A great advantage of the Evans (1) nmr method for the determination of magnetic susceptibility is that measurements are made on the solution phase and thereby supplement the solid state measurements made by the Gouy and Faraday techniques.

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proteins is not probable unless the protein were attached to a pyrrole ring rather than being coordinated to iron(III).Acknowledgments. This investigation was supported in part by a grant from the Research Corporation. We are grateful to Barney Nist, University of Washington, for measuring the temperature-dependent nmr spectra and Professor G. Gerhold for supplying the computer program. We also thank Professor W. S. Caughey for helpful discussions.Characterization of a d7 Iron System.

The last few years have seen substantial growth in metalloporphyrin research. Certainly most of this stems from interest in the biological systems to which these compounds are related. However metalloporphyrins are also studied for other reasons. These include the search for new semiconductors,1 superconductors,2 anticancer drugs,3 and catalysts.4Several porphyrin-related compounds, particularly the phthalocyanines,5 have proved useful as dyes.Even without their biological and industrial implications the properties of metalloporphyrins would be studied for their purely theoretical importance. Thus, even to the nonspecialist, a knowledge of the more recent or unusual synthetic metalloporphyrins could be useful.The porphyrins are compounds formed by adding substituents to the nucleus of porphine (1). The nat-R5 Rh r4 1 urally occurring porphyrins are generally formed by adding substituents to positions 1-8 and are named according to the number and type of substituents. The roman numerals after the name indicate the pattern of substitution. Of the large number of possible arrangements, few have been found in nature. Table I lists several porphyrins, both natural and synthetic, along with their trivial names. Certain common porphyrins will hereafter be referred to by abbreviations listed in Table I.Upon removal of the pyrrole protons, porphyrins readily complex with a variety of metals. While free David Ostfeld was born in Chicago in 1942. He earned his B.S. in Chemistry from the University of Illinois and his Ph.D. from Cornell Uniersity. Three years of postdoctoral work, including a year with Professor Tsutsui, were devoted to studying metalloporphyrin chemistry. Currently he is