Dynamic processes in platinum(II)–adenosine complexes. Preparation, NMR spectroscopic characterisation and crystal structure of isomeric PtII(dien)–adenosine complexes
| Autor: | Raikko Kivekäs, Reijo Sillanpää, Jorma Arpalahti, Karel D. Klika |
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| Rok vydání: | 1998 |
| Předmět: | |
| Zdroj: | Journal of the Chemical Society, Dalton Transactions. :1397-1402 |
| ISSN: | 1364-5447 0300-9246 |
| Popis: | The distribution of aquated PtII(dien) between the adenosine N1 and N7 sites has been found to be affected in aqueous solution not only by lowering the pH, but also by equilibration of the mixture of PtII and nucleoside at high temperature. In the former case PtII predominantly binds to the N7 site (1), whereas the latter procedure significantly increases the amount of the N1-bound complex (2) at the expense of the N7 isomer. Both complexes exhibit two 195Pt resonances at ambient temperature, but 1H and 13C NMR spectra recorded in D2O revealed only signals with expected multiplicities for the adenine moiety. However, in [2H7]dmf the aromatic protons and the dien NH proton resonances were split into two components at –50 °C and the C6–NH2 protons were no longer equivalent in both complexes. This suggests restricted rotation about the platinum–nucleoside bonds and/or conformational changes of the dien ligand. Also rotation of the exocyclic amino group about the C6–N6 bond appears to be restricted at low temperatures. Both complexes were crystallised as perchlorate salts and their crystal structures determined. Based on X-ray data, further disturbance in the platinum(II) co-ordination sphere may be induced by close proximity of the exocyclic amino group of the nucleobase and PtII. |
| Databáze: | OpenAIRE |
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