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Abstract 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 and15N labeling allowed for the first15N 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.
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TMEDA in Iron‐Catalyzed Hydromagnesiation: Formation of Iron(II)‐Alkyl Species for Controlled Reduction to Alkene‐Stabilized Iron(0)
Abstract N,N,N′,N′‐Tetramethylethylenediamine (TMEDA) has been one of the most prevalent and successful additives used in iron catalysis, finding application in reactions as diverse as cross‐coupling, C−H activation, and borylation. However, the role that TMEDA plays in these reactions remains largely undefined. Herein, studying the iron‐catalyzed hydromagnesiation of styrene derivatives using TMEDA has provided molecular‐level insight into the role of TMEDA in achieving effective catalysis. The key is the initial formation of TMEDA–iron(II)–alkyl species which undergo a controlled reduction to selectively form catalytically active styrene‐stabilized iron(0)–alkyl complexes. While TMEDA is not bound to the catalytically active species, these active iron(0) complexes cannot be accessed in the absence of TMEDA. This mode of action, allowing for controlled reduction and access to iron(0) species, represents a new paradigm for the role of this important reaction additive in iron catalysis.
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- Award ID(s):
- 1725028
- PAR ID:
- 10236606
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Angewandte Chemie International Edition
- Volume:
- 59
- Issue:
- 39
- ISSN:
- 1433-7851
- Page Range / eLocation ID:
- p. 17070-17076
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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