Exploring the Reactivity of Well-defined Oxide-supported Metal­Alkyl and Alkylidyne Complexes via Surface Organometallic Chemistry

dc.contributor.advisorBasset, Jean-Marie
dc.contributor.authorSaidi, Aya
dc.contributor.committeememberHuang, Kuo-Wei
dc.contributor.committeememberSaikaly, Pascal
dc.contributor.committeememberAstruc, Didier
dc.contributor.departmentPhysical Science and Engineering (PSE) Division
dc.date.accessioned2021-03-02T12:50:51Z
dc.date.available2021-03-02T12:50:51Z
dc.date.issued2021-02
dc.description.abstractSurface Organometallic Chemistry (SOMC) is an excellent approach to erase the gap between homogeneous and heterogeneous catalysis by grafting the molecular organometallic complex on various oxide surfaces, forming well-defined and single-site catalysts. This strategy allows for better characterization as well as the improvement and development of existing and new catalysts. These surface species could promote a wide range of catalytic applications (i.e., metathesis of hydrocarbons, hydrogenolysis of alkanes, and olefin polymerization reactions) depending on the metal center and its coordination sphere. In particular, the grafting of alkylated organometallic complexes of groups 4, 5, and 6 metals on the surface oxide is a thermodynamically favored reaction generally leading to strongly bonded well-defined surface species, which are highly reactive catalysts. This thesis has focused on the preparation, characterization, and catalytic investigation of different supported complexes that contain methyl, alkyl, and alkylidyne ligands. The first part compares the catalytic activity of [(≡Si−O−)W(-CH3)5] and [(≡Si-O-)Mo(≡CtBu)(-CH2tBu)2] surface species experimentally and by DFT calculations in the metathesis reactions of linear classical and functionalized olefins. Both pre-catalysts perform almost equally in the α-olefin metathesis reaction. However, in the functionalized olefin metathesis reaction, W pre-catalyst provides selective metathesis products and performs much better than Mo that gives a range of isomerization products. The second part deals with the synthesis and characterization of [(THF)2Zr(-CH3)4] and its grafting on silica support for the first time. The generated surface species [(≡Si−O−)Zr(CH3)3(THF)2] and [(≡Si−O−)2Zr(CH3)2(THF)2] are used for the conversion of CO2 and propylene oxide to cyclic propylene carbonates achieving a TON of 4227. The third part describes the first synthesis and characterization of the highly unstable homoleptic [Ti(-CH3)4] without any coordinating solvent. This complex was stabilized by grafting on SiO2-700, yielding two fully characterized surface species [(≡Si-O-)TiMe3] and [(≡Si-O-Si≡)(≡Si-O-)TiMe3], which were used in the hydrogenolysis reaction of propane and n-butane, with TONs of 419 and 578, respectively. Finally, the fourth part reports the immobilization and characterization of [TiMe2Cl2], an intermediate in the synthesis of [Ti(-CH3)4], on SiO2-700 resulting in [(≡Si-O-)TiMeCl2] and [(≡Si-O-)TiMe2Cl] surface species. These complexes reacted with a demethylating Lewis acid agent (BARF), forming the corresponding cationic Ti species [(≡Si-O-)TiMeCl]+ and [(≡Si-O-)TiCl2]+. Both neutral and cationic complexes were tested in the ethylene polymerization reaction affording linear HDPE with high molecular weights of 500,367 and 486,612 g/mol.
dc.identifier.citationSaidi, A. (2021). Exploring the Reactivity of Well-defined Oxide-supported Metal­Alkyl and Alkylidyne Complexes via Surface Organometallic Chemistry. KAUST Research Repository. https://doi.org/10.25781/KAUST-36C7J
dc.identifier.doi10.25781/KAUST-36C7J
dc.identifier.urihttp://hdl.handle.net/10754/667808
dc.language.isoen
dc.person.id137444
dc.subjectCatalysis
dc.subjectMethyl ligand
dc.subjectSurface organometallic chemistry
dc.subjectOlefin metathesis
dc.subjectCO2 conversion
dc.subjectHydrogenolysis of alkanes
dc.titleExploring the Reactivity of Well-defined Oxide-supported Metal­Alkyl and Alkylidyne Complexes via Surface Organometallic Chemistry
dc.typeDissertation
display.details.left<span><h5>Type</h5>Dissertation<br><br><h5>Authors</h5><a href="https://repository.kaust.edu.sa/search?query=orcid.id:0000-0003-1959-397X&spc.sf=dc.date.issued&spc.sd=DESC">Saidi, Aya</a> <a href="https://orcid.org/0000-0003-1959-397X" target="_blank"><img src="https://repository.kaust.edu.sa/server/api/core/bitstreams/82a625b4-ed4b-40c8-865a-d6a5225a26a4/content" width="16" height="16"/></a><br><br><h5>Advisors</h5><a href="https://repository.kaust.edu.sa/search?query=orcid.id:0000-0003-3166-8882&spc.sf=dc.date.issued&spc.sd=DESC">Basset, Jean-Marie</a> <a href="https://orcid.org/0000-0003-3166-8882" target="_blank"><img src="https://repository.kaust.edu.sa/server/api/core/bitstreams/82a625b4-ed4b-40c8-865a-d6a5225a26a4/content" width="16" height="16"/></a><br><br><h5>Committee