Reaction of iron(II) protoporphyrin IX with the cyano-radical. The structure of pseudohaem

Abstract

Dicyanoiron(II) protoporphyrin IX, when treated with hydrogen peroxide in the presence of ascorbate and cyanide, is known to yield a green compound (pseudohaem). The alternative meso-cyanochlorin structures (Ia), (Ib), or (II) are now proposed for the iron-free derivative of pseudohaem. By adjusting the reaction conditions meso-cyanoprotoporphyrin IX may be isolated. Cyano-free radicals appear to be involved.