High-spin iron(III) tetramethylchiroporphyrins: structural, magnetic, and 1H NMR studies

The chloroiron(III) complex of alpha-beta-alpha-beta-tetramethylchiroporphyrin, FeCl(TMCP), was synthesized and structurally characterized. The structure has a unique five-coordinate high-spin iron(III) center in a strongly ruffled and domed porphyrin, with short equatorial distances and the iron 0.64 angstrom out of the porphyrin mean plane toward the chlorine atom. The pyrrole proton resonances are shifted downfield to 80-100 ppm at 293 K, more than in the corresponding tetraaryl derivatives.