Neutral-ligand complexes of bis(imino)pyridine iron: Synthesis, structure, and spectroscopy

Suzanne C. Bart; Emil Lobkovsky; Eckhard Bill; Karl Wieghardt; Paul J. Chirik

doi:10.1021/ic700869h

Neutral-ligand complexes of bis(imino)pyridine iron: Synthesis, structure, and spectroscopy

Suzanne C. Bart, Emil Lobkovsky, Eckhard Bill, Karl Wieghardt, Paul J. Chirik

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105 Scopus citations

Abstract

A family of bis(imino)pyridine iron neutral-ligand derivatives, ( ^iPrPDI)FeL_n (^iPrPDI = 2,6-(2,6- ⁱPr₂-C₆H₃N=CMe)₂C ₆H₃N), has been synthesized from the corresponding bis(dinitrogen) complex, (^iPrPDI)Fe(N₂)₂. When L is a strong-field ligand such as ^tBuNC or a chelating alkyl diphosphine such as DEPE (DEPE = 1,2-bis(diethylphosphino)ethane), a five-coordinate, diamagnetic compound results with no spectroscopic evidence for mixing of paramagnetic states. Reducing the field strength of the neutral donor to principally σ-type ligands such as ^tBuNH₂ or THT (THT = tetrahydrothiophene) also yielded diamagnetic compounds. However, the ¹H NMR chemical shifts of the in-plane bis(imino)pyridine hydrogens exhibit a large chemical shift dispersion indicative of temperature-independent paramagnetism (TIP) arising from mixing of an S = 1 excited state via spin-orbit coupling. Metrical data from X-ray diffraction establish bis(imino)pyridine chelate reduction for each structural type, while Mössbauer parameters and NMR spectroscopic data differentiate the spin states of the iron and identify contributions from paramagnetic excited states.

Original language	English (US)
Pages (from-to)	7055-7063
Number of pages	9
Journal	Inorganic Chemistry
Volume	46
Issue number	17
DOIs	https://doi.org/10.1021/ic700869h
State	Published - Aug 20 2007
Externally published	Yes

All Science Journal Classification (ASJC) codes

Inorganic Chemistry
Physical and Theoretical Chemistry

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title = "Neutral-ligand complexes of bis(imino)pyridine iron: Synthesis, structure, and spectroscopy",

abstract = "A family of bis(imino)pyridine iron neutral-ligand derivatives, ( iPrPDI)FeLn (iPrPDI = 2,6-(2,6- iPr2-C6H3N=CMe)2C 6H3N), has been synthesized from the corresponding bis(dinitrogen) complex, (iPrPDI)Fe(N2)2. When L is a strong-field ligand such as tBuNC or a chelating alkyl diphosphine such as DEPE (DEPE = 1,2-bis(diethylphosphino)ethane), a five-coordinate, diamagnetic compound results with no spectroscopic evidence for mixing of paramagnetic states. Reducing the field strength of the neutral donor to principally σ-type ligands such as tBuNH2 or THT (THT = tetrahydrothiophene) also yielded diamagnetic compounds. However, the 1H NMR chemical shifts of the in-plane bis(imino)pyridine hydrogens exhibit a large chemical shift dispersion indicative of temperature-independent paramagnetism (TIP) arising from mixing of an S = 1 excited state via spin-orbit coupling. Metrical data from X-ray diffraction establish bis(imino)pyridine chelate reduction for each structural type, while M{\"o}ssbauer parameters and NMR spectroscopic data differentiate the spin states of the iron and identify contributions from paramagnetic excited states.",

author = "Bart, {Suzanne C.} and Emil Lobkovsky and Eckhard Bill and Karl Wieghardt and Chirik, {Paul J.}",

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T1 - Neutral-ligand complexes of bis(imino)pyridine iron

T2 - Synthesis, structure, and spectroscopy

AU - Bart, Suzanne C.

AU - Lobkovsky, Emil

AU - Bill, Eckhard

AU - Wieghardt, Karl

AU - Chirik, Paul J.

PY - 2007/8/20

Y1 - 2007/8/20

N2 - A family of bis(imino)pyridine iron neutral-ligand derivatives, ( iPrPDI)FeLn (iPrPDI = 2,6-(2,6- iPr2-C6H3N=CMe)2C 6H3N), has been synthesized from the corresponding bis(dinitrogen) complex, (iPrPDI)Fe(N2)2. When L is a strong-field ligand such as tBuNC or a chelating alkyl diphosphine such as DEPE (DEPE = 1,2-bis(diethylphosphino)ethane), a five-coordinate, diamagnetic compound results with no spectroscopic evidence for mixing of paramagnetic states. Reducing the field strength of the neutral donor to principally σ-type ligands such as tBuNH2 or THT (THT = tetrahydrothiophene) also yielded diamagnetic compounds. However, the 1H NMR chemical shifts of the in-plane bis(imino)pyridine hydrogens exhibit a large chemical shift dispersion indicative of temperature-independent paramagnetism (TIP) arising from mixing of an S = 1 excited state via spin-orbit coupling. Metrical data from X-ray diffraction establish bis(imino)pyridine chelate reduction for each structural type, while Mössbauer parameters and NMR spectroscopic data differentiate the spin states of the iron and identify contributions from paramagnetic excited states.

AB - A family of bis(imino)pyridine iron neutral-ligand derivatives, ( iPrPDI)FeLn (iPrPDI = 2,6-(2,6- iPr2-C6H3N=CMe)2C 6H3N), has been synthesized from the corresponding bis(dinitrogen) complex, (iPrPDI)Fe(N2)2. When L is a strong-field ligand such as tBuNC or a chelating alkyl diphosphine such as DEPE (DEPE = 1,2-bis(diethylphosphino)ethane), a five-coordinate, diamagnetic compound results with no spectroscopic evidence for mixing of paramagnetic states. Reducing the field strength of the neutral donor to principally σ-type ligands such as tBuNH2 or THT (THT = tetrahydrothiophene) also yielded diamagnetic compounds. However, the 1H NMR chemical shifts of the in-plane bis(imino)pyridine hydrogens exhibit a large chemical shift dispersion indicative of temperature-independent paramagnetism (TIP) arising from mixing of an S = 1 excited state via spin-orbit coupling. Metrical data from X-ray diffraction establish bis(imino)pyridine chelate reduction for each structural type, while Mössbauer parameters and NMR spectroscopic data differentiate the spin states of the iron and identify contributions from paramagnetic excited states.

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Neutral-ligand complexes of bis(imino)pyridine iron: Synthesis, structure, and spectroscopy

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