Persistent Link:
http://hdl.handle.net/10150/288844
Title:
The electronic structure of metal acetylides
Author:
Uplinger, Andrew Barrett, 1970-
Issue Date:
1998
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:
Three series of acetylide complexes have been examined by gas phase ultraviolet photoelectron spectroscopy to elucidate the electronic structure and bonding of the acetylide to the metal. The electronic properties of the metal fragments and the acetylides were varied in these systems to understand how the acetylide σ and π systems bond to a metal center. The first series of complexes probes the extent of metal-metal electronic communication through the conjugated, acetylide bridged ruthenium dimer compound [(η⁵-C₅H₅)Ru(CO)₂]₂(μ-C≡C). The broad envelope of overlapping metal ionizations seen in the dimer compound compared to the "monomer" (η⁵-C₅H₅)Ru(CO)₂C≡C-CH₃ revealed extensive metal-metal communication through the acetylide bridge. Also observed was a stabilization of metal ionizations in the ruthenium compounds compared to analogous iron compounds. The second series of acetylide complexes probes the bonding effects of increasing the electron richness at the metal center coupled with increasing electron withdrawing capability on the acetylide. The complexes under examination were of the general formula (η⁵-C₅H₅)ML₂C≡C-R (M = Fe, Ru, L = CO, R = p-C₆H₄-NO₂; M = Ru, L = P(CH₃)₃, R = C₆H₅, p-C₆H₄-NO₂] . Ancillary ligand substitution of trimethylphosphine for carbonyl increased the electron richness at the metal center, and the electron withdrawing capability of the acetylide was increased by para substitution of a nitro group on the phenylacetylide. The filled/filled interaction between the metal-dπ/acetylide-π orbitals dominates the metal-acetylide bonding picture in all of the compounds. Nitro substitution on the phenylacetylide resulted in a substantial inductive charge shift, but minimal π effects were observed. Nitro substituted phenyl derivitives showed similar bonding to the acetylides. The third series of complexes probes acetylide bonding with the M₂R₄P₄ core [M = Mo, P = PMe₃, and R = C≡C-Si(CH₃)₃, C≡C-C(CH₃)₃]. A different bonding picture was revealed in the molybdenum series, with the metal-metal- δ orbital having a filled/filled interaction with the acetylide π orbital, as well as donating electron density into the empty acetylide π* orbital. The effects of silicon substitution on the acetylide is probed by comparing ᵗButylacetylene with trimethylsilylacetylene.
Type:
text; Dissertation-Reproduction (electronic)
Keywords:
Chemistry, Inorganic.
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Graduate College; Chemistry
Degree Grantor:
University of Arizona
Advisor:
Lichtenberger, Dennis L.

Full metadata record

DC FieldValue Language
dc.language.isoen_USen_US
dc.titleThe electronic structure of metal acetylidesen_US
dc.creatorUplinger, Andrew Barrett, 1970-en_US
dc.contributor.authorUplinger, Andrew Barrett, 1970-en_US
dc.date.issued1998en_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.abstractThree series of acetylide complexes have been examined by gas phase ultraviolet photoelectron spectroscopy to elucidate the electronic structure and bonding of the acetylide to the metal. The electronic properties of the metal fragments and the acetylides were varied in these systems to understand how the acetylide σ and π systems bond to a metal center. The first series of complexes probes the extent of metal-metal electronic communication through the conjugated, acetylide bridged ruthenium dimer compound [(η⁵-C₅H₅)Ru(CO)₂]₂(μ-C≡C). The broad envelope of overlapping metal ionizations seen in the dimer compound compared to the "monomer" (η⁵-C₅H₅)Ru(CO)₂C≡C-CH₃ revealed extensive metal-metal communication through the acetylide bridge. Also observed was a stabilization of metal ionizations in the ruthenium compounds compared to analogous iron compounds. The second series of acetylide complexes probes the bonding effects of increasing the electron richness at the metal center coupled with increasing electron withdrawing capability on the acetylide. The complexes under examination were of the general formula (η⁵-C₅H₅)ML₂C≡C-R (M = Fe, Ru, L = CO, R = p-C₆H₄-NO₂; M = Ru, L = P(CH₃)₃, R = C₆H₅, p-C₆H₄-NO₂] . Ancillary ligand substitution of trimethylphosphine for carbonyl increased the electron richness at the metal center, and the electron withdrawing capability of the acetylide was increased by para substitution of a nitro group on the phenylacetylide. The filled/filled interaction between the metal-dπ/acetylide-π orbitals dominates the metal-acetylide bonding picture in all of the compounds. Nitro substitution on the phenylacetylide resulted in a substantial inductive charge shift, but minimal π effects were observed. Nitro substituted phenyl derivitives showed similar bonding to the acetylides. The third series of complexes probes acetylide bonding with the M₂R₄P₄ core [M = Mo, P = PMe₃, and R = C≡C-Si(CH₃)₃, C≡C-C(CH₃)₃]. A different bonding picture was revealed in the molybdenum series, with the metal-metal- δ orbital having a filled/filled interaction with the acetylide π orbital, as well as donating electron density into the empty acetylide π* orbital. The effects of silicon substitution on the acetylide is probed by comparing ᵗButylacetylene with trimethylsilylacetylene.en_US
dc.typetexten_US
dc.typeDissertation-Reproduction (electronic)en_US
dc.subjectChemistry, Inorganic.en_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.disciplineChemistryen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorLichtenberger, Dennis L.en_US
dc.identifier.proquest9832245en_US
dc.identifier.bibrecord.b38551512en_US
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