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 language | English (US) |
|---|---|
| Pages (from-to) | 6182-6192 |
| Number of pages | 11 |
| Journal | Journal of the American Chemical Society |
| Volume | 117 |
| Issue number | 23 |
| State | Published - Jun 14 1995 |
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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 journal › Article
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TY - JOUR
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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M3 - Article
AN - SCOPUS:0346622799
VL - 117
SP - 6182
EP - 6192
JO - Journal of the American Chemical Society
JF - Journal of the American Chemical Society
SN - 0002-7863
IS - 23
ER -