The stretching frequency of the iron-carbon bond, v(Fe-CO), is a direct measure of the iron-carbon bond strength when there is no change in the Fe-C-O geometry. Here we report resonance Raman detection of v(Fe-CO) frequencies in the CO complexes of iron (II) alpha, alpha, alpha, alpha-mesotetrakis(o-pivalamidophenyl)porphyrin, FeII(TpivPP), with trans ligands of varying strength: N-methylimidazole (N-MeIm), 1,2-dimethylimidazole (1,2-Me2Im), pyridine (py), and tetrahydrofuran (THF). It was found that the weaker the iron-trans ligand bond, the stronger the iron-carbon bond. Comparisons of sterically hindered (1,2-Me2Im) and unhindered (N-MeIm) bases are of particular interest because of their implication in the phenomenon of hemoglobin cooperativity and the mechanisms of protein control of heme reactivity. While the CO binding affinity of FeII(TpivPP)(1,2-MeIm) is approximately 400 times lower than that of FeII(TpivPP)(N-MeIm), the v(Fe-CO) frequency for the former (at 496 cm-1) is higher than that for the latter (at 489 cm-1). This example shows that the CO binding affinity cannot be directly correlated with the strength of the iron-carbon bond. Comparison of the CO binding to FeII(TpivPP)(THF) and FeII(TpivPP)(N-MeIm) reveals a similar relationship; the v(Fe-CO) frequency (at 527 cm-1) in FeII(TpivPP)(THF)(CO) is 38 cm-1 higher than that in FeII(TpivPP)(N-MeIm)(CO), but the CO binding affinity is lower for the THF complex.
Download full-text PDF |
Source |
|---|---|
| http://dx.doi.org/10.1021/bi00288a005 | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
Revealing the fundamental role of MoO2 in promoting efficient and stable activation of persulfate by iron carbon based catalysts: Efficient Fe2+/Fe3+ cycling to generate reactive species.
Water Res
October 2022
Shandong Key Laboratory of Water Pollution Control and Resource Reuse, Shandong Key Laboratory of Environmental Processes and Health, School of Environmental Science and Engineering, Shandong University, Qingdao 266200, PR China. Electronic address:
Electron-rich iron sites are the main sites for iron-based catalysts to activate persulfate (PS) to generate reactive species, while blocked Fe/Fe cycling usually reduces the catalytic performance of iron-based materials and hinders the generation of reactive species in the reaction. To solve the bottleneck, we synthesized an iron-carbon nanocomposite catalyst loaded with MoO (Fe/Mo-CNs). The promotion of MoO on the Fe/Fe cycle in the system allowed Fe/Mo-CNs to exhibit excellent catalytic performance and environmental adaptability.
View Article and Find Full Text PDFDispersion forces play a role in (MeIPr)Fe([double bond, length as m-dash]NAd)R (Ad = adamantyl; R = Pe, 1-nor) insertions and Fe-R bond dissociation enthalpies (BDEs).
Dalton Trans
May 2018
Department of Chemistry, CASCaM, University of North Texas, Denton, Texas 76201, USA.
The effects of dispersion on migratory insertion reactions and related iron-carbon bond dissociation energies pertaining to (Me2IPr)FeR2 (R = neoPe, 1-nor), and the conversion of (Me2IPr)Fe([double bond, length as m-dash]NAd)R2 to (Me2IPr)Fe{N(Ad}R)R are investigated via calculations and structural comparisons. Dispersion appears to be an underappreciated, major contributor to common structure and reactivity relationships.
View Article and Find Full Text PDFOrganometallic and radical intermediates reveal mechanism of diphthamide biosynthesis.
Science
March 2018
Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853, USA.
Diphthamide biosynthesis involves a carbon-carbon bond-forming reaction catalyzed by a radical S-adenosylmethionine (SAM) enzyme that cleaves a carbon-sulfur (C-S) bond in SAM to generate a 3-amino-3-carboxypropyl (ACP) radical. Using rapid freezing, we have captured an organometallic intermediate with an iron-carbon (Fe-C) bond between ACP and the enzyme's [4Fe-4S] cluster. In the presence of the substrate protein, elongation factor 2, this intermediate converts to an organic radical, formed by addition of the ACP radical to a histidine side chain.
View Article and Find Full Text PDFMethane Activation by Iron-Carbide Cluster Anions FeC6(-).
J Phys Chem Lett
June 2015
†Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Structural Chemistry of Unstable and Stable Species, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China.
Laser-ablation-generated and mass-selected iron-carbide cluster anions FeC6(-) were reacted with CH4 in a linear ion trap reactor under thermal collision conditions. The reactions were characterized by mass spectrometry and density functional theory calculations. Adsorption product of FeC6CH4(-) was observed in the experiments.
View Article and Find Full Text PDFDegradation mechanism of Direct Pink 12B treated by iron-carbon micro-electrolysis and Fenton reaction.
J Environ Sci (China)
December 2013
Department of Environmental Engineering, School of Chemical Engineering and Technology, University of Science and Technology, Anshan 114051, China.
The Direct Pink 12B dye was treated by iron-carbon micro-electrolysis (ICME) and Fenton oxidation. The degradation pathway of Direct Pink 12B dye was inferred by ultraviolet visible (UV-Vis), infrared absorption spectrum (IR) and high performance liquid chromatography-mass spectrometry (HPLC-MS). The major reason of decolorization was that the conjugate structure was disrupted in the iron-carbon micro-electrolysis (ICME) process.
View Article and Find Full Text PDFWant AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!