Synthesis, electrochemical, kinetic and thermodynamic studies of new ruthenocene-containing betadiketonato rhodium(I) complexes with biomedical applications
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Date
2004-05
Authors
Kemp, Kingsley Christian
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Publisher
University of the Free State
Abstract
English: New ruthenocene-containing β -diketones 1-Ruthenocenyl-4,4,4,-trifluorobutan-1,3-dione [Hrctfa, pKa / = 7.31(3)], 1-ruthenocenylbutan-1,3-dione [Hrca, pKa / = 10.22(4)] 1-ruthenocenyl-3- phenylpropan-1,3-dione [(Hbrcm, pKa / = 11.31(4)], 1-ruthenocenyl-3-ferrocenylpropan-1,3-dione [(Hrcfcm; pKa / >13)], and 1,3-diruthenocenylpropane-1,3-dione [(Hdrcm, pKa / >13)], were prepared by the Claisen Condensation of acetylruthenocene and the appropriate ester under the influence of lithium diisopropylamide. The group electronegativity of the ruthenocenyl group (Rc) was determined from the linear relationship between the methyl ester (RCOOMe) infrared carbonyl stretching frequencies and the group electronegativities of known R groups, R = CF3, CH3, C5H5, H, Fc. The [Rh(β -diketonato)(cod)] complexes [Rh(rctfa)(cod)], [Rh(rca)(cod)], [Rh(brcm)(cod)], [Rh(rcfcm)(cod)] and [Rh(drcm)(cod)] were obtained by treating the appropriate β -diketones (Hrctfa, Hrca, Hbrcm, Hrcfcm and Hdrcm) with [Rh2(cod)2Cl2]. Kinetics results for the conversion of the β -diketones (Hrctfa, Hrca, Hbrcm, Hrcfcm and Hdrcm) from the enol to the keto form and vice versa are reported. Kinetics results for the substitution of β -diketonato ligand from the [Rh(β -diketonato)(cod)] complexes ( [Rh(rctfa)(cod)], [Rh(rca)(cod)], [Rh(brcm)(cod)], [Rh(rcfcm)(cod)] and [Rh(drcm)(cod)]) with 1,10-phenantroline in methanol are also presented. Large negative activation entropy values obtained, suggested an associative substitution mechanism. All substitution reactions had no observable mechanistic solvent pathway contribution. Oxidation potentials (Epa vs Ag/Ag + ) for the ruthenium core in the free β -diketones (Hrctfa, Hrca, Hbrcm, Hrcfcm and Hdrcm), as well as in the [Rh(β -diketonato)(cod)] complexes ([Rh(rctfa)(cod)], [Rh(rca)(cod)], [Rh(brcm)(cod)], [Rh(rcfcm)(cod)] and [Rh(drcm)(cod)]) are reported. The peak anodic potentials (Epa vs Ag/Ag + ) for oxidation of the rhodium(I) center were determined.
Afrikaans: Nuwe rutenoseen-bevattende β-diketone, 1-rutenoseniel-4,4,4-trifluorobutaan-1,3-dioon [Hrctfa, pKa / = 7.31(3)], 1-rutenosenielbutaan-1,3-dioon [Hrca, pKa / = 10.22(4)], 1-rutenoseniel-3- fenielpropaan-1,3-dioon [Hbrcm, pKa / = 11.31(3)], 1-rutenoseniel-3-ferrosenielpropaan-1,3-dioon [Hrcfcm, pKa / > 13] en 1,3-dirutenosenielpropaan-1,3-dioon [Hdrcm, pKa / > 13] is berei deur die Claisen kondensasie van asetielrutenoseen en die toepaslike ester onder die invloed van litiumdiisopropielamied. Die groepelektronegatiwiteit van die rutenoseniel groep (Rc) was bepaal vanaf die lineêre verband tussen die metiel ester (RCOOMe) infrarooi karbonielstrekkingsfrekwensie en die groep elektronegatiwiteit van bekende R groepe, R = CF3, CH3, C6H5, H, Fc. Die [Rh(β-diketonato)(cod)]-komplekse [Rh(rctfa)(cod)], [Rh(rca)(cod)], [Rh(brcm)(cod)], [Rh(rcfcm)(cod)] en [Rh(drcm)(cod)] is berei vanaf die reaksie tussen die toepaslike β-diketone (Hrctfa, Hrca, Hbrcm, Hrcfcm en Hdrcm) en [Rh2(cod)2Cl2]. Kinetiese resultate vir die omskakeling van die β-diketone (Hrctfa, Hrca, Hbrcm, Hrcfcm en Hdrcm) van die enol- na die keto-isomeer en omgekeerd word gerapporteer. Kinetiese resultate vir die substitusie van die β-diketonato ligand van die [Rh(β- diketonato)(cod)]-komplekse [Rh(rctfa)(cod)], [Rh(rca)(cod)], [Rh(brcm)(cod)], [Rh(rcfcm)(cod)] en [Rh(drcm)(cod)]) met 1,10-fenantrolien in metanol word ook aangebied. Die groot negatiewe entropie waardes wat verkry is, dui op ‘n assosiatiewe substitusie meganisme. Alle substitusie reaksies vind met die afwesigheid van ‘n oplosmiddelroete plaas. Oksidasiepotensiale (Ep waardes vs. Ag/Ag+ ) van die rutenium kern in die vry β-diketone (Hrctfa, Hrca, Hbrcm, Hrcfcm en Hdrcm), en in die [Rh(β-diketanato)(cod)] komplekse, [Rh(rctfa)(cod)], [Rh(rca)(cod)], [Rh(brcm)(cod)], [Rh(rcfcm)(cod)] en [Rh(drcm)(cod)]) is bepaal. Die piek oksidasiepotensiale (Ep waardes vs. Ag/Ag+ ) vir die oksidasie van die rodium(I) kern is bepaal.
