Sapphyrins: Novel Aromatic Pentapyrrolic Macrocycles
Bauer, V.J., Clive, D.L.J., David Dolphin, Paine, J.B., Harris, F.L., King, M.M., Loder, J., Wang, S.-W.C., and (the late) Woodward, R.B.
J. Am. Chem. Soc
Sapphyrins I (R = Me, R1 = R2 = H; R = R1 = Et, R2 = H; R = R1 = R2 = Me) and sapphyrin-metal complexes II (M = Co, Zn) were prepared. The physical and chemical properties of sapphyrins show them to be aromomatic like porphyrins and corroles. This aromaticity is reflected in the large shielding of the methine and deshielding of the NH protons in the NMR spectra and by their optical spectra, which exhibit Soret and visible bands similar to porphyrins but all bathochromically shifted.