Metal-stabilized rare tautomers of nucleobases |
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| Authors: | F. Pichierri D. Holthenrich E. Zangrando B. Lippert L. Randaccio |
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| Affiliation: | (1) Department of Chemistry, University of Trieste, Via Giogieri 1, I-34127 Trieste, Italy, IT;(2) Department of Chemistry, University of Dortmund, Otto-Hahn-Strasse 6, D-44221 Dortmund, Germany, DE |
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| Abstract: | A PtII complex containing N4 bound neutral 1-methylcytosine (1-MeC), trans–[Pt(NH3)2(1-MeC-N4)2](ClO4)2 (5), has been prepared and characterized by X-ray analysis. The complex contains the rare iminooxo tautomer form of the cytosine nucleobase. PtII binding is through the exocyclic N4 position of the nucleobases, with Pt and the N3 positions in a syn orientation. As a consequence, the proton at N3 is pointing toward the heavy metal, thereby allowing an agostic Pt···HN interaction. Formation of 5 is achieved via oxidation of the linkage isomer trans–[Pt(NH3)2(1-MeC-N3)2]2+ (1) to a PtIV species (2), followed by metal migration to N4, and subsequent reduction to PtII. This process is a text-book example for a redox-assisted metal migration at a heterocyclic ligand. The existence of various rotamers of 5 in aqueous solution is evident from 1H NMR spectroscopy. The possible role of these rotamers of the metalated rare tautomer, and in particular of those having Pt and the N3 position in an anti arrangement, with regard to base mispairing is discussed. Received: 27 February 1996 / Accepted: 10 June 1996 |
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| Keywords: | Cytosine Rare iminooxo tautomer Syn and anti arrangement |
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