{"id":{"repo_id":"tdl","oai_identifier":"oai:tdl-ir.tdl.org:1969.1/ETD-TAMU-2009-05-283"},"canonical_url":"https://search.dev.ndltd.org/etd/tdl/oai:tdl-ir.tdl.org:1969.1/ETD-TAMU-2009-05-283","repository":{"repo_id":"tdl","name":"Texas Digital Library","base_url":"https://tdl-ir.tdl.org/server/oai/request"},"display":{"title":"Theoretical Studies of Structures and Mechanisms in Organometallic and Bioinorganic Chemistry: Heck Reaction with Palladium Phosphines, Active Sites of Superoxide Reductase and Cytochrome P450 Monooxygenase, and Tetrairon Hexathiolate Hydrogenase Model","abstract":"The electronic structures and reaction mechanisms of transition-metal complexes can be calculated accurately by density functional theory (DFT) in cooperation with the continuum solvation model. The palladium catalyzed Heck reaction, iron-model complexes for cytochrome P450 and superoxide reductase (SOR), and tetrairon hexathiolate hydrogenase model were investigated. The DFT calculations on the catalytic Heck reaction (between phenyl-bromide and ethylene to form the styrene product), catalyzed by palladium diphosphine indicate a four-step mechanism: oxidative addition of C6H5Br, migratory insertion of C6H5 to C2H4, b-hydride transfer/olefin elimination of styrene product, and catalyst regeneration by removal of HBr. For the oxidative addition, the rate-determining step, the reaction through monophosphinopalladium complex is more favorable than that through either the diphosphinopalladium or ethylene-bound monophosphinopalladium. In further study, for a steric phosphine, PtBu3, the oxidative-addition barrier is lower on monopalladium monophosphine than dipalladium diphosphine whereas for a small phosphine, PMe3, the oxidative addition proceeds more easily via dipalladium diphosphine. Of the phosphine-free palladium complexes examined: free-Pd, PdBr-, and Pd(h2-C2H4), the olefin-coordinated intermediate has the lowest barrier for the oxidativeaddition. P450 and SOR have the same first-coordination-sphere, Fe[N4S], at their active sites but proceed through different reaction paths. The different ground spin states of the intermediate FeIII(OOH)(SCH3)(L) model {L = porphyrin for P450 and four imidazoles for SOR} produce geometric and electronic structures that assist i) the protonation on distal oxygen for P450, which leads to O-O bond cleavage and formation of (FeIV=O)(SCH3)(L) H2O, and ii) the protonation on proximal oxygen for SOR, which leads to (FeIII-HOOH)(SCH3)(L) formation before the Fe-O bond cleavage and H2O2 production. The hydrogen bonding from explicit waters also stabilizes FeIII-HOOH over FeIV=O H2O products in SOR. The electrochemical hydrogen production by Fe4[MeC(CH2S)3]2(CO)8 (1) with 2,6-dimethylpyridinium (LutH ) were studied by the DFT calculations of proton-transfer free energies relative to LutH and reduction potentials (vs. Fc/Fc ) of possible intermediates. In hydrogen production by 1, the second, more highly reductive, applied potential (-1.58 V) has the advantage over the first applied potential (-1.22 V) in that the more highly reduced intermediates can more easily add protons to produce H2.","abstract_html":"The electronic structures and reaction mechanisms of transition-metal complexes can be calculated accurately by density functional theory (DFT) in cooperation with the continuum solvation model. The palladium catalyzed Heck reaction, iron-model complexes for cytochrome P450 and superoxide reductase (SOR), and tetrairon hexathiolate hydrogenase model were investigated. The DFT calculations on the catalytic Heck reaction (between phenyl-bromide and ethylene to form the styrene product), catalyzed by palladium diphosphine indicate a four-step mechanism: oxidative addition of C6H5Br, migratory insertion of C6H5 to C2H4, b-hydride transfer/olefin elimination of styrene product, and catalyst regeneration by removal of HBr. For the oxidative addition, the rate-determining step, the reaction through monophosphinopalladium complex is more favorable than that through either the diphosphinopalladium or ethylene-bound monophosphinopalladium. In further study, for a steric phosphine, PtBu3, the oxidative-addition barrier is lower on monopalladium monophosphine than dipalladium diphosphine whereas for a small phosphine, PMe3, the oxidative addition proceeds more easily via dipalladium diphosphine. Of the phosphine-free palladium complexes examined: free-Pd, PdBr-, and Pd(h2-C2H4), the olefin-coordinated intermediate has the lowest barrier for the oxidativeaddition. P450 and SOR have the same first-coordination-sphere, Fe[N4S], at their active sites but proceed