Prokopchuk, Demyan E. Wiedner, Eric S. Walter, Eric D. Popescu, Codrina V. Piro, Nicholas A. Kassel, W. Scott Bullock, R. Morris Mock, Michael T. Catalytic N<sub>2</sub> Reduction to Silylamines and Thermodynamics of N<sub>2</sub> Binding at Square Planar Fe The geometric constraints imposed by a tetradentate P<sub>4</sub>N<sub>2</sub> ligand play an essential role in stabilizing square planar Fe complexes with changes in metal oxidation state. The square pyramidal Fe<sup>0</sup>(N<sub>2</sub>)­(P<sub>4</sub>N<sub>2</sub>) complex catalyzes the conversion of N<sub>2</sub> to N­(SiR<sub>3</sub>)<sub>3</sub> (R = Me, Et) at room temperature, representing the highest turnover number of any Fe-based N<sub>2</sub> silylation catalyst to date (up to 65 equiv N­(SiMe<sub>3</sub>)<sub>3</sub> per Fe center). Elevated N<sub>2</sub> pressures (>1 atm) have a dramatic effect on catalysis, increasing N<sub>2</sub> solubility and the thermodynamic N<sub>2</sub> binding affinity at Fe<sup>0</sup>(N<sub>2</sub>)­(P<sub>4</sub>N<sub>2</sub>). A combination of high-pressure electrochemistry and variable-temperature UV–vis spectroscopy were used to obtain thermodynamic measurements of N<sub>2</sub> binding. In addition, X-ray crystallography, <sup>57</sup>Fe Mössbauer spectroscopy, and EPR spectroscopy were used to fully characterize these new compounds. Analysis of Fe<sup>0</sup>, Fe<sup>I</sup>, and Fe<sup>II</sup> complexes reveals that the free energy of N<sub>2</sub> binding across three oxidation states spans more than 37 kcal mol<sup>–1</sup>. EPR;Fe II complexes;N 2 Binding;tetradentate P 4 N 2 ligand;UV;Fe 0;N 2 binding;Catalytic N 2 Reduction;metal oxidation state;Fe-based N 2 silylation catalyst;N 2 binding affinity;Square Planar Fe;N 2 solubility 2017-06-14
    https://acs.figshare.com/articles/journal_contribution/Catalytic_N_sub_2_sub_Reduction_to_Silylamines_and_Thermodynamics_of_N_sub_2_sub_Binding_at_Square_Planar_Fe/5167384
10.1021/jacs.7b04552.s001