An Exploration of the Inorganic, Organometallic, and Catalytic Potential of [Re6(μ3-Se)8]2+ Core-Containing Cluster Derivatives: Synthesis, Characterization, Computational Analysis, and Applications

Persistent Link:
http://hdl.handle.net/10150/193730
Title:
An Exploration of the Inorganic, Organometallic, and Catalytic Potential of [Re6(μ3-Se)8]2+ Core-Containing Cluster Derivatives: Synthesis, Characterization, Computational Analysis, and Applications
Author:
Kueffer, Peter James
Issue Date:
2008
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:
Investigations of small molecules activated through ligation to the Lewis acidic [Re6(μ3-Se)8]2+ cluster core are detailed herein for the purpose of the development of unrealized organometallic and catalytic applications. An introduction is provided including the background needed to comprehend access to the solution chemistry, the general properties, and the current state of development of the [Re6(μ3-Se)8]2+ cluster core. Activation of nitriles is examined, specifically focusing on the site-differentiated cluster acetonitrile solvates of the general form [Re6(μ3-Se)8(PEt3)6-n(MeCN)n](SbF6)2 (n = 1,2) and the hexaacetonitrile solvate [Re6(μ3-Se)8(MeCN)6](SbF6)2. Coordination of acetonitrile to the cluster core yields susceptibility of the nitrile carbon to nucleophilic attack; thus, the formation of the alcohol adducts of these molecules, the stereochemical features, and the reactivity of the resulting imino ester complexes is established. Bifurcated hydrogen bonding between two selenium atoms of the core and the hydrogen atom of an approaching alcohol is proposed to explain the stereoselectivity. Furthermore, the synthesis, characterization, computational analysis, and reactivity of the first organometallic compounds of the [Re6(μ3-Se)8]2+ cluster core, that of the cluster carbonyls [Re6(μ3-Se)8(PEt3)6-n(CO)n](SbF6)2 (n = 1,2), are presented. Spectroscopic, electrochemical, structural, and computational studies verify that backbonding between the [Re6(μ3-Se)8]2+ cluster core and CO exists, that electronic distinction is inherent between cis and trans sites (despite overall delocalization), and that the Se atoms actively contribute to the Re bonding capabilities. Substantiation of the high air, water, thermal, and UV light stability of the carbonyl complexes led to derivatives of the carbonyl compounds, that of the oxidized cluster complex [Re6(μ3-Se)8(PEt3)5Cl](SbF6)2 and the known fused-cluster dimer [Re12Se16(PEt3)10](SbF6)4, demonstrating the reactivity of the cluster carbonyls. Electrophilicty of coordinated CO is exemplified through the synthesis of an acyl complex {Re6(μ3-Se)8(PEt3)5[C(O)(CH3)]}I, an unexpectedly stable product in the pursuit a cluster carbene. Initial investigations of this complex suggest thorough transference of the acyl negative charge to the cluster core prohibiting successive electrophilic addition. The putative acetone solvate and its reactivity to alcohols is briefly examined with aspects that merit further research, including full characterization of the catalytic cycle to liberate free imino esters, exploitation of the proposed hydrogen bonding to generate a carbene compound, and hydrogen storage/activation.
Type:
text; Electronic Dissertation
Keywords:
Chemistry
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Chemistry; Graduate College
Degree Grantor:
University of Arizona
Advisor:
Zheng, Zhiping
Committee Chair:
Zheng, Zhiping

Full metadata record

DC FieldValue Language
dc.language.isoenen_US
dc.titleAn Exploration of the Inorganic, Organometallic, and Catalytic Potential of [Re6(μ3-Se)8]2+ Core-Containing Cluster Derivatives: Synthesis, Characterization, Computational Analysis, and Applicationsen_US
dc.creatorKueffer, Peter Jamesen_US
dc.contributor.authorKueffer, Peter Jamesen_US
dc.date.issued2008en_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.abstractInvestigations of small molecules activated through ligation to the Lewis acidic [Re6(μ3-Se)8]2+ cluster core are detailed herein for the purpose of the development of unrealized organometallic and catalytic applications. An introduction is provided including the background needed to comprehend access to the solution chemistry, the general properties, and the current state of development of the [Re6(μ3-Se)8]2+ cluster core. Activation of nitriles is examined, specifically focusing on the site-differentiated cluster acetonitrile solvates of the general form [Re6(μ3-Se)8(PEt3)6-n(MeCN)n](SbF6)2 (n = 1,2) and the hexaacetonitrile solvate [Re6(μ3-Se)8(MeCN)6](SbF6)2. Coordination of acetonitrile to the cluster core yields susceptibility of the nitrile carbon to nucleophilic attack; thus, the formation of the alcohol adducts of these molecules, the stereochemical features, and the reactivity of the resulting imino ester complexes is established. Bifurcated hydrogen bonding between two selenium atoms of the core and the hydrogen atom of an approaching alcohol is proposed to explain the stereoselectivity. Furthermore, the synthesis, characterization, computational analysis, and reactivity of the first organometallic compounds of the [Re6(μ3-Se)8]2+ cluster core, that of the cluster carbonyls [Re6(μ3-Se)8(PEt3)6-n(CO)n](SbF6)2 (n = 1,2), are presented. Spectroscopic, electrochemical, structural, and computational studies verify that backbonding between the [Re6(μ3-Se)8]2+ cluster core and CO exists, that electronic distinction is inherent between cis and trans sites (despite overall delocalization), and that the Se atoms actively contribute to the Re bonding capabilities. Substantiation of the high air, water, thermal, and UV light stability of the carbonyl complexes led to derivatives of the carbonyl compounds, that of the oxidized cluster complex [Re6(μ3-Se)8(PEt3)5Cl](SbF6)2 and the known fused-cluster dimer [Re12Se16(PEt3)10](SbF6)4, demonstrating the reactivity of the cluster carbonyls. Electrophilicty of coordinated CO is exemplified through the synthesis of an acyl complex {Re6(μ3-Se)8(PEt3)5[C(O)(CH3)]}I, an unexpectedly stable product in the pursuit a cluster carbene. Initial investigations of this complex suggest thorough transference of the acyl negative charge to the cluster core prohibiting successive electrophilic addition. The putative acetone solvate and its reactivity to alcohols is briefly examined with aspects that merit further research, including full characterization of the catalytic cycle to liberate free imino esters, exploitation of the proposed hydrogen bonding to generate a carbene compound, and hydrogen storage/activation.en_US
dc.typetexten_US
dc.typeElectronic Dissertationen_US
dc.subjectChemistryen_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.advisorZheng, Zhipingen_US
dc.contributor.chairZheng, Zhipingen_US
dc.contributor.committeememberEnemark, Johnen_US
dc.contributor.committeememberLichtenberger, Dennisen_US
dc.contributor.committeememberWysocki, Vickien_US
dc.contributor.committeememberArmstrong, Neal R.en_US
dc.identifier.proquest2687en_US
dc.identifier.oclc659749692en_US
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