The effect of axial ligand plane orientation on the isotopic shifts of the dichelated protohemin cyanide complexes of Traylor and Berzinis

The effect of axial ligand plane orientation on the isotropic shifts of the dichelated protohemin cyanide complexes of T.G. Traylor and A.P. Berzinis, who published the NMR spectrum of the mixture of two geometrical isomers in 1980. It was one of the first proofs of dependence of heme methyl shifts on the orientation of planar axial ligands. Now the (super.1)H NMR spectra have been investigated using 1- and 2D NMR techniques and the majority of the resonances have been assigned, with the exception of some of the meso-H resonances and those of the CH(sub.2) protons beyond the beta-CH(sub.2) of the 6- and 7-propionamides of each isomer. Each isomer has four widely separated methyl resonances, the order and spread of chemical shifts of which is consistent with predictions.