A Mechanistic Investigation Into the Photochemistry of an Iron(0) Complex in C-Cl, C-H, and C-F Bond Activation

Abstract

The photochemical generation of an Fe(0) model complex and its subsequent reactivity with C-Cl and C-F bonds was investigated in this work. The photochemical generation and ultrafast dynamics of the Fe(0) model complex was studied. The rate of H₂ escape in solvents of various viscosities, as well as the effect of H₂ versus D₂ release, was also investigated, as was the yield of geminate recombination of the Fe(0) complex and H₂ within the solvent cage. The photochemically generated Fe(0) species was then studied for its ability to dechlorinate CE substrates. A mechanistic investigation was conducted, and a hydrogenolysis pathway was observed. Additionally, increased chlorination of the CE substrates was observed to lead to faster rates of dechlorination by the Fe(0) system. C-F activation of fluorobenzene substrates by the parent Fe(II) complex was evaluated, and activation of the C-F bond was proposed to occur via electron transfer within the solvent cage. Competitive C-H activation of nonperfluorinated substrates was observed when light was introduced into the system, similar to the oxidative addition mechanism mediated by the previously investigated Fe(0) species.