Felix Studt

Theoretical, spectroscopic, and mechanistic studies on transition‐metal dinitrogen complexes: Implications to reactivity and relevance to the nitrogenase problem

Dinitrogen complexes of transition metals exhibit different binding geometries of N2 (end‐on terminal, end‐on bridging, side‐on bridging, side‐on end‐on bridging), which are investigated by spectroscopy and DFT calculations, analyzing their electronic structure and reactivity. For comparison, a bis(μ‐nitrido) complex, where the Nuf8ffN bond has been split, has been studied as well. Most of these systems are highly covalent, and have strong metal–nitrogen bonds. In the present review, particular emphasis is put on a consideration of the activation of the coordinated dinitrogen ligand, making it susceptible to protonation, reactions with electrophiles or cleavage. In this context, theoretical, structural, and spectroscopic data giving informations on the amount of charge on the N2 unit are presented. The orbital interactions leading to a charge transfer from the metals to the dinitrogen ligand and the charge distribution within the coordinated N2 group are analyzed. Correlations between the binding mode and the observed reactivity of N2 are discussed.

N–N splitting of a functionalized µ-η1:η2 coordinated N2 ligand leading to a µ-nitrido µ-imido core: mechanistic insight from DFT

Silylation of a dinuclear tantalum complex containing a side-on end-on coordinated dinitrogen ligand initiates a sequence of reactions ultimately leading to a bis(micro-imido) structure. DFT is employed to determine the energetics of the entire reaction cascade. Particular emphasis is put on the unprecedented N-N cleavage reaction of the functionalized, micro-eta1:eta2 coordinated dinitrogen ligand. A mechanism for this reaction is derived theoretically and the corresponding transition state is determined.

Vibrational and electronic structure of the dinuclear bis(µ-nitrido) vanadium(V) complex [V(N{N″}2)(µ-N)]2: spectroscopic properties of the M2(µ-N)2 diamond core

The vibrational and electronic structure of the bis(mu-nitrido) bridged complex [V(N{N}2)(mu-N)]2 (1) (where [N{N}2](2-)=[(Me3Si)N{CH(2)CH(2)N(SiMe3)}2](2-)) is analyzed. Assignment of the five modes of the V(2)(mu-N)2 core is based on (15)N isotope shifts and a DFT calculation on the calculated structure I which is an exact reproduction of 1. The three Raman active modes of the planar V(2)(mu-N)2 core are found in the Raman spectrum whereas the two IR allowed vibrations are identified in the infrared spectrum. Furthermore, the electronic structure of is described which complements earlier theoretical studies on the reaction pathway leading to 1(V. M. E. Bates, G. K. B. Clentsmith, F. G. N. Cloke, J. C. Green, H. D. L. Jenkin, Chem. Commun., 2000, 927). Based on the MO scheme of I the UV-vis transitions of 1 are assigned.