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Title: 3D Motions of Iron in Six-Coordinate {FeNO} 7 Hemes by Nuclear Resonance Vibration Spectroscopy [3-D Motions of Iron in Six-coordinate {FeNO} 7 Hemes by NRVS

The vibrational spectrum of a six-coordinate nitrosyl iron porphyrinate, monoclinic [Fe(T pFPP)(1-MeIm)(NO)] (T pFPP = tetra- para-fluorophenylporphyrin; 1-MeIm=1-methylimidazole), has been studied by oriented single-crystal nuclear resonance vibrational spectroscopy (NRVS). The crystal was oriented to give spectra perpendicular to the porphyrin plane and two in-plane spectra perpendicular or parallel to the projection of the FeNO plane. These enable assignment of the FeNO bending and stretching modes. The measurements reveal that the two in-plane spectra have substantial differences that result from the strongly bonded axial NO ligand. The direction of the in-plane iron motion is found to be largely parallel and perpendicular to the projection of the bent FeNO on the porphyrin plane. The out-of-plane Fe-N-O stretching and bending modes are strongly mixed with each other, as well as with porphyrin ligand modes. The stretch is mixed with v 50 as was also observed for dioxygen complexes. The frequency of the assigned stretching mode of eight Fe-X-O (X= N, C, and O) complexes is correlated with the Fe XO bond lengths. The nature of highest frequency band at ≈560 cm -1 has also been examined in two additional new derivatives. Previously assigned as the Fe NO stretch (by resonance Raman), it ismore » better described as the bend, as the motion of the central nitrogen atom of the FeNO group is very large. There is significant mixing of this mode. In conclusion, the results emphasize the importance of mode mixing; the extent of mixing must be related to the peripheral phenyl substituents.« less
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  1. Univ. of Notre Dame, Notre Dame, IN (United States)
  2. Argonne National Lab. (ANL), Argonne, IL (United States)
  3. Northeastern Univ., Boston, MA (United States)
Publication Date:
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Chemistry - A European Journal
Additional Journal Information:
Journal Volume: 22; Journal Issue: 18; Journal ID: ISSN 0947-6539
ChemPubSoc Europe
Research Org:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org:
National Institutes of Health (NIH); National Science Foundation (NSF); USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22), Scientific User Facilities Division; USDOE
Country of Publication:
United States
OSTI Identifier:
Alternate Identifier(s):
OSTI ID: 1400744