Show simple item record

dc.contributor.advisorCortés-Figueroa, José E.
dc.contributor.authorIgartúa-Nieves, Elvin
dc.date.accessioned2018-04-09T14:52:17Z
dc.date.available2018-04-09T14:52:17Z
dc.date.issued2012
dc.identifier.urihttps://hdl.handle.net/20.500.11801/345
dc.description.abstractCyclic voltammetry measurements on (η2 -C60)M(CO)5 complexes (M = Cr, Mo, W) and on (C5H10N)3(H)3C60 in dichloromethane showed three C60-centered and reversible reduction/oxidation waves. The E1/2 values of these waves are shifted to positive values relative to the corresponding uncoordinated C60 values. A Jahn -Teller type effect due to C60 spherical surface distortion promoted by C60-metal π-backbonding may explain the observed positive shifts. The complex Ir(CO)(PPh3)2(Cl)(C60) was spectroscopically detected in C60-saturated liquid solutions. Instead, the species Ir(CO)(PPh3)2(Cl)(C60 n- ) (n = 4, 5, 6) were detected electrochemically. Results suggest that electrochemically produced C60 4- and C60 5- displace acetonitrile from Ir(CO)(PPh3)2(Cl)(CH3CN) forming Ir(CO)(PPh3)2(Cl)(C60 4- ) and Ir(CO)(PPh3)2(Cl)(C605- ) followed by one-electron electrochemical reductions forming Ir(CO)(PPh3)2(Cl)(C60 5- ) and Ir(CO)(PPh3)2(Cl)(C606- ), respectively. The Wilkinson’s catalyst when dissolved in benzene or C6D6 under nitrogen or under high vacuum undergoes a series of unreported reactions at room temperature. The species (Ph3P)2Rh(η 2 -(C6H4PPh2))(Ph)(H), Ph-C6D5 and (Ph3P)3Rh(D) were detected in addition to expected formation of the cloro-bridged (Ph3P)4Rh2(μ-Cl)2. The mechanistic description of the reactions based on the behavior of its fluoro-congener, kinetics experiments, and ab initio computational studies, involves reversible intramolecular P-Ph/Rh-Cl exchange on the catalyst producing the non-steady-state intermediate cis-(Ph3P)2Rh(Ph)(Ph2PCl) via metal-phosphido formation. Intermolecular PPh3/PPh2Cl exchange on cis-(Ph3P)2Rh(Ph)(Ph2PCl) produces (Ph3P)3Rh(Ph), that in turn undergoes cyclometalation, solvent oxidative addition and reductive elimination producing Ph-C6D5.
dc.description.abstractMedidas de voltametría cíclica en los complejos de (η 2 -C60)M(CO)5 (M = Cr, Mo, W) y en (C5H10N)3(H)3C60 en diclorometano demostraron tres ondas reversibles de oxidación/reducción centradas en C60. Los valores de E1/2 de éstas ondas se desplazaron a valores positivos relativo a los valores correspondientes a C60 sin coordinar. Un efecto tipo Jahn -Teller debido a la distorsión de la superficie esférica de C60 promovida por retrodonación-π entre C60 y el metal explican los desplazamientos positivos. El complejo Ir(CO)(PPh3)2(Cl)(C60) fue detectado espectroscópicamente en soluciones líquidas saturadas de C60. En lugar, las especies Ir(CO)(PPh3)2(Cl)(C60 n- ) (n = 4, 5, 6) fueron detectadas electroquímicamente. Los resultados sugieren que las especies producidas electroquímicamente C60 4- y C60 5- desplazan a acetonitrilo del complejo Ir(CO)(PPh3)2(Cl)(CH3CN) formando Ir(CO)(PPh3)2(Cl)(C60 4- ) e Ir(CO)(PPh3)2(Cl)(C60 5- ) seguido por reducciones electroquímicas de un electrón formando Ir(CO)(PPh3)2(Cl)(C60 5- ) e Ir(CO)(PPh3)2(Cl)(C60 6- ) una vez son reducidas, respectivamente. El catalítico de Wilkinson al disolverse en benceno o C6D6 bajo nitrógeno ó bajo vacío lleva a cabo una serie de reacciones a temperatura ambiente no reportadas. Las especies (Ph3P)2Rh(η 2 -(C6H4PPh2))(Ph)(H), Ph-C6D5 y (Ph3P)3Rh(D) fueron detectadas además de la esperada formación de complejo con puentes de cloro (Ph3P)4Rh2(μ-Cl)2. La descripción mecanística de las reacciones basadas en el comportamiento del congénero de flúor, experimentos cinéticos, y cómputos ab initio, envuelven intercambio reversible intramolecular de P-Ph/Rh-Cl en el catalizador produciendo el intermediario en estado no-estacionario cis- (Ph3P)2Rh(Ph)(Ph2PCl) vía formación de metal-fosfido. El intercambio PPh3/PPh2Cl en cis-(Ph3P)2Rh(Ph)(Ph2PCl) produce (Ph3P)3Rh(Ph), el cual lleva a cabo ortociclometalación, adición oxidativa del disolvente y eliminación reductiva, la cual produce Ph-C6D5.
dc.description.sponsorshipDonors of The Petroleum Research Fund, administered by the American Chemical Society and the National Science Foundationen_US
dc.language.isoenen_US
dc.subjectIntramolecular Ph/Cl exchangeen_US
dc.subjectWilkinson’s catalysten_US
dc.subjectElectrochemical detectionen_US
dc.subjectC60-Piperidine Adducten_US
dc.subjectLigand substituted metal carbonylsen_US
dc.subject.lcshMetal carbonylsen_US
dc.subject.lcshVoltammetryen_US
dc.subject.lcshFullerenes--Oxidationen_US
dc.subject.lcshReduction (Chemistry)en_US
dc.titleExperimental and Ab initio studies of intramolecular Ph/Cl exchange on Wilkinson’s catalyst and ligand-centered electrochemistry of ligand substituted metal carbonyls (M = Cr, Mo, W, Ir)en_US
dc.typeDissertationen_US
dc.rights.licenseAll rights reserveden_US
dc.rights.holder© 2012 Elvin Igartúa-Nievesen_US
dc.contributor.committeeSantana-Vargas, Alberto
dc.contributor.committeeMeléndez-Martínez, Enrique
dc.contributor.committeeRivera-Pagán, José A.
dc.contributor.committeeCádiz-García, Mayra E.
dc.contributor.representativeMartínez-Iñesta, María M.
thesis.degree.levelPh.D.en_US
thesis.degree.disciplineApplied Chemistryen_US
dc.contributor.collegeCollege of Arts and Sciences - Sciencesen_US
dc.contributor.departmentDepartment of Chemistryen_US
dc.description.graduationSemesterSpringen_US
dc.description.graduationYear2012en_US


Files in this item

Thumbnail

This item appears in the following Collection(s)

  • Theses & Dissertations
    Items included under this collection are theses, dissertations, and project reports submitted as a requirement for completing a degree at UPR-Mayagüez.

Show simple item record

All rights reserved
Except where otherwise noted, this item's license is described as All Rights Reserved