Silyl substitution effects on metal-pentadienyl bonding: Synthesis, structure, photoelectron spectroscopy, and electronic structure of a high-valent half-open zirconocene

Asha Rajapakshe, Rehan Basta, Atta M. Arif, Richard D. Ernst, Dennis L Lichtenberger

Research output: Contribution to journalArticle

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Abstract

The molecule Cp(3-Me3Si-6,6-dmch)ZrI2 (Cp = η5-cyclopentadienyl; 3-Me3Si-6,6-dmch = η5-3-trimethylsilyl-6,6-dimethylcyclohexadienyl) has been synthesized, and the molecular and electronic structures have been investigated. Photoelectron spectroscopy shows that substitution of a trimethylsilyl group in place of a hydrogen atom on the 6,6-dmch ligand destabilizes all of the ionizations of Cp(3-Me3Si-6,6-dmch)ZrI2 by ca. 0.1-0.2 eV compared to those of Cp(6,6-dmch)ZrI2. Density functional calculations accurately reproduce the experimental structure of the molecule and agree with the observed shift of all ionizations to lower energies. Interestingly, the ionizations are calculated to shift to lower energies without the expected increase in electron density at the metal center. This apparent contradiction is understood from analysis of one-center and two-center charge effects in the molecule. As a consequence of these charge effects, the silyl substitution makes the 3-Me3Si-6,6-dmch ligand a slightly better donor and, surprisingly, also a better acceptor ligand than the 6,6-dmch ligand.

Original languageEnglish (US)
Pages (from-to)2867-2871
Number of pages5
JournalOrganometallics
Volume26
Issue number11
DOIs
StatePublished - May 21 2007

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metal bonding
Photoelectron spectroscopy
Electronic structure
Substitution reactions
Metals
photoelectron spectroscopy
substitutes
electronic structure
Ligands
Ionization
ligands
synthesis
ionization
Molecules
molecules
shift
Molecular structure
Density functional theory
Carrier concentration
Hydrogen

ASJC Scopus subject areas

  • Inorganic Chemistry
  • Organic Chemistry

Cite this

Silyl substitution effects on metal-pentadienyl bonding : Synthesis, structure, photoelectron spectroscopy, and electronic structure of a high-valent half-open zirconocene. / Rajapakshe, Asha; Basta, Rehan; Arif, Atta M.; Ernst, Richard D.; Lichtenberger, Dennis L.

In: Organometallics, Vol. 26, No. 11, 21.05.2007, p. 2867-2871.

Research output: Contribution to journalArticle

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abstract = "The molecule Cp(3-Me3Si-6,6-dmch)ZrI2 (Cp = η5-cyclopentadienyl; 3-Me3Si-6,6-dmch = η5-3-trimethylsilyl-6,6-dimethylcyclohexadienyl) has been synthesized, and the molecular and electronic structures have been investigated. Photoelectron spectroscopy shows that substitution of a trimethylsilyl group in place of a hydrogen atom on the 6,6-dmch ligand destabilizes all of the ionizations of Cp(3-Me3Si-6,6-dmch)ZrI2 by ca. 0.1-0.2 eV compared to those of Cp(6,6-dmch)ZrI2. Density functional calculations accurately reproduce the experimental structure of the molecule and agree with the observed shift of all ionizations to lower energies. Interestingly, the ionizations are calculated to shift to lower energies without the expected increase in electron density at the metal center. This apparent contradiction is understood from analysis of one-center and two-center charge effects in the molecule. As a consequence of these charge effects, the silyl substitution makes the 3-Me3Si-6,6-dmch ligand a slightly better donor and, surprisingly, also a better acceptor ligand than the 6,6-dmch ligand.",
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AU - Ernst, Richard D.

AU - Lichtenberger, Dennis L

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AB - The molecule Cp(3-Me3Si-6,6-dmch)ZrI2 (Cp = η5-cyclopentadienyl; 3-Me3Si-6,6-dmch = η5-3-trimethylsilyl-6,6-dimethylcyclohexadienyl) has been synthesized, and the molecular and electronic structures have been investigated. Photoelectron spectroscopy shows that substitution of a trimethylsilyl group in place of a hydrogen atom on the 6,6-dmch ligand destabilizes all of the ionizations of Cp(3-Me3Si-6,6-dmch)ZrI2 by ca. 0.1-0.2 eV compared to those of Cp(6,6-dmch)ZrI2. Density functional calculations accurately reproduce the experimental structure of the molecule and agree with the observed shift of all ionizations to lower energies. Interestingly, the ionizations are calculated to shift to lower energies without the expected increase in electron density at the metal center. This apparent contradiction is understood from analysis of one-center and two-center charge effects in the molecule. As a consequence of these charge effects, the silyl substitution makes the 3-Me3Si-6,6-dmch ligand a slightly better donor and, surprisingly, also a better acceptor ligand than the 6,6-dmch ligand.

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