The variation in the recovery time of transient ADC decreases in the ischemic periphery reflects the gradient of the tissue perfusion. Severely delayed recovery time after spreading depression is thought to represent the ischemic penumbra.
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 Mössbauer spectra of bis(pyridine) verdohemochromes (4, 13, and 14) snowed doublet peaks having parameters of δ=0.41–0.43 mm s−1 and ΔEQ=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 Mössbauer spectra.
In order to study the valence state in the mixed-valence binuclear ferrocenes, X-ray absorption spectra near the Fe K-edge were measured using synchrotron radiation. Well-resolved lines in the spectra obtained for ferrocene derivatives were assigned to the 1s→3d, 1s→Cp(π*), and 1s→4p transitions, respectively, based on the molecular orbitals. There is an apparent difference in the 1s→3d transitions between trapped-valence compounds and averaged-valence compounds in the I3− salts of the monocation of binuclear ferrocenes. The valence states of the mixed-valence binuclear ferrocenes were also studied by X-ray photoelectron spectroscopy.
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