10.1021/jacs.7b04552.s002 Demyan E. Prokopchuk Demyan E. Prokopchuk Eric S. Wiedner Eric S. Wiedner Eric D. Walter Eric D. Walter Codrina V. Popescu Codrina V. Popescu Nicholas A. Piro Nicholas A. Piro W. Scott Kassel W. Scott Kassel R. Morris Bullock R. Morris Bullock Michael T. Mock Michael T. Mock Catalytic N<sub>2</sub> Reduction to Silylamines and Thermodynamics of N<sub>2</sub> Binding at Square Planar Fe American Chemical Society 2017 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 00:00:00 Dataset https://acs.figshare.com/articles/dataset/Catalytic_N_sub_2_sub_Reduction_to_Silylamines_and_Thermodynamics_of_N_sub_2_sub_Binding_at_Square_Planar_Fe/5167381 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>.