Journal
INORGANIC CHEMISTRY
Volume 39, Issue 22, Pages 5102-5110Publisher
AMER CHEMICAL SOC
DOI: 10.1021/ic000789e
Keywords
-
Categories
Funding
- NCRR NIH HHS [RR-06709] Funding Source: Medline
- NIGMS NIH HHS [GM-38401] Funding Source: Medline
Ask authors/readers for more resources
The synthesis and crystallographic characterization of the five-coordinate iron(III) porphyrinate complex [Fe-(OEP)(NO)]ClO4 are reported. This {FeNO}(6) complex has a nearly linear Fe-N-O group (angle = 173.19-(13)degrees) with a small off-axis tilt of the Fe-N(NO) vector from the heme normal (angle = 4.6 degrees); the Fe-N(NO) distance is 1.6528(13) Angstrom and the iron is displaced 0.32 Angstrom out-of-plane. The complex forms a tight cofacial pi-pi dimer in the solid state. Mossbauer spectra for this derivative as well as for a related crystalline form are measured both in zero applied magnetic field and in a 7 T applied field. Fits to the measurements made in applied magnetic field demonstrate that both crystalline forms of [Fe(OEP)(NO)]ClO4 have a diamagnetic ground slate at 4.2 K. The observed isomer shifts (delta = 0.22-0.24 mm/s) are smaller than those typically observed for low-spin iron(III) porphyrinates. Analogous Mossbauer measurements are also obtained for a six-coordinate derivative, [Fe-(OEP)(Iz)(NO)]ClO4 (Iz = indazole). The observed isomer shift for this species is smaller still (delta = 0.02 mm/s). All derivatives show a strong temperature dependence of the isomer shift. The data emphasize the strongly covalent nature of the FeNO group. The Mossbauer isomer shifts suggest formal oxidation states greater than +3 for iron, but the NO stretching frequencies are not consistent with such a large charge transfer to NO. Differences in the observed nitrosyl stretching frequencies of the two crystalline forms of [Fe(OEP)(NO)]ClO4 are discussed.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available