A new route to thiocarbonyl-iron complexes: Preparation of FeII[porphyrin][C(Cl)SR] carbene complexes and their conversion to FeII[porphyrin][CS] complexes

Article abstract of DOI:10.1021/ic00135a066

The reaction of trichloromethyl-thioalkyl compounds including the widely used fungicides Captan and Folpet with iron(II) porphyrins in the presence of a reducing agent in excess leads to the formation of new carbene complexes, Fe[porphyrin][C(Cl)SR], whose stabilities are strongly dependent on the nature of the R substituent. Upon treatment by a catalytic amount of FeCl₂ or CuCl₂, some of them are decomposed into thiocarbonyliron(II)-porphyrin complexes, Fe[porphyrin][CS], in nearly quantitative yields. Various Fe[porphyrin][CS][L] complexes have thus been obtained by this method and characterized by UV-visible, IR, and ¹H and ¹³C NMR spectroscopy. They are very stable to dioxygen and nucleophiles but react with primary amines R′NH₂ in excess to give the Fe[porphyrin][CNR′][R′NH₂] complexes. Reduction of C₆H₅SCHCl₂ by iron(II) tetraphenylporphyrin, Fe[TPP], leads to the Fe[TPP][CHSC₆H₅] complex, which is the first example of an iron(II) porphyrin complex bearing a secondary CHR carbene.