N-Alkenylporphyrins from the Reaction of DDT with Chloroiron(III) Tetraphenylporphine and Iron Powder

Article abstract of DOI:10.1021/jo00225a065

The reaction of DDT with chloroiron(III) tetraphenylporphine and a large excess of iron powder in 9:1 methylene chloride-methanol produces a mixture of porphyrin products.Demetalation of the product solution under argon yields DDD, tetraphenylporphine, N-<2,2-bis(p-chlorophenyl)ethenyl>tetraphenylporphyrin ("N-vinyl"), and the monocation of N21,N22-<2,2-bis(p-chlorophenyl)ethylidene>tetraphenylporphine ("Rhodo").The alleged "vinylidene carbene" of DDT reported to be generated in this reaction and its reversibly obtained one-electron oxidation product are shown by several means including demetalation and synthesis to be iron(II) and iron(III) complexes of N-vinylporphyrin.The diamagnetic nature of the iron(II) porphyrin(II) porphyrin and, in part, its unusual stability to air are explained by back (?) bonding of the metal to the adjacent olefinic linkage.The iron(III) complex of N-vinyl is converted to the bridged Rhodo porphyrin by Lewis acids and reagents capable of polarizing the nitrogen-bound olefin.