DFT Study on the Mechanism of Iron-Catalyzed Diazocarbonylation

The mechanism of the carbonylation of diazomethane in the presence of iron–carbonyl–phosphine catalysts has been investigated by means of DFT calculations at the M06/def-TZVP//B97D3/def2-TZVP level of theory, in combination with the SMD solvation method. The reaction rate is determined by the formation of the coordinatively unsaturated doublet-state Fe(CO)(3)(P) precursor followed by the diazoalkane coordination and the N(2) extrusion. The free energy of activation is predicted to be 18.5 and 28.2 kcal/mol for the PF(3) and PPh(3) containing systems, respectively. Thus, in the presence of less basic P-donor ligands with stronger [Formula: see text]-acceptor properties, a significant increase in the reaction rate can be expected. According to energy decomposition analysis combined with natural orbitals of chemical valence (EDA–NOCV) calculations, diazomethane in the Fe(CO)(3)(phosphine)(η(1)-CH(2)N(2)) adduct reveals a [Formula: see text]-donor– [Formula: see text]-acceptor type of coordination.