Structural and physical properties of delocalized mixed-valent [Cp*M(pentalene)M′Cp*]n+ and [Cp*M(indacene)M′Cp*]n+ (M, M′ = Fe, Co, Ni; n = 0, 1, 2) complexes

Juan M. Manriquez, Michael Ward, William M. Reiff, Joseph C. Calabrese, Nancy L. Jones, Patrick J. Carroll, Emilio E. Bunel, Joel S. Miller

Research output: Contribution to journalArticle

Abstract

The structural characterization and physical properties of [Cp*M(pentalene)M′Cp*]n+ (Cp* = pentamethylcyclopentadiene; M, M′ = Fe, Fe (1a); Co, Co (1b); Ni, Ni (1c); Ru, Ru (1d); Fe, Ru (1e); Fe, Co (1f); n = 0, 1, 2) and [Cp*M(s-indacene)M′Cp*]n+ (s = symmetric) and [Cp*M(as-indacene)M′Cp*]n+ (M, M′ = Fe, Fe (2a, 3a); Co, Co (2b, 3b); Ni, Ni (2c, 3c); n = 0, 1, 2) (as = asymmetric) are reported. The local molecular structure of the organometallic complex does not change significantly with oxidation state; in all cases the Cp*M moieties reside on opposite faces of the fused μ-bridging ring systems, reflecting the dominance of steric effects. These complexes generally exhibit behavior consistent with significant electronic interactions between metal centers, including large electrochemical potential separations between successive one-electron redox events, and for the mixed valent (n = 1+) complexes, intervalent charge transfer absorption bands. The magnetic susceptibility data are consistent with intramolecular ferromagnetic coupling of spins for 1a2+ and 2c2+ and antiferromagnetic coupling of spins for 1c, 1c2+, 1b, 2b, 1c+, 2c+, and 3c+. In general, the paramagnetic complexes exhibit Curie-Weiss behavior, except for 2c and 3c, which possess singlet ground states and high spin excited states that are 0.036 and 0.056 eV (290 and 524 cm-1) above the ground state, respectively. Mixed-valent 1a+ and 2a+ are fully detrapped on the Mössbauer time scale (i.e., electron transfer rates ≥107 s-1) above 1.5 K, consistent with a negligible energy barrier to intramolecular electron transfer or complete delocalization. The EPR spectra of 1a+, 2a+, and 1e+ exhibit significantly reduced g-factor ansiotropies and more intense spectral features at ambient temperature compared to [FeCp*2]•+, implying intramolecular electron transfer rates ≥1010 s-1.

Original languageEnglish (US)
Pages (from-to)6182-6192
Number of pages11
JournalJournal of the American Chemical Society
Volume117
Issue number23
StatePublished - Jun 14 1995

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Structural properties
Physical properties
Electrons
Ground state
Energy barriers
Organometallics
Molecular Structure
Magnetic susceptibility
Excited states
Molecular structure
Oxidation-Reduction
Paramagnetic resonance
Charge transfer
Absorption spectra
Metals
Oxidation
Temperature

ASJC Scopus subject areas

  • Chemistry(all)

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Structural and physical properties of delocalized mixed-valent [Cp*M(pentalene)M′Cp*]n+ and [Cp*M(indacene)M′Cp*]n+ (M, M′ = Fe, Co, Ni; n = 0, 1, 2) complexes. / Manriquez, Juan M.; Ward, Michael; Reiff, William M.; Calabrese, Joseph C.; Jones, Nancy L.; Carroll, Patrick J.; Bunel, Emilio E.; Miller, Joel S.

In: Journal of the American Chemical Society, Vol. 117, No. 23, 14.06.1995, p. 6182-6192.

