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Title: Interplay of structure and vibrational dynamics in six-coordinate heme nitrosyls.

Abstract

The isolation of two polymorphic forms of nitrosyl(1-methylimidazole)(tetra-p-fluorophenylporphinato)iron(II) provides a unique opportunity to explore the interplay of structure and vibrational dynamics in six-coordinate {l_brace}FeNO{r_brace}{sup 7} nitrosyliron porphyrinates. The two species display differing vibrational spectroscopic properties both in {nu}{sub NO} (IR) and the iron vibrational modes obtained through the use of nuclear resonance vibrational spectroscopy. Structural characterization of the two complexes has yielded extremely high-quality structures that further confirm that coordination of NO leads to ligand tilting and asymmetry in the equatorial Fe-Np bond distances. The two polymorphic structures (monoclinic and triclinic crystal systems) differ in the relative orientations of the two axial ligands and small but significant differences in coordination group bond distances. Although DFT calculations suggest that the NO/imidazole orientations should be indistinguishable, real experimental (structural and vibrational) differences between the two are found. The observed variation in the axial and equatorial Fe-N bonds is strongly correlated to the dynamics of the Fe-NO unit and other motions of iron. Other structural differences appear to have little effect on the vibrational properties of the two forms. The in-plane motions of iron in CO versus NO heme complexes illustrate distinct dynamic differences.

Authors:
; ; ; ; ; ; ; ; ; ;
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
USDOE Office of Science (SC); National Institutes of Health (NIH)
OSTI Identifier:
914977
Report Number(s):
ANL/XSD/JA-58813
TRN: US200817%%45
DOE Contract Number:  
DE-AC02-06CH11357
Resource Type:
Journal Article
Resource Relation:
Journal Name: J. Am. Chem. Soc. Commun.; Journal Volume: 129; Journal Issue: 8 ; Feb. 2, 2007
Country of Publication:
United States
Language:
ENGLISH
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; HEME; IRON COMPLEXES; NITROSO COMPOUNDS; MORPHOLOGY; VIBRATIONAL STATES; PORPHYRINS; NITRIC OXIDE; IMIDAZOLES; DENSITY FUNCTIONAL METHOD

Citation Formats

Silvernail, N. J., Barabanschikov, A., Pavlik, J. W., Noll, B. C., Zhao, J., Alp, E. E., Sturhahn, W., Stage, J. T., Scheidt, W. R., Univ. of Notre Dame, and Notheastern Univ. Interplay of structure and vibrational dynamics in six-coordinate heme nitrosyls.. United States: N. p., 2007. Web. doi:10.1021/ja066869k.
Silvernail, N. J., Barabanschikov, A., Pavlik, J. W., Noll, B. C., Zhao, J., Alp, E. E., Sturhahn, W., Stage, J. T., Scheidt, W. R., Univ. of Notre Dame, & Notheastern Univ. Interplay of structure and vibrational dynamics in six-coordinate heme nitrosyls.. United States. doi:10.1021/ja066869k.
Silvernail, N. J., Barabanschikov, A., Pavlik, J. W., Noll, B. C., Zhao, J., Alp, E. E., Sturhahn, W., Stage, J. T., Scheidt, W. R., Univ. of Notre Dame, and Notheastern Univ. Fri . "Interplay of structure and vibrational dynamics in six-coordinate heme nitrosyls.". United States. doi:10.1021/ja066869k.
@article{osti_914977,
title = {Interplay of structure and vibrational dynamics in six-coordinate heme nitrosyls.},
author = {Silvernail, N. J. and Barabanschikov, A. and Pavlik, J. W. and Noll, B. C. and Zhao, J. and Alp, E. E. and Sturhahn, W. and Stage, J. T. and Scheidt, W. R. and Univ. of Notre Dame and Notheastern Univ.},
abstractNote = {The isolation of two polymorphic forms of nitrosyl(1-methylimidazole)(tetra-p-fluorophenylporphinato)iron(II) provides a unique opportunity to explore the interplay of structure and vibrational dynamics in six-coordinate {l_brace}FeNO{r_brace}{sup 7} nitrosyliron porphyrinates. The two species display differing vibrational spectroscopic properties both in {nu}{sub NO} (IR) and the iron vibrational modes obtained through the use of nuclear resonance vibrational spectroscopy. Structural characterization of the two complexes has yielded extremely high-quality structures that further confirm that coordination of NO leads to ligand tilting and asymmetry in the equatorial Fe-Np bond distances. The two polymorphic structures (monoclinic and triclinic crystal systems) differ in the relative orientations of the two axial ligands and small but significant differences in coordination group bond distances. Although DFT calculations suggest that the NO/imidazole orientations should be indistinguishable, real experimental (structural and vibrational) differences between the two are found. The observed variation in the axial and equatorial Fe-N bonds is strongly correlated to the dynamics of the Fe-NO unit and other motions of iron. Other structural differences appear to have little effect on the vibrational properties of the two forms. The in-plane motions of iron in CO versus NO heme complexes illustrate distinct dynamic differences.},
doi = {10.1021/ja066869k},
journal = {J. Am. Chem. Soc. Commun.},
number = 8 ; Feb. 2, 2007,
volume = 129,
place = {United States},
year = {Fri Feb 02 00:00:00 EST 2007},
month = {Fri Feb 02 00:00:00 EST 2007}
}