Unprecedented Five‐Coordinate Iron(IV) Imides Generate Divergent Spin States Based on the Imide R‐Groups

Three five‐coordinate iron(IV) imide complexes have been synthesized and characterized. These novel structures have disparate spin states on the iron as a function of the R‐group attached to the imide, with alkyl groups leading to low‐spin diamagnetic (S=0) complexes and an aryl group leading to an...

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Bibliographic Details
Published in:Angewandte Chemie International Edition 2019-06, Vol.58 (24), p.8115-8118
Main Authors: Anneser, Markus R., Elpitiya, Gaya R., Townsend, Jacob, Johnson, Elizabeth J., Powers, Xian B., DeJesus, Joseph F., Vogiatzis, Konstantinos D., Jenkins, David M.
Format: Article
Language:English
Subjects:
Aromatic compounds
Bonding
Coordination compounds
Diamagnetism
Imides
Iron
macrocycles
Mossbauer spectroscopy
N-heterocyclic carbenes
NMR
Nuclear magnetic resonance
organometallic chemistry
Oxidation
Valence
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Summary:Three five‐coordinate iron(IV) imide complexes have been synthesized and characterized. These novel structures have disparate spin states on the iron as a function of the R‐group attached to the imide, with alkyl groups leading to low‐spin diamagnetic (S=0) complexes and an aryl group leading to an intermediate‐spin (S=1) complex. The different spin states lead to significant differences in the bonding about the iron center as well as the spectroscopic properties of these complexes. Mössbauer spectroscopy confirmed that all three imide complexes are in the iron(IV) oxidation state. The combination of diamagnetism and 15N labeling allowed for the first 15N NMR resonance recorded on an iron imide. Multi‐reference calculations corroborate the experimental structural findings and suggest how the bonding is distinctly different on the imide ligand between the two spin states. Three five‐coordinate iron(IV) imide complexes were synthesized and characterized. These structures have disparate spin states on the iron as a function of the R‐group attached to the imide, with alkyl groups leading to low‐spin diamagnetic (S=0) complexes and an aryl group giving an intermediate‐spin (S=1) complex.
ISSN:1433-7851
1521-3773
DOI:10.1002/anie.201903132