fixation where 2 is reduced to NH3. Density functional calculations are presented of the bonding and hydrogenation of 2 on a MoFe6S9 complex constructed to model aspects of the active site of nitrogenase. 2 is found to bind end on to one of the Fe atoms. A complete energy diagram for the addition of hydrogen to the MoFe6S9 complex with and without 2 is given, and a mechanism for ammonia synthesis is proposed on this basis. © 1999 The American Physical Society.