Research output: Contribution to journalArticle

Manriquez, Juan M. ; Ward, Michael ; Reiff, William M. ; Calabrese, Joseph C. ; Jones, Nancy L. ; Carroll, Patrick J. ; Bunel, Emilio E. ; Miller, Joel S. / Structural and physical properties of delocalized mixed-valent [Cp*M(pentalene)M′Cp*]n+ and [Cp*M(indacene)M′Cp*]n+ (M, M′ = Fe, Co, Ni; n = 0, 1, 2) complexes. In: Journal of the American Chemical Society. 1995 ; Vol. 117, No. 23. pp. 6182-6192.
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title = "Structural and physical properties of delocalized mixed-valent [Cp*M(pentalene)M′Cp*]n+ and [Cp*M(indacene)M′Cp*]n+ (M, M′ = Fe, Co, Ni; n = 0, 1, 2) complexes",
abstract = "The structural characterization and physical properties of [Cp*M(pentalene)M′Cp*]n+ (Cp* = pentamethylcyclopentadiene; M, M′ = Fe, Fe (1a); Co, Co (1b); Ni, Ni (1c); Ru, Ru (1d); Fe, Ru (1e); Fe, Co (1f); n = 0, 1, 2) and [Cp*M(s-indacene)M′Cp*]n+ (s = symmetric) and [Cp*M(as-indacene)M′Cp*]n+ (M, M′ = Fe, Fe (2a, 3a); Co, Co (2b, 3b); Ni, Ni (2c, 3c); n = 0, 1, 2) (as = asymmetric) are reported. The local molecular structure of the organometallic complex does not change significantly with oxidation state; in all cases the Cp*M moieties reside on opposite faces of the fused μ-bridging ring systems, reflecting the dominance of steric effects. These complexes generally exhibit behavior consistent with significant electronic interactions between metal centers, including large electrochemical potential separations between successive one-electron redox events, and for the mixed valent (n = 1+) complexes, intervalent charge transfer absorption bands. The magnetic susceptibility data are consistent with intramolecular ferromagnetic coupling of spins for 1a2+ and 2c2+ and antiferromagnetic coupling of spins for 1c, 1c2+, 1b, 2b, 1c+, 2c+, and 3c+. In general, the paramagnetic complexes exhibit Curie-Weiss behavior, except for 2c and 3c, which possess singlet ground states and high spin excited states that are 0.036 and 0.056 eV (290 and 524 cm-1) above the ground state, respectively. Mixed-valent 1a+ and 2a+ are fully detrapped on the M{\"o}ssbauer time scale (i.e., electron transfer rates ≥107 s-1) above 1.5 K, consistent with a negligible energy barrier to intramolecular electron transfer or complete delocalization. The EPR spectra of 1a+, 2a+, and 1e+ exhibit significantly reduced g-factor ansiotropies and more intense spectral features at ambient temperature compared to [FeCp*2]•+, implying intramolecular electron transfer rates ≥1010 s-1.",
author = "Manriquez, {Juan M.} and Michael Ward and Reiff, {William M.} and Calabrese, {Joseph C.} and Jones, {Nancy L.} and Carroll, {Patrick J.} and Bunel, {Emilio E.} and Miller, {Joel S.}",
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T1 - Structural and physical properties of delocalized mixed-valent [Cp*M(pentalene)M′Cp*]n+ and [Cp*M(indacene)M′Cp*]n+ (M, M′ = Fe, Co, Ni; n = 0, 1, 2) complexes

AU - Manriquez, Juan M.

AU - Ward, Michael

AU - Reiff, William M.

AU - Calabrese, Joseph C.

AU - Jones, Nancy L.

AU - Carroll, Patrick J.

AU - Bunel, Emilio E.

AU - Miller, Joel S.

