Abstract: Complexes of the transition met al-containing model compounds with dinitrogen (N₂)M(NH₂)₃(NH₃) and (N₂)M(SH)₃(NH₃)(-OCH₂COO^-) [MMo,V, Fe] were studied by the density functional theory. The relative energetics of the reduction of N₂ to ammonia by the proton-electron transfer to the dinitrogen derivative was predicted. The calculated results show that there is a strong interaction between the Mo center and dinitrogen and the V…NN interaction is relatively weak, whereas the Fe center cannot bind N₂. The homocitrate ring opening in the simplified Mo-containing fragment in the FeMoco was predicted to be manipulable by controlling the spin multiplicity and oxidation state of the transition met al complex. The present results from both models indicate that the Mo is the most efficient active site for the dinitrogen binding and reduction among the single transition-met al centers Mo, V and Fe.

Key words: Binding and reduction of dinitrogen, V, Mo, Fe, DFT calculation