Doctoral Dissertations

Date of Award

12-1983

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Major

Chemistry

Major Professor

Clifton Woods

Abstract

The binding tendencies of [(PPh3)2Rh]+ with purine and pyrimidine nucleic bases and nucleosides have been studied utilizing 13C, 1H, and 31P NMR. Several complexes of the type [Rh(PPh3)2(CO)L]PF6, where L = nucleic base or nucleoside, have been prepared and the binding sites of the rhodium(I) cation have been determined. A complex of particular interest is the [Rh(PPh3)2(CO)(Guanosine)]PF6 complex, which is the first recorded instance of coordination of a transition metal to O(6) of guanosine in neutral solution. The influence of the two factors site nucleophilicity and steric interaction upon the observed binding site of the rhodium(I) electrophile is discussed.

Various mixtures of the nucleosides and [(PPh3)2(CO)Rh]+ have been studied in neutral and basic dimethyl-d6-sulfoxide solution. Nucleoside stability orders for the rhodium(I) cation with the nucleosides have been determined. The interaction of [(PPh3)2(CO)Rh]+ with the nucleosides has been shown to result in an increase in the acidity of those protons bound to nitrogens adjacent to the site of complexation. In addition, the disruption of the hydrogen-bonding interactions between the members of a purine-pyrimidine base pair caused by the binding of [(PPh3)2(CO)Rh]+ to one member of the base pair has been studied.

The complementary nature of the 13C, 1H, and 31P NMR techniques is extremely valuable in studying the interactions of nucleic acid derivatives with certain transition metal complexes. The application of these techniques to the characterization of metal-nucleoside complexes, the identification of binding sites, and the study of hydrogen-bonding interactions is discussed.

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