PY - 1995/6/14

Y1 - 1995/6/14

N2 - The structural characterization and physical properties of [Cp*M(pentalene)M′Cp*]n+ (Cp* = pentamethylcyclopentadiene; M, M′ = Fe, Fe (1a); Co, Co (1b); Ni, Ni (1c); Ru, Ru (1d); Fe, Ru (1e); Fe, Co (1f); n = 0, 1, 2) and [Cp*M(s-indacene)M′Cp*]n+ (s = symmetric) and [Cp*M(as-indacene)M′Cp*]n+ (M, M′ = Fe, Fe (2a, 3a); Co, Co (2b, 3b); Ni, Ni (2c, 3c); n = 0, 1, 2) (as = asymmetric) are reported. The local molecular structure of the organometallic complex does not change significantly with oxidation state; in all cases the Cp*M moieties reside on opposite faces of the fused μ-bridging ring systems, reflecting the dominance of steric effects. These complexes generally exhibit behavior consistent with significant electronic interactions between metal centers, including large electrochemical potential separations between successive one-electron redox events, and for the mixed valent (n = 1+) complexes, intervalent charge transfer absorption bands. The magnetic susceptibility data are consistent with intramolecular ferromagnetic coupling of spins for 1a2+ and 2c2+ and antiferromagnetic coupling of spins for 1c, 1c2+, 1b, 2b, 1c+, 2c+, and 3c+. In general, the paramagnetic complexes exhibit Curie-Weiss behavior, except for 2c and 3c, which possess singlet ground states and high spin excited states that are 0.036 and 0.056 eV (290 and 524 cm-1) above the ground state, respectively. Mixed-valent 1a+ and 2a+ are fully detrapped on the Mössbauer time scale (i.e., electron transfer rates ≥107 s-1) above 1.5 K, consistent with a negligible energy barrier to intramolecular electron transfer or complete delocalization. The EPR spectra of 1a+, 2a+, and 1e+ exhibit significantly reduced g-factor ansiotropies and more intense spectral features at ambient temperature compared to [FeCp*2]•+, implying intramolecular electron transfer rates ≥1010 s-1.

AB - The structural characterization and physical properties of [Cp*M(pentalene)M′Cp*]n+ (Cp* = pentamethylcyclopentadiene; M, M′ = Fe, Fe (1a); Co, Co (1b); Ni, Ni (1c); Ru, Ru (1d); Fe, Ru (1e); Fe, Co (1f); n = 0, 1, 2) and [Cp*M(s-indacene)M′Cp*]n+ (s = symmetric) and [Cp*M(as-indacene)M′Cp*]n+ (M, M′ = Fe, Fe (2a, 3a); Co, Co (2b, 3b); Ni, Ni (2c, 3c); n = 0, 1, 2) (as = asymmetric) are reported. The local molecular structure of the organometallic complex does not change significantly with oxidation state; in all cases the Cp*M moieties reside on opposite faces of the fused μ-bridging ring systems, reflecting the dominance of steric effects. These complexes generally exhibit behavior consistent with significant electronic interactions between metal centers, including large electrochemical potential separations between successive one-electron redox events, and for the mixed valent (n = 1+) complexes, intervalent charge transfer absorption bands. The magnetic susceptibility data are consistent with intramolecular ferromagnetic coupling of spins for 1a2+ and 2c2+ and antiferromagnetic coupling of spins for 1c, 1c2+, 1b, 2b, 1c+, 2c+, and 3c+. In general, the paramagnetic complexes exhibit Curie-Weiss behavior, except for 2c and 3c, which possess singlet ground states and high spin excited states that are 0.036 and 0.056 eV (290 and 524 cm-1) above the ground state, respectively. Mixed-valent 1a+ and 2a+ are fully detrapped on the Mössbauer time scale (i.e., electron transfer rates ≥107 s-1) above 1.5 K, consistent with a negligible energy barrier to intramolecular electron transfer or complete delocalization. The EPR spectra of 1a+, 2a+, and 1e+ exhibit significantly reduced g-factor ansiotropies and more intense spectral features at ambient temperature compared to [FeCp*2]•+, implying intramolecular electron transfer rates ≥1010 s-1.

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