Members</h5><a href="https://repository.kaust.edu.sa/search?query=orcid.id:0000-0003-1900-2658&spc.sf=dc.date.issued&spc.sd=DESC">Huang, Kuo-Wei</a> <a href="https://orcid.org/0000-0003-1900-2658" target="_blank"><img src="https://repository.kaust.edu.sa/server/api/core/bitstreams/82a625b4-ed4b-40c8-865a-d6a5225a26a4/content" width="16" height="16"/></a><br><a href="https://repository.kaust.edu.sa/search?query=orcid.id:0000-0001-7678-3986&spc.sf=dc.date.issued&spc.sd=DESC">Saikaly, Pascal</a> <a href="https://orcid.org/0000-0001-7678-3986" target="_blank"><img src="https://repository.kaust.edu.sa/server/api/core/bitstreams/82a625b4-ed4b-40c8-865a-d6a5225a26a4/content" width="16" height="16"/></a><br>Astruc, Didier<br><br><h5>Program</h5><a href="https://repository.kaust.edu.sa/search?spc.sf=dc.date.issued&spc.sd=DESC&f.program=Chemical Science,equals">Chemical Science</a><br><br><h5>KAUST Department</h5><a href="https://repository.kaust.edu.sa/search?spc.sf=dc.date.issued&spc.sd=DESC&f.department=Physical Science and Engineering (PSE) Division,equals">Physical Science and Engineering (PSE) Division</a><br><br><h5>Date</h5>2021-02</span>
display.details.right<span><h5>Abstract</h5>Surface Organometallic Chemistry (SOMC) is an excellent approach to erase the gap between homogeneous and heterogeneous catalysis by grafting the molecular organometallic complex on various oxide surfaces, forming well-defined and single-site catalysts. This strategy allows for better characterization as well as the improvement and development of existing and new catalysts. These surface species could promote a wide range of catalytic applications (i.e., metathesis of hydrocarbons, hydrogenolysis of alkanes, and olefin polymerization reactions) depending on the metal center and its coordination sphere. In particular, the grafting of alkylated organometallic complexes of groups 4, 5, and 6 metals on the surface oxide is a thermodynamically favored reaction generally leading to strongly bonded well-defined surface species, which are highly reactive catalysts. This thesis has focused on the preparation, characterization, and catalytic investigation of different supported complexes that contain methyl, alkyl, and alkylidyne ligands. The first part compares the catalytic activity of [(≡Si−O−)W(-CH3)5] and [(≡Si-O-)Mo(≡CtBu)(-CH2tBu)2] surface species experimentally and by DFT calculations in the metathesis reactions of linear classical and functionalized olefins. Both pre-catalysts perform almost equally in the α-olefin metathesis reaction. However, in the functionalized olefin metathesis reaction, W pre-catalyst provides selective metathesis products and performs much better than Mo that gives a range of isomerization products. The second part deals with the synthesis and characterization of [(THF)2Zr(-CH3)4] and its grafting on silica support for the first time. The generated surface species [(≡Si−O−)Zr(CH3)3(THF)2] and [(≡Si−O−)2Zr(CH3)2(THF)2] are used for the conversion of CO2 and propylene oxide to cyclic propylene carbonates achieving a TON of 4227. The third part describes the first synthesis and characterization of the highly unstable homoleptic [Ti(-CH3)4] without any coordinating solvent. This complex was stabilized by grafting on SiO2-700, yielding two fully characterized surface species [(≡Si-O-)TiMe3] and [(≡Si-O-Si≡)(≡Si-O-)TiMe3], which were used in the hydrogenolysis reaction of propane and n-butane, with TONs of 419 and 578, respectively. Finally, the fourth part reports the immobilization and characterization of [TiMe2Cl2], an intermediate in the synthesis of [Ti(-CH3)4], on SiO2-700 resulting in [(≡Si-O-)TiMeCl2] and [(≡Si-O-)TiMe2Cl] surface species. These complexes reacted with a demethylating Lewis acid agent (BARF), forming the corresponding cationic Ti species [(≡Si-O-)TiMeCl]+ and [(≡Si-O-)TiCl2]+. Both neutral and cationic complexes were tested in the ethylene polymerization reaction affording linear HDPE with high molecular weights of 500,367 and 486,612 g/mol.<br><br><h5>Citation</h5>Saidi, A. (2021). Exploring the Reactivity of Well-defined Oxide-supported Metal­Alkyl and Alkylidyne Complexes via Surface Organometallic Chemistry. KAUST Research Repository. https://doi.org/10.25781/KAUST-36C7J<br><br><h5>DOI</h5><a href="https://doi.org/10.25781/KAUST-36C7J">10.25781/KAUST-36C7J</a></span>
kaust.request.doiyes
orcid.id0000-0001-7678-3986
orcid.id0000-0003-1900-2658
orcid.id0000-0003-3166-8882
orcid.id0000-0003-1959-397X
refterms.dateFOA2021-03-02T12:50:52Z
thesis.degree.disciplineChemical Science
thesis.degree.grantorKing Abdullah University of Science and Technology
thesis.degree.nameDoctor of Philosophy
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