DFT Study on the Mechanism of Iron-Catalyzed Diazocarbonylation

Abstract

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 N2 extrusion. The free energy of activation is predicted to be 18.5 and 28.2 kcal/mol for the PF3 and PPh3 containing systems, respectively. Thus, in the presence of less basic P-donor ligands with stronger π-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)(η1-CH2N2) adduct reveals a π-donor–π-acceptor type of coordination.

Comparative Analysis of Nickel–Phosphine Complexes with Cumulated Double Bond Ligands: Structural Insights and Electronic Interactions via ETS-NOCV and QTAIM Approaches

“…The difference in free energy here is 8.4 kcal/mol in favor of the former complex when the two nitrogen atoms are involved in the coordination to the metal center. In our previous studies on nickel-carbonyl [30] and iron-carbonyl-phosphine [31] complexes, no η 2 -(N,N) coordination was predicted; however, κ-N coordination was also found, in contrast with the nickel-phosphine system used in this study.…”

“…Previously, we studied the carbonylation of diazoalkanes in the presence of various cobalt catalysts as well as the mechanism of the reaction [ 27 , 28 , 29 ]. Moreover, the mechanism of diazocarbonylation was scrutinized for the nickel–carbonyl- [ 30 ] and the iron–phosphine–carbonyl- [ 31 ] catalyzed model reactions as well.…”