One Electron Makes Differences: From Heme {FeNO}7 to {FeNO}8 |
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| Authors: | Bin Hu Prof Jianfeng Li |
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| Institution: | College of Materials Science and Opto‐electronic Technology, University of Chinese Academy of Sciences, Yanqi Lake, Huairou District, Beijing, 101408 (China) |
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| Abstract: | The first X‐ray single‐crystal structure of a {FeNO}8 porphyrin complex Co(Cp)2]Fe(TFPPBr8)(NO)], and the structure of the {FeNO}7 precursor Fe(TFPPBr8)(NO)] are determined at 100 K. The two complexes are also characterized by FTIR and UV/Vis spectroscopy. Fe(TFPPBr8)(NO)]? shows distinct structural features in contrast to a nitrosyl iron(II) porphyrinate on the Fe? N? O? moiety, which include a much more bent Fe? N? O? angle (122.4(3)°), considerably longer Fe? NO? (1.814(4)) and N? O? (1.194(5) Å) bond distances. These and the about 180 cm?1 downshift νN‐O stretch (1540 cm?1) can be understood by the covalently bonding nature between the iron(II) and the NO? ligand which possesses a two‐electron‐occupied π* orbital as a result of the reduction. The overall structural features of Fe(TFPPBr8)(NO)]? and Fe(TFPPBr8)(NO)] suggest a low‐spin state of the iron(II) atom at 100 K. |
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| Keywords: | crystal structure iron enzymes porphyrins X‐ray diffraction |
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