SUBSTITUTED DEUTEROPORPHYRINS .6. LIGAND-EXCHANGE AND DIMERIZATION REACTIONS OF DEUTEROHEMINS

Ligand-exchange and dimerization reactions of deuteroporphyrin IX dimethyl ester iron(III)derivatives (deuterohemins) were explored. Ligand-exchange reactions of the acetatodeuterohemin were used to prepare solid monomeric fluoro-, chloro-, bromo-, iodo-, azido-, phenoxo-, and hypophosphitodeuterohemins, which were characterized by elemental analyses, infrared spectra, mass spectra, and molecular weight. Aquation reactions of the deuterohemins, and also autoxidation of deuteroheme, gave a product characterized as a dimer with an Fe-O-Fe linkage. Isotopic substitution with 18O provided strong infrared evidence for such a linkage. Mossbauer parameters were also determined. These data suggest dimers of this type may be encountered frequently in hemins and also incertain hemeproteins (e.g., cytochrome oxidase). Also considered are mechanisms for ligand exchangeand dimerization which involve doubly bridged dimeric structures. © 1969, American Chemical Society. All rights reserved.