Magnetic Circular Dichroism Evidence for an Unusual Electronic Structure of a Tetracarbene-Oxoiron(IV) Complex
The result's identifiers
Result code in IS VaVaI
<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F00216208%3A11310%2F16%3A10329519" target="_blank" >RIV/00216208:11310/16:10329519 - isvavai.cz</a>
Result on the web
<a href="http://dx.doi.org/10.1021/jacs.6b07708" target="_blank" >http://dx.doi.org/10.1021/jacs.6b07708</a>
DOI - Digital Object Identifier
<a href="http://dx.doi.org/10.1021/jacs.6b07708" target="_blank" >10.1021/jacs.6b07708</a>
Alternative languages
Result language
angličtina
Original language name
Magnetic Circular Dichroism Evidence for an Unusual Electronic Structure of a Tetracarbene-Oxoiron(IV) Complex
Original language description
In biology, high valent oxo-iron(IV) species have been shown to be pivotal intermediates for functionalization of C-H bonds in the catalytic cycles of a range of O-2-activating iron enzymes. This work details an electronic-structure investigation of [Fe-IV(O)(L-NHC)(NCMe)](2+) (L-NHC = 3,9,14,20-tetraaza-1,6,12,17-tetraazoniapenta-cyclohexacosane-1(23),4,6(26),10,12(25),15,17(24),21-octaene, complex 1) using helium tagging infrared photodissociation (IRPD), absorption, and magnetic circular dichroism (MCD) spectroscopy, coupled with DFT and highly correlated wave function based-multireferenee calculations. The IRPD spectrum of complex 1 reveals the Fe-O- stretching vibration at 832 +/- 3 cm(-1). By analyzing the Franck-Condon progression, we can determine the same vibration occurring at 616 +/- 10 cm(-1) in the E(d(xy) -> d(xz,yz)) excited state. Both values are similar to those measured for [Fe-IV(O)(TMC)(NCMe)](2+) (TMC = 1,4,8,11-tetramethy1-1,4,8,11-tetraazacyclotetradecane). The low-temperature MCD spectra of complex 1 exhibit three pseudo A-term signals around 12 500, 17 000, and 24 300 cm(-1). We can unequivocally assign them to the ligand field transitions of d(xy) -> d(xz,yz), d(xz,yz) -> d(z2), and d(xz,yz) -> d(x2-y2), respectively, through direct calculations of MCD spectra and independent determination of the MCD C-term signs from the corresponding electron donating and accepting orbitals. In comparison with the corresponding transitions observed for [Fe-IV(0) (SR-TPA)(NCMe)](2+) (SR-TPA = tris(3,5-dirnethy14-methoxyp-yridy1-2-methy)amine), the excitations within the (FeO)(2+) core of complex 1 have similar transition energies, whereas the excitation energy for d(xz,yz) -> d(x2-y2) is significantly higher (similar to 12 000 cm-1 for [Fe-IV(O)(SR-TPA)(NCMe)](2+)). Our results thus substantiate that the tetracarbene ligand (L-NHC) of complex 1 does not significantly affect the bonding in the (FeO)(2+) unit but strongly destabilizes the d(x2-y2) orbital
Czech name
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Czech description
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Classification
Type
J<sub>x</sub> - Unclassified - Peer-reviewed scientific article (Jimp, Jsc and Jost)
CEP classification
CC - Organic chemistry
OECD FORD branch
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Result continuities
Project
<a href="/en/project/GA14-20077S" target="_blank" >GA14-20077S: Non-heme iron catalysts: Investigation of reaction mechanisms</a><br>
Continuities
P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)
Others
Publication year
2016
Confidentiality
S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů
Data specific for result type
Name of the periodical
Journal of the American Chemical Society
ISSN
0002-7863
e-ISSN
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Volume of the periodical
138
Issue of the periodical within the volume
43
Country of publishing house
US - UNITED STATES
Number of pages
14
Pages from-to
14312-14325
UT code for WoS article
000387095000029
EID of the result in the Scopus database
2-s2.0-84994357229