Preparation of Mesoverdohemochrome IXα Dimethyl Ester and Moessbauer Spectra of Related Porphyrins

Article abstract of DOI:10.1246/bcsj.61.3539

Mesobiliverdin IXα dimethyl ester (7) was obtained by hydrogenation of protobiliverdin IXα dimethyl ester (8).Zinc 5-oxamesoporphyrin IX dimethyl ester tetrafluoroborate (6) was prepared by the cyclization of 7 with zinc acetate in acetic anhydride followed by a treatment with aqueous sodium tetrafluoroborate.Bis(pyridine) mesoverdohemochrome IXα dimethyl ester (4) was obtained by the cyclization of 7 with both iron(II) sulfate and iron(III) chloride in acetic anhydride containing a small amount of pyridine.Bis(tosylmethyl isocyanide)mesoverdohemochrome IXα dimethyl ester (5) was prepared by the addition of excess tosylmethyl isocyanide (TsCH2NC) to 4.Both 4 and 5 reacted with ammonia to give iron(III) 5-azamesoporphyrin IX dimethyl ester (10).The Moessbauer spectra of bis(pyridine) verdohemochromes (4, 13, and 14) showed doublet peaks having parameters of δ=0.41-0.43 mm s^-1 and ΔE_Q=1.24-1.26 mm s^-1, indicating that the oxidation states of the central irons of these complexes are iron(II).Bis(TsCH2NC) verdohemochromes (5,15, and 17) showed single peaks having parameters of δ=0.21-0.28 mm s^-1.Unstable intermediate and stable final bis(TsCH2NC) octaethyl verdohemochromes, obtained by the addition of TsCH2NC to 4, were compared with the 1H NMR and Moessbauer spectra.