Afrikaans: Nuwe rutenoseen-bevattende β-diketone, 1-rutenoseniel-4,4,4-trifluorobutaan-1,3-dioon [Hrctfa, pKa / = 7.31(3)], 1-rutenosenielbutaan-1,3-dioon [Hrca, pKa / = 10.22(4)], 1-rutenoseniel-3- fenielpropaan-1,3-dioon [Hbrcm, pKa / = 11.31(3)], 1-rutenoseniel-3-ferrosenielpropaan-1,3-dioon [Hrcfcm, pKa / > 13] en 1,3-dirutenosenielpropaan-1,3-dioon [Hdrcm, pKa / > 13] is berei deur die Claisen kondensasie van asetielrutenoseen en die toepaslike ester onder die invloed van litiumdiisopropielamied. Die groepelektronegatiwiteit van die rutenoseniel groep (Rc) was bepaal vanaf die lineêre verband tussen die metiel ester (RCOOMe) infrarooi karbonielstrekkingsfrekwensie en die groep elektronegatiwiteit van bekende R groepe, R = CF3, CH3, C6H5, H, Fc. Die [Rh(β-diketonato)(cod)]-komplekse [Rh(rctfa)(cod)], [Rh(rca)(cod)], [Rh(brcm)(cod)], [Rh(rcfcm)(cod)] en [Rh(drcm)(cod)] is berei vanaf die reaksie tussen die toepaslike β-diketone (Hrctfa, Hrca, Hbrcm, Hrcfcm en Hdrcm) en [Rh2(cod)2Cl2]. Kinetiese resultate vir die omskakeling van die β-diketone (Hrctfa, Hrca, Hbrcm, Hrcfcm en Hdrcm) van die enol- na die keto-isomeer en omgekeerd word gerapporteer. Kinetiese resultate vir die substitusie van die β-diketonato ligand van die [Rh(β- diketonato)(cod)]-komplekse [Rh(rctfa)(cod)], [Rh(rca)(cod)], [Rh(brcm)(cod)], [Rh(rcfcm)(cod)] en [Rh(drcm)(cod)]) met 1,10-fenantrolien in metanol word ook aangebied. Die groot negatiewe entropie waardes wat verkry is, dui op ‘n assosiatiewe substitusie meganisme. Alle substitusie reaksies vind met die afwesigheid van ‘n oplosmiddelroete plaas. Oksidasiepotensiale (Ep waardes vs. Ag/Ag+ ) van die rutenium kern in die vry β-diketone (Hrctfa, Hrca, Hbrcm, Hrcfcm en Hdrcm), en in die [Rh(β-diketanato)(cod)] komplekse, [Rh(rctfa)(cod)], [Rh(rca)(cod)], [Rh(brcm)(cod)], [Rh(rcfcm)(cod)] en [Rh(drcm)(cod)]) is bepaal. Die piek oksidasiepotensiale (Ep waardes vs. Ag/Ag+ ) vir die oksidasie van die rodium(I) kern is bepaal.
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Keywords
Substitution kinetics, Isomerization kinetics, Rhodium, Dissertation (M.Sc. (Chemistry))--University of the Free State, 2004, Rhodium compounds -- Synthesis, Organic compounds -- Synthesis