through different reaction paths. The different ground spin states of the intermediate FeIII(OOH)(SCH3)(L) model {L = porphyrin for P450 and four imidazoles for SOR} produce geometric and electronic structures that assist i) the protonation on distal oxygen for P450, which leads to O-O bond cleavage and formation of (FeIV=O)(SCH3)(L) H2O, and ii) the protonation on proximal oxygen for SOR, which leads to (FeIII-HOOH)(SCH3)(L) formation before the Fe-O bond cleavage and H2O2 production. The hydrogen bonding from explicit waters also stabilizes FeIII-HOOH over FeIV=O H2O products in SOR. The electrochemical hydrogen production by Fe4[MeC(CH2S)3]2(CO)8 (1) with 2,6-dimethylpyridinium (LutH ) were studied by the DFT calculations of proton-transfer free energies relative to LutH and reduction potentials (vs. Fc/Fc ) of possible intermediates. In hydrogen production by 1, the second, more highly reductive, applied potential (-1.58 V) has the advantage over the first applied potential (-1.22 V) in that the more highly reduced intermediates can more easily add protons to produce H2.","abstract_has_math":false,"creators":["Surawatanawong, Panida"],"institution":null,"degree_name":null,"degree_level":null,"degree_discipline":null,"degree_department":null,"school":null,"contributors":["Hall, Michael B."],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2010,"date_issued":"2010-07-14","date_published":"2010-07-14","updated_at":"2026-08-21T22:21:56Z","subjects":["Palladium","Heck reaction","Superoxide Reductase","Cytochrome P450","Hydrogenase","Density Functional Theory"],"languages":["eng"],"rights":[],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"http://hdl.handle.net/1969.1/ETD-TAMU-2009-05-283","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"source_record":{"url":"https://tdl-ir.tdl.org/server/oai/request?verb=GetRecord&metadataPrefix=dim&identifier=oai%3Atdl-ir.tdl.org%3A1969.1%2FETD-TAMU-2009-05-283","prefix":"dim"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Hall, Michael B."]},{"key":"dc:creator","label":"Author","values":["Surawatanawong, Panida"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2010-07-15T00:11:10Z","2010-07-23T21:42:53Z","2017-04-07T19:57:02Z"]},{"key":"dc:date.available","label":"Dc Date Available","values":["2010-07-15T00:11:10Z","2010-07-23T21:42:53Z","2017-04-07T19:57:02Z"]},{"key":"dc:date.issued","label":"Date","values":["2010-07-14"]},{"key":"dc:type","label":"Dc Type","values":["Book","Thesis"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Palladium","Heck reaction","Superoxide Reductase","Cytochrome P450","Hydrogenase","Density Functional Theory"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language.iso","label":"Language (ISO)","values":["eng"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.uri","label":"Identifier URI","values":["http://hdl.handle.net/1969.1/ETD-TAMU-2009-05-283"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["The electronic structures and reaction mechanisms of transition-metal complexes can be calculated accurately by density functional theory (DFT) in cooperation with the continuum solvation model. The palladium catalyzed Heck reaction, iron-model complexes for cytochrome P450 and superoxide reductase (SOR), and tetrairon hexathiolate hydrogenase model were investigated. The DFT calculations on the catalytic Heck reaction (between phenyl-bromide and ethylene to form the styrene product), catalyzed by palladium diphosphine indicate a four-step mechanism: oxidative addition of C6H5Br, migratory insertion of C6H5 to C2H4, b-hydride transfer/olefin elimination of styrene product, and catalyst regeneration by removal of HBr. For the oxidative addition, the rate-determining step, the reaction through monophosphinopalladium complex is more favorable than that through either the diphosphinopalladium or ethylene-bound monophosphinopalladium. In further study, for a steric phosphine, PtBu3, the oxidative-addition barrier is lower on monopalladium monophosphine than dipalladium diphosphine whereas for a small phosphine, PMe3, the oxidative addition proceeds more easily via dipalladium diphosphine. Of the phosphine-free palladium complexes examined: free-Pd, PdBr-, and Pd(h2-C2H4), the olefin-coordinated intermediate has the lowest barrier for the oxidativeaddition. P450 and SOR have the same first-coordination-sphere, Fe[N4S], at their active sites but proceed through different reaction paths. The different ground spin states of the intermediate FeIII(OOH)(SCH3)(L) model {L = porphyrin for P450 and four imidazoles for SOR} produce geometric and electronic structures that