Abstract
Gas-phase photoelectron spectroscopy is used to investigate metal-metal interactions and the mixed-valence positive ion states of biferrocene and bis(μ-fulvalenediyl)diiron. The spectra of phenylferrocene and 1,1′-diphenylferrocene a re used to show that, in comparison to ferrocene, the extension of the ligand π system and the reduced ligand symmetry do not have an appreciable effect on the band profile of the metal-based ionizations. In contrast, the initial ionization bands of both bimetallic molecules, which derive from the metal-based 2E2g ionizations of ferrocene, are spread over a wide energy range, indicating delocalization across the two metal halves of the molecule and formal oxidation states of +21/2 for each metal atom in these cation states. The broadening and splitting of this ionization band for bis(μ-fulvalenediyl)diiron is twice that observed for biferrocene, consistent with a through-bond ligand-mediated mechanism of interaction. Ionizations of the bimetallic molecules that derive from the metal-based 2A1g ionizations of ferrocene occur in a single narrow band, indicating that both through-space and through-ligand interactions are not appreciable for the dz2-based orbitals. The difference between the metal-metal interactions in these positive ion states follows from the different overlap and energy match of the metal orbitals with fulvalendiyl orbitals of the appropriate symmetry. Most important to the metal-metal interaction in the ground ion state are empty fulvalendiyl orbitals with two nodes perpendicular to the C5 planes and gerade and ungerade symmetries with respect to the inversion centers of the molecules. In the gas phase, both species are found to be strongly interacting, delocalized mixed-valence compounds in their ground ion states.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 75-85 |
| Number of pages | 11 |
| Journal | Journal of Organometallic Chemistry |
| Volume | 666 |
| Issue number | 1-2 |
| DOIs | |
| State | Published - Jan 20 2003 |
Fingerprint
Keywords
- Biferrocene
- Fulvalendiyl
- Mixed-valence
- Photoelectron spectroscopy
ASJC Scopus subject areas
- Biochemistry
- Inorganic Chemistry
- Organic Chemistry
- Physical and Theoretical Chemistry
- Materials Chemistry
Cite this
Ligand-mediated metal-metal interactions and localized versus delocalized mixed-valence cation states of biferrocene and bis(μ-fulvalenediyl)diiron characterized in the gas phase by valence photoelectron spectroscopy. / Lichtenberger, Dennis L; Fan, Hua Jun; Gruhn, Nadine E.
In: Journal of Organometallic Chemistry, Vol. 666, No. 1-2, 20.01.2003, p. 75-85.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Ligand-mediated metal-metal interactions and localized versus delocalized mixed-valence cation states of biferrocene and bis(μ-fulvalenediyl)diiron characterized in the gas phase by valence photoelectron spectroscopy
AU - Lichtenberger, Dennis L
AU - Fan, Hua Jun
AU - Gruhn, Nadine E.
PY - 2003/1/20
Y1 - 2003/1/20
N2 - Gas-phase photoelectron spectroscopy is used to investigate metal-metal interactions and the mixed-valence positive ion states of biferrocene and bis(μ-fulvalenediyl)diiron. The spectra of phenylferrocene and 1,1′-diphenylferrocene a re used to show that, in comparison to ferrocene, the extension of the ligand π system and the reduced ligand symmetry do not have an appreciable effect on the band profile of the metal-based ionizations. In contrast, the initial ionization bands of both bimetallic molecules, which derive from the metal-based 2E2g ionizations of ferrocene, are spread over a wide energy range, indicating delocalization across the two metal halves of the molecule and formal oxidation states of +21/2 for each metal atom in these cation states. The broadening and splitting of this ionization band for bis(μ-fulvalenediyl)diiron is twice that observed for biferrocene, consistent with a through-bond ligand-mediated mechanism of interaction. Ionizations of the bimetallic molecules that derive from the metal-based 2A1g ionizations of ferrocene occur in a single narrow band, indicating that both through-space and through-ligand interactions are not appreciable for the dz2-based orbitals. The difference between the metal-metal interactions in these positive ion states follows from the different overlap and energy match of the metal orbitals with fulvalendiyl orbitals of the appropriate symmetry. Most important to the metal-metal interaction in the ground ion state are empty fulvalendiyl orbitals with two nodes perpendicular to the C5 planes and gerade and ungerade symmetries with respect to the inversion centers of the molecules. In the gas phase, both species are found to be strongly interacting, delocalized mixed-valence compounds in their ground ion states.
AB - Gas-phase photoelectron spectroscopy is used to investigate metal-metal interactions and the mixed-valence positive ion states of biferrocene and bis(μ-fulvalenediyl)diiron. The spectra of phenylferrocene and 1,1′-diphenylferrocene a re used to show that, in comparison to ferrocene, the extension of the ligand π system and the reduced ligand symmetry do not have an appreciable effect on the band profile of the metal-based ionizations. In contrast, the initial ionization bands of both bimetallic molecules, which derive from the metal-based 2E2g ionizations of ferrocene, are spread over a wide energy range, indicating delocalization across the two metal halves of the molecule and formal oxidation states of +21/2 for each metal atom in these cation states. The broadening and splitting of this ionization band for bis(μ-fulvalenediyl)diiron is twice that observed for biferrocene, consistent with a through-bond ligand-mediated mechanism of interaction. Ionizations of the bimetallic molecules that derive from the metal-based 2A1g ionizations of ferrocene occur in a single narrow band, indicating that both through-space and through-ligand interactions are not appreciable for the dz2-based orbitals. The difference between the metal-metal interactions in these positive ion states follows from the different overlap and energy match of the metal orbitals with fulvalendiyl orbitals of the appropriate symmetry. Most important to the metal-metal interaction in the ground ion state are empty fulvalendiyl orbitals with two nodes perpendicular to the C5 planes and gerade and ungerade symmetries with respect to the inversion centers of the molecules. In the gas phase, both species are found to be strongly interacting, delocalized mixed-valence compounds in their ground ion states.
KW - Biferrocene
KW - Fulvalendiyl
KW - Mixed-valence
KW - Photoelectron spectroscopy
UR - http://www.scopus.com/inward/record.url?scp=0037454843&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0037454843&partnerID=8YFLogxK
U2 - 10.1016/S0022-328X(02)02035-1
DO - 10.1016/S0022-328X(02)02035-1
M3 - Article
VL - 666
SP - 75
EP - 85
JO - Journal of Organometallic Chemistry
JF - Journal of Organometallic Chemistry
SN - 0022-328X
IS - 1-2
ER -