10.1021/om500727t.s001
Jonathan
M. Darmon
Jonathan
M.
Darmon
Renyuan Pony Yu
Renyuan Pony
Yu
Scott P. Semproni
Scott P.
Semproni
Zoë R. Turner
Zoë R.
Turner
S. Chantal E. Stieber
S.
Chantal E. Stieber
Serena DeBeer
Serena
DeBeer
Paul J. Chirik
Paul J.
Chirik
Electronic Structure Determination of Pyridine N‑Heterocyclic
Carbene Iron Dinitrogen Complexes and Neutral Ligand Derivatives
American Chemical Society
2015
Neutral Ligand DerivativesThe
π acceptor
base metal compounds
Electronic Structure Determination
spectroscopic
iron dinitrogen example
chelate
Fe
iPrCNC
DFT
NMR
complex
pyridine
CNC
2015-12-17 05:07:19
Journal contribution
https://acs.figshare.com/articles/journal_contribution/Electronic_Structure_Determination_of_Pyridine_N_Heterocyclic_Carbene_Iron_Dinitrogen_Complexes_and_Neutral_Ligand_Derivatives/2041740
The electronic structures of pyridine
N-heterocyclic dicarbene
(<sup>iPr</sup>CNC) iron complexes have been studied by a combination
of spectroscopic and computational methods. The goal of these studies
was to determine if this chelate engages in radical chemistry in reduced
base metal compounds. The iron dinitrogen example (<sup>iPr</sup>CNC)Fe(N<sub>2</sub>)<sub>2</sub> and the related pyridine derivative (<sup>iPr</sup>CNC)Fe(DMAP)(N<sub>2</sub>) were studied by NMR, Mössbauer,
and X-ray absorption spectroscopy and are best described as redox
non-innocent compounds with the <sup>iPr</sup>CNC chelate functioning
as a classical π acceptor and the iron being viewed as a hybrid
between low-spin Fe(0) and Fe(II) oxidation states. This electronic
description has been supported by spectroscopic data and DFT calculations.
Addition of <i>N</i>,<i>N</i>-diallyl-<i>tert</i>-butylamine to (<sup>iPr</sup>CNC)Fe(N<sub>2</sub>)<sub>2</sub> yielded the corresponding iron diene complex. Elucidation
of the electronic structure again revealed the CNC chelate acting
as a π acceptor with no evidence for ligand-centered radicals.
This ground state is in contrast with the case for the analogous bis(imino)pyridine
iron complexes and may account for the lack of catalytic [2π
+ 2π] cycloaddition reactivity.