assist i) the protonation on distal oxygen for P450, which leads to O-O bond cleavage and formation of (FeIV=O)(SCH3)(L) H2O, and ii) the protonation on proximal oxygen for SOR, which leads to (FeIII-HOOH)(SCH3)(L) formation before the Fe-O bond cleavage and H2O2 production. The hydrogen bonding from explicit waters also stabilizes FeIII-HOOH over FeIV=O H2O products in SOR. The electrochemical hydrogen production by Fe4[MeC(CH2S)3]2(CO)8 (1) with 2,6-dimethylpyridinium (LutH ) were studied by the DFT calculations of proton-transfer free energies relative to LutH and reduction potentials (vs. Fc/Fc ) of possible intermediates. In hydrogen production by 1, the second, more highly reductive, applied potential (-1.58 V) has the advantage over the first applied potential (-1.22 V) in that the more highly reduced intermediates can more easily add protons to produce H2."]},{"key":"dc:title","label":"Title","values":["Theoretical Studies of Structures and Mechanisms in Organometallic and Bioinorganic Chemistry: Heck Reaction with Palladium Phosphines, Active Sites of Superoxide Reductase and Cytochrome P450 Monooxygenase, and Tetrairon Hexathiolate Hydrogenase Model"]}]}],"canonical_facts":{"dc:contributor":["Hall, Michael B."],"dc:creator":["Surawatanawong, Panida"],"dc:date.accessioned":["2010-07-15T00:11:10Z","2010-07-23T21:42:53Z","2017-04-07T19:57:02Z"],"dc:date.available":["2010-07-15T00:11:10Z","2010-07-23T21:42:53Z","2017-04-07T19:57:02Z"],"dc:date.issued":["2010-07-14"],"dc:description.abstract":["The electronic structures and reaction mechanisms of transition-metal complexes can be calculated accurately by density functional theory (DFT) in cooperation with the continuum solvation model. The palladium catalyzed Heck reaction, iron-model complexes for cytochrome P450 and superoxide reductase (SOR), and tetrairon hexathiolate hydrogenase model were investigated. The DFT calculations on the catalytic Heck reaction (between phenyl-bromide and ethylene to form the styrene product), catalyzed by palladium diphosphine indicate a four-step mechanism: oxidative addition of C6H5Br, migratory insertion of C6H5 to C2H4, b-hydride transfer/olefin elimination of styrene product, and catalyst regeneration by removal of HBr. For the oxidative addition, the rate-determining step, the reaction through monophosphinopalladium complex is more favorable than that through either the diphosphinopalladium or ethylene-bound monophosphinopalladium. In further study, for a steric phosphine, PtBu3, the oxidative-addition barrier is lower on monopalladium monophosphine than dipalladium diphosphine whereas for a small phosphine, PMe3, the oxidative addition proceeds more easily via dipalladium diphosphine. Of the phosphine-free palladium complexes examined: free-Pd, PdBr-, and Pd(h2-C2H4), the olefin-coordinated intermediate has the lowest barrier for the oxidativeaddition. P450 and SOR have the same first-coordination-sphere, Fe[N4S], at their active sites but proceed through different reaction paths. The different ground spin states of the intermediate FeIII(OOH)(SCH3)(L) model {L = porphyrin for P450 and four imidazoles for SOR} produce geometric and electronic structures that assist i) the protonation on distal oxygen for P450, which leads to O-O bond cleavage and formation of (FeIV=O)(SCH3)(L) H2O, and ii) the protonation on proximal oxygen for SOR, which leads to (FeIII-HOOH)(SCH3)(L) formation before the Fe-O bond cleavage and H2O2 production. The hydrogen bonding from explicit waters also stabilizes FeIII-HOOH over FeIV=O H2O products in SOR. The electrochemical hydrogen production by Fe4[MeC(CH2S)3]2(CO)8 (1) with 2,6-dimethylpyridinium (LutH ) were studied by the DFT calculations of proton-transfer free energies relative to LutH and reduction potentials (vs. Fc/Fc ) of possible intermediates. In hydrogen production by 1, the second, more highly reductive, applied potential (-1.58 V) has the advantage over the first applied potential (-1.22 V) in that the more highly reduced intermediates can more easily add protons to produce H2."],"dc:identifier.uri":["http://hdl.handle.net/1969.1/ETD-TAMU-2009-05-283"],"dc:language.iso":["eng"],"dc:subject":["Palladium","Heck reaction","Superoxide Reductase","Cytochrome P450","Hydrogenase","Density Functional Theory"],"dc:title":["Theoretical Studies of Structures and Mechanisms in Organometallic and Bioinorganic Chemistry: Heck Reaction with Palladium Phosphines, Active Sites of Superoxide Reductase and Cytochrome P450 Monooxygenase, and Tetrairon Hexathiolate Hydrogenase Model"],"dc:type":["Book","Thesis"]},"updated_at":"2026-08-21T22:21:56Z"}