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Title: Comprehensive Fe-ligand vibration identification in {FeNO}6 Hemes

Oriented single-crystal nuclear resonance vibrational spectroscopy (NRVS) has been used to obtain all iron vibrations in two {FeNO}6 porphyrinate complexes, five-coordinate [Fe(OEP)(NO)]ClO4 and six-coordinate [Fe(OEP)(2-MeHIm)(NO)]ClO4. A new crystal structure was required for measurements of [Fe(OEP)(2-MeHIm)(NO)]ClO4, and the new structure is reported herein. Single crystals of both complexes were oriented to be either parallel or perpendicular to the porphyrin plane and/or axial imidazole ligand plane. Thus, the FeNO bending and stretching modes can now be unambiguously assigned; the pattern of shifts in frequency as a function of coordination number can also be determined. The pattern is quite distinct from those found for CO or {FeNO}7 heme species. This is the result of unchanging Fe–NNO bonding interactions in the {FeNO}6 species, in distinct contrast to the other diatomic ligand species. DFT calculations were also used to obtain detailed predictions of vibrational modes. Predictions were consistent with the intensity and character found in the experimental spectra. The NRVS data allow the assignment and observation of the challenging to obtain Fe–Im stretch in six-coordinate heme derivatives. Furthermore, NRVS data for this and related six-coordinate hemes with the diatomic ligands CO, NO, and O2 reveal a strong correlation between the Fe–Im stretch and Fe–NIm bondmore » distance that is detailed for the first time.« less
Authors:
 [1] ;  [2] ;  [2] ;  [3] ;  [3] ;  [3] ;  [4] ;  [2]
  1. Univ. of Chinese Academy of Sciences, Beijing (China); Univ. of Notre Dame, Notre Dame, IN (United States)
  2. Univ. of Notre Dame, Notre Dame, IN (United States)
  3. Argonne National Lab. (ANL), Argonne, IL (United States)
  4. Northeastern Univ., Boston, MA (United States)
Publication Date:
OSTI Identifier:
1240885
Grant/Contract Number:
AC02-06CH11357
Type:
Accepted Manuscript
Journal Name:
Journal of the American Chemical Society
Additional Journal Information:
Journal Volume: 136; Journal Issue: 52; Journal ID: ISSN 0002-7863
Publisher:
American Chemical Society (ACS)
Research Org:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org:
USDOE Office of Science (SC)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY