End-on terminal reduction pathway

Electronic Structure and Spectroscopic Properties of Molybdenum and Tungsten N2, NNH, NNH2, and NNH3 Complexes with Diphosphine Co-Ligands Insights into the End-on Terminal Reduction Pathway of Di nitrogen Felix Tuczek... 

ELECTRONIC STRUCTURE AND SPECTROSCOPIC PROPERTIES OF MOLYBDENUM AND TUNGSTEN N2, NNH, NNH2i AND NNH3 COMPLEXES WITH DIPHOSPHINE CO-LIGANDS INSIGHTS INTO THE END-ON TERMINAL REDUCTION PATHWAY OF DINITROGEN... 

Lehnert and Tuczek further studied end-on terminal coordination by density functional theory (DFT) calculations on the compounds [Mo(N2)2(dppe)2], [MoF(NNH)(dppe)2], and [MoF(NNH2)(dppe)2]+, where dppe= 1,2-bis(diphenyl-phosphino)ethane.50 They proposed a reaction scheme, shown in reaction 6.13, for asymmetric dinitrogen reduction and protonation. The end-on model favored by Lehnert in reference 50, as shown in reaction 6.13, appears to be a less thermodynamically unfavorable pathway, at least to reach the M-NNH3 intermediate. Step 1 produces a metal-attached diazenido ion (NNH-), step 2 produces a hydrazido ion (NNH2 ), and step 3 produces a hydrazidium ion (NNHj). 

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