A detailed kinetic and mechanistic investigation into the rate of chloride substitution from chloro terpyridine platinum (II) and analogous complexes by a series of azole nucleophiles.

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dc.contributor.advisor Reddy, D.
dc.contributor.advisor Jaganyi, Deogratius.
dc.creator Gillham, Kate J.
dc.date.accessioned 2010-08-15T17:48:28Z
dc.date.available 2010-08-15T17:48:28Z
dc.date.created 2010
dc.date.issued 2010
dc.identifier.uri http://hdl.handle.net/10413/90
dc.description Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2010. en_US
dc.description.abstract The substitution kinetics of the complexes: [Pt(terpy)Cl]Cl?2H2O (PtL1), [Pt(tBu3terpy)Cl]ClO4 (PtL2), [Pt{4?-(2???-CH3-Ph)terpy}Cl]BF4 (PtL3), [Pt{4?-(2???-CF3-Ph)terpy}Cl]CF3SO4 (PtL4), [Pt{4?-(2???-CF3-Ph)-6-Ph-bipy}Cl] (PtL5) and [Pt{4?-(2???-CH3-Ph)-6-2??-pyrazinyl-2,2?-bipy}Cl]CF3SO3 (PtL6) with the nucleophiles: imidazole (Im), 1-methylimdazole (MIm), 1,2-dimethylimidazole (DIm), pyrazole (pyz) and 1,2,4-triazole (Trz) were investigated in a methanolic solution of constant ionic strength. Substitution of the chloride ligand from the metal complexes by the nucleophiles was investigated as a function of nucleophile concentration and temperature under pseudo first-order condition using UV/Visible and stopped-flow spectrophotometric techniques. The results obtained indicate that by either changing the substituents on the terpy backbone or by slight modification of the chelate itself leads to changes in the ?-acceptor ability of the chelate. This in turn controls the electrophilicity of the metal centre and hence its reactivity. In the case of PtL3 and PtL4, the ortho substituent on the phenyl ring at the 4?-position on the terpy backbone is either electron-donating or electron-withdrawing respectively. For an electron-donating group (CH3, PtL3) the reactivity of the metal centre is decreased whilst an electron-withdrawing group (CF3, PtL4) lead to a moderate increase in reactivity. Electron-donating groups attached directly to the terpy moiety (tBu3, PtL2) also leads to a decrease in the rate of chloride substitution. Placing a strong ?-donor cis to the leaving group (PtL5) greatly decreases the reactivity of a complex while the addition of a good ?-acceptor group (PtL6) significantly enhances the reactivity. The results obtained for PtL5 and PtL6 indicate that the group present in the cis position activates the metal centre in a different manner than when in the trans position. The experimental results obtained were supported by DFT calculations at the B3LYP/LACVP+** level of theory, with the NBO charges showing a less electrophilic Pt(II) centre when a strong ?-donor cis to the leaving group was present such as in PtL5 and a more electrophilic centre for complexes with good ?-acceptor groups such as with PtL6. Surprisingly, the results indicate that in the case of PtL5, when the metal centre was less electrophilic it also appears to be less selective. en_US
dc.language.iso en en_US
dc.subject Platinum compounds.
dc.subject Antineoplastic agents.
dc.subject Theses--Chemistry.
dc.title A detailed kinetic and mechanistic investigation into the rate of chloride substitution from chloro terpyridine platinum (II) and analogous complexes by a series of azole nucleophiles. en_US
dc.type Thesis en_US
dc.description.notes Accompanying CD-ROM, consisting of Appendix F, housed at Cecil Renaud Library Issue Desk.

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