Persistent Link:
http://hdl.handle.net/10150/184742
Title:
Photoelectron spectroscopy of supported metal-metal interactions.
Author:
Copenhaver, Ann Savena.
Issue Date:
1989
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
The bonding in a series of ligand-bridged metal dimer complexes has been characterized by He(I) and He(II) photoelectron spectroscopy and approximate molecular orbital calculations. Bridging ligands such as carbonyl, nitrosyl, methylene and pyrazolyl in the complexes [CpFe(NO)]₂, [Cp*Fe(NO)]₂, [CpRu(NO)]₂, [Cp*Co(CO)]₂, [CpFe(CO)₂]₂, [Cp*Fe(CO)₂]₂, [CpFe(CO)]₂-μCO-μCH₂, [Cp*Fe(CO)]₂-μCO-μCH₂, [CpFe(NO)]₂- μCh₂, [CpRu(NO)]₂-μCH₂, [CpCo(CO)]₂-μCH₂, [CpRh(CO)]₂-μCH₂, [Ir(pyrazolyl)(CO)₂]₂, [Ir(3-methylpyrazolyl)(CO)₂]₂ and [Ir(3,5-dimethylpyrazolyl)(CO)₂]₂ are investigated and their effects upon metal-metal interactions are surveyed. Due to the presence of two d⁷ or d⁸ late metal atoms per molecule, these complexes display many overlapping ionization bands in a narrow valence ionization region. Attention has been given to modelling the photoelectron single ionization with asymmetric and symmetric Gaussians. The overlapping ionizations are successfully represented in terms of the model bandshapes. Thermodynamic relationships between bond dissociation and photoelectron ionization energies are also investigated. With relationships of this type, trends in bond energies may be correlated with ionization energies. Ligand inductive and bonding effects as well as small changes in molecular geometry cause shifts in the metal-based ionizations, which aid chemical understanding and interpretation of the molecular orbital picture. By comparing a series of related metal dimers, the assignment of related ionizations in the photoelectron spectra becomes apparent. Changes in ligand π accepting ability and changes in metal and formal oxidation states are also probed. Addition information is provided by vibrational fine structure in Cp₂Os, [CpFe(NO)]₂, and [Cp*Co(CO)]₂ and spin-orbit splitting in Cp₂Os. The metal-ligand backbonding combinations are found to be the most stable interactions and are responsible for the stability of the metal dimers. Metal-metal interactions are found to be relatively unimportant. Ligands with stronger π accepting abilities allow for more stabilized supported metal dimer complexes.
Type:
text; Dissertation-Reproduction (electronic)
Keywords:
Metal bonding -- Research.; Ligand binding (Biochemistry) -- Research.; Photoelectron spectroscopy.
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Chemistry; Graduate College
Degree Grantor:
University of Arizona
Advisor:
Lichtenberger, Dennis

Full metadata record

DC FieldValue Language
dc.language.isoenen_US
dc.titlePhotoelectron spectroscopy of supported metal-metal interactions.en_US
dc.creatorCopenhaver, Ann Savena.en_US
dc.contributor.authorCopenhaver, Ann Savena.en_US
dc.date.issued1989en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractThe bonding in a series of ligand-bridged metal dimer complexes has been characterized by He(I) and He(II) photoelectron spectroscopy and approximate molecular orbital calculations. Bridging ligands such as carbonyl, nitrosyl, methylene and pyrazolyl in the complexes [CpFe(NO)]₂, [Cp*Fe(NO)]₂, [CpRu(NO)]₂, [Cp*Co(CO)]₂, [CpFe(CO)₂]₂, [Cp*Fe(CO)₂]₂, [CpFe(CO)]₂-μCO-μCH₂, [Cp*Fe(CO)]₂-μCO-μCH₂, [CpFe(NO)]₂- μCh₂, [CpRu(NO)]₂-μCH₂, [CpCo(CO)]₂-μCH₂, [CpRh(CO)]₂-μCH₂, [Ir(pyrazolyl)(CO)₂]₂, [Ir(3-methylpyrazolyl)(CO)₂]₂ and [Ir(3,5-dimethylpyrazolyl)(CO)₂]₂ are investigated and their effects upon metal-metal interactions are surveyed. Due to the presence of two d⁷ or d⁸ late metal atoms per molecule, these complexes display many overlapping ionization bands in a narrow valence ionization region. Attention has been given to modelling the photoelectron single ionization with asymmetric and symmetric Gaussians. The overlapping ionizations are successfully represented in terms of the model bandshapes. Thermodynamic relationships between bond dissociation and photoelectron ionization energies are also investigated. With relationships of this type, trends in bond energies may be correlated with ionization energies. Ligand inductive and bonding effects as well as small changes in molecular geometry cause shifts in the metal-based ionizations, which aid chemical understanding and interpretation of the molecular orbital picture. By comparing a series of related metal dimers, the assignment of related ionizations in the photoelectron spectra becomes apparent. Changes in ligand π accepting ability and changes in metal and formal oxidation states are also probed. Addition information is provided by vibrational fine structure in Cp₂Os, [CpFe(NO)]₂, and [Cp*Co(CO)]₂ and spin-orbit splitting in Cp₂Os. The metal-ligand backbonding combinations are found to be the most stable interactions and are responsible for the stability of the metal dimers. Metal-metal interactions are found to be relatively unimportant. Ligands with stronger π accepting abilities allow for more stabilized supported metal dimer complexes.en_US
dc.typetexten_US
dc.typeDissertation-Reproduction (electronic)en_US
dc.subjectMetal bonding -- Research.en_US
dc.subjectLigand binding (Biochemistry) -- Research.en_US
dc.subjectPhotoelectron spectroscopy.en_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineChemistryen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorLichtenberger, Dennisen_US
dc.contributor.committeememberEnemark, Johnen_US
dc.contributor.committeememberFeltham, Roberten_US
dc.contributor.committeememberWigley, Daviden_US
dc.contributor.committeememberRund, Johnen_US
dc.contributor.committeememberBarfield, Michaelen_US
dc.identifier.proquest9000122en_US
dc.identifier.oclc702670022en_US
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