Hyperfine Shifts of the 13C‐NMR. in Protoporphyrin IX Iron (III) Dicyanide and Deuteroporphyrin IX Iron (III) Dicyanide

The 13C‐NMR. in Zn(II) (Protoporphyrin IX), Fe(III) (Protoporphrin IX) (CN)2, Zn(II) (Deuteroporphyrin IX dimethylester), and Fe(III) (Deuteroporphyrin IX) (CN)2 have been identified, and the 13C hyperfine shifts in the iron complexes evaluated. In a partial analysis of these data the parameters Q H, QCCHH, and QC′CHC, which characterize the isotropic coupling through hyperconjugation between the 1H and 13C nuclei of the porphyrin side chains and the unpaired electron spin density on the aromatic ring carbon atoms, have been re‐examined. This paper is part of an investigation of the electronic states in low spin ferric hemes and hemoproteins, and the relations between the electronic structures and the biological roles of these molecules.