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Crystal structure of K[PtCl3(caffeine)] and its interactions with important nitrogen-donor ligands |
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| Authors: | Snežana Jovanović Ralph Puchta Olivera Klisurić |
| Institution: | 1. Faculty of Science, Department of Chemistry, University of Kragujevac, Kragujevac, Serbia;2. Department of Chemistry and Pharmacy, Institute for Inorganic Chemistry, University of Erlangen-Nürnberg, Erlangen, Germany;3. Computer Chemistry Center, Department of Chemistry and Pharmacy, University of Erlangen-Nürnberg, Erlangen, Germany;4. Faculty of Sciences, Department of Physics, University of Novi Sad, Novi sad, Serbia |
| Abstract: | The crystal structure of KPtCl3(caffeine)] was determined. The coordination geometry around platinum is square-planar formed by N9 of the caffeine ligand and three Cl? ions. The bond lengths and angles of KPtCl3(caffeine)] were compared with those reported for PtCl3(caffeine)]? and KPtCl3(theobromine)]. At the level of the statistical significance of the data we have compared, no differences in the bond distances and angles for any of these compounds were noticed. Weak interactions between K+ and Cl? are responsible for the formation of 1-D polymeric chains in the crystal structure of the complex. The interactions of KPtCl3(caffeine)] with inosine (Ino) and guanosine-5′-monophosphate (5′-GMP) were studied by 1H NMR spectroscopy at 295 K in D2O in a molar ratio of 1 : 1. The results indicate formation of the reaction product PtCl3(Nu)] (Nu=Ino or 5′-GMP) with the release of caffeine from the coordination sphere of the starting complex. The higher stability of the bond between the Pt(II) ion and Ino or 5′-GMP compared to the stability of the platinum–caffeine bond is confirmed by density functional theory calculations (B3LYP/LANL2DZp) using as models 9-methylhypoxanthine and 9-methylguanine. |
| Keywords: | Crystal structure Pt(II) complex caffeine substitution |