Generation,
Spectroscopic, and Chemical Characterization
of an Octahedral Iron(V)-Nitrido Species with a Neutral Ligand Platform
Gerard Sabenya
Laura Lázaro
Ilaria Gamba
Vlad Martin-Diaconescu
Erik Andris
Thomas Weyhermüller
Frank Neese
Jana Roithova
Eckhard Bill
Julio Lloret-Fillol
Miquel Costas
10.1021/jacs.7b00429.s002
https://acs.figshare.com/articles/dataset/Generation_Spectroscopic_and_Chemical_Characterization_of_an_Octahedral_Iron_V_-Nitrido_Species_with_a_Neutral_Ligand_Platform/5161396
Iron
complex [Fe<sup>III</sup>(N<sub>3</sub>)(MePy<sub>2</sub>tacn)](PF<sub>6</sub>)<sub>2</sub> (<b>1</b>), containing a neutral triazacyclononane-based
pentadentate ligand, and a terminally bound azide ligand has been
prepared and spectroscopically and structurally characterized. Structural
details, magnetic susceptibility data, and Mössbauer spectra
demonstrate that <b>1</b> has a low-spin (<i>S</i> = 1/2) ferric center. X-ray diffraction analysis of <b>1</b> reveals remarkably short Fe–N (1.859 Å) and long FeN–N<sub>2</sub> (1.246 Å) distances, while the FT-IR spectra show an
unusually low N–N stretching frequency (2019 cm<sup>–1</sup>), suggesting that the FeN–N<sub>2</sub> bond is particularly
weak. Photolysis of <b>1</b> at 470 or 530 nm caused N<sub>2</sub> elimination and generation of a nitrido species that on the basis
of Mössbauer, magnetic susceptibility, EPR, and X-ray absorption
in conjunction with density functional theory computational analyses
is formulated as [Fe<sup>V</sup>(N)(MePy<sub>2</sub>tacn)]<sup>2+</sup> (<b>2</b>). Results indicate that <b>2</b> is a low-spin
(<i>S</i> = 1/2) iron(V) species, which exhibits a short
Fe–N distance (1.64 Å), as deduced from extended X-ray
absorption fine structure analysis. Compound <b>2</b> is only
stable at cryogenic (liquid N<sub>2</sub>) temperatures, and frozen
solutions as well as solid samples decompose rapidly upon warming,
producing N<sub>2</sub>. However, the high-valent compound could be
generated in the gas phase, and its reactivity against olefins, sulfides,
and substrates with weak C–H bonds studied. Compound <b>2</b> proved to be a powerful two-electron oxidant that can add
the nitrido ligand to olefin and sulfide sites as well as oxidize
cyclohexadiene substrates to benzene in a formal H<sub>2</sub>-transfer
process. In summary, compound <b>2</b> constitutes the first
case of an octahedral Fe<sup>V</sup>(N) species prepared within a
neutral ligand framework and adds to the few examples of Fe<sup>V</sup> species that could be spectroscopically and chemically characterized.
2017-06-09 00:00:00
EPR
N 2 elimination
oxidize cyclohexadiene substrates
N 2
X-ray diffraction analysis
triazacyclononane-based pentadentate ligand
FT-IR spectra show
Fe V species
Compound 2
Neutral Ligand Platform Iron
III
X-ray absorption
octahedral Fe V