Low Activation Barriers in N2 Reduction with H2 at Ruthenium Pincer Complexes Induced by Ligand Cooperativity: A Computational Study

摘要: The catalytic reduction of dinitrogen (N2) with dihydrogen (H2) was investigated by means DFT calculations [MN12-L/def2-TZVP(ECP)] using ruthenium pincer complexes the general formula [Ru{4,6-bis(di-tert-butylphosphanyl)dibenzo[b,d]furan}(H)(X)] (X = H, Me, iPr, Br, I). One tBu group one two phosphorus atoms augmented a CH2BH2 to introduce borane moiety that is needed for cooperative stabilization intermediates and transition states. By optimizing representative amount local minima states, it possible identify closed cycles show surprisingly low activation barriers. As an example, X Me after reoptimization in solvent phase (toluene), states maximum height energy profile only 36.2 kcal mol–1 were obtained largest single barrier 29.2 kcal mol–1! It also observed stabilities amide complexes, which occur late cycle, are very pronounced. Accordingly, they contribute overall span (ES) unfavourable way. However, despite this fact, calculated ES I amounts 48.4 indicates clearly computationally guided design process catalyst suitable approach elements structure enables hydrogen-transfer processes comparatively