The thermodynamic stability and kinetic inertness of highly ubiquitous N2
renders the fixation of dinitrogen to more reactive nitrogen compounds a challenging task. The nitrogenase enzymes catalyze N2
fixation in nature at ambient conditions, yet at high energetic cost (16 ATP per N2
), and the industrial Haber-Bosch process consumes about 2 % of the global energy production. Our group examines the activation and functionalization of N2
at mild conditions. We are particularly interested in developing transition metal catalysts that enable the direct transformation of N2
into nitrogen-containing molecules beyond ammonia. This approach aims at bypassing NH3
as an intermediate for both low-valent (e.g. amines, nitriles) and high-valent (e.g. nitro) nitrogen products.
Metal-mediated, full splitting of dinitrogen into nitride complexes is examined as a key step in N2
functionalization. We have developed transition metal platforms (rhenium, molybdenum, tungsten) that form nitride complexes by N2
splitting via an external stimulus, such as reduction, protonation or photolysis. Kinetic examination by spectroscopic, electrochemical and computational methods gave a detailed mechanistic picture for both N2
splitting and reverse nitride coupling.[1,2]
(Electro-)chemical nitride coupling is examined in the context of ammonia oxidation and its use as fuel.
The splitting of N2
into nitrides was exploited to develop quasi-catalytic model cycles for the synthesis of nitrogen compounds directly from N2
. As a recent example, nitriles and amides were obtained via electrochemical reduction, photolytic N2
splitting and thermal N-transfer (Figure 3).
This example also emphasizes the role of the auxiliary ligand in the nitride transfer reaction as a reservoir for 2e–
reduction of the M≡N moiety. This work is supported by a Consolidator Grant of the European Research Council.
 M. G. Scheibel, B. Askevold, F. Heinemann, E. I. Reijerse, B. de Bruin, S. Schneider, "Closed-Shell and Open-Shell, square-planar Iridium Nitrido Complexes", Nature Chem 2012, 4, 552.
 B. M. Lindley, R. S. van Alten, M. Finger, F. Schendzielorz, C. Würtele, A. J. M. Miller, I. Siewert, S. Schneider, "Mechanism of Chemical and Electrochemical N2 Splitting by a Rhenium Pincer Complex", J. Am. Chem. Soc., 2018, 140, 7922-7935.
 F. Schendzielorz, M. Finger, J. Abbenseth, C. Würtele, V. Krewald, S. Schneider, "Metal-Ligand Cooperative Synthesis of Benzonitrile via Electrochemical Reduction and Photolytic Splitting of Dinitrogen", Angew. Chem. Int. Ed., 2019, 58, 830-834.