期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1978
卷号：75
期号：1
页码：21-25
DOI：10.1073/pnas.75.1.21
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：We have examined the photosensitivity of low-spin liganded hemoglobin, myoglobin, and peroxidase, and their metal-substituted analogues, using three different metals (Fe, Mn, Co) in several oxidation states and employing a variety of diatomic or pseudo-diatomic ligands (L). We have discovered a number of photosensitive systems, and present an overall stereo-electronic classification scheme for these photodissociation reactions: Linear, formally d6, metal-ligand fragments [e.g., Fe(II) +/- CO; Mn(II) +/- NO] are relatively photoliable, but systems with a bent fragment, and higher electron occupancy [e.g., Fe(II) +/- O2; Co(II) +/- NO] are relatively photoinert. Photostability appears to correlate with the occurrence of long-wavelength features in the optical absorption spectra, and the classification scheme is explained by considerations of electronic structure. The discussions are further applied to d5 systems and to low-spin d6 metalloporphyrins with nitrogenous bases as axial ligands.
