In nature, nitrogen is commonly fixed as the most reduced form, ammonia (NH3) and as the most oxidized form, i.e. nitrate ion (NO 3-). Nitrogenases catalyze the reduction of N2 into NH3 by using protons and electrons with evolution of H 2. However, the reason why the enzymes waste electrons by evolving H2 has yet to be clarified. We have previously reported (J. Am. Chem. Soc. 2002; 124: 597) pH-dependent heterolytic cleavage of H2 and subsequent reduction of NO3- with evolution of H 2 by iridium complexes in water. We propose herein a catalytic mechanism of nitrogenases, which can account for evolution of H2 in the reduction of N2 to NH3 in relation to a mechanism of the reduction of NO3-.
All Science Journal Classification (ASJC) codes
- Inorganic Chemistry