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A comparison of solid state and solution structure for a complex between hydrated lanthanum triflate and [221]cryptandтезисы доклада
- Авторы: Shestakova A.K., Chertkov V.A.
- Сборник: International Symposium and Summer School in Saint Petersburg “Nuclear Magnetic Resonance in Condenced Matter”, 10th Meeting “NMR in Life Sciences”, Saint-Peterburg
- Тезисы
- Год издания: 2013
- Издательство: Izd-vo Sankt-Peterburgskogo universiteta
- Местоположение издательства: Sankt-Peterburg, Russia (Federation)
- Первая страница: 113
- Последняя страница: 113
- Аннотация: Stable complexes of azacrownethers and cryptands with metal ions are known more than two decades. Of special interest are the lanthanide derivatives The application of lanthanides in many fields is closely related to their unusually high co-ordination number and large charge density. Many uses require complexation of the lanthanide with suitable organic ligands, which then allow, for example, introduction of other functions into systems like chemical nucleases. There are not many structural investigations with such systems. Presently we report here the results for a complex between hydrated lanthanum triflate and [221]-cryptand obtained with three independent methods: X-ray diffraction, quantum chemistry calculations and NMR measurements of vicinal spin-spin coupling constants. Complexation leads to dramatic effect on conformation of the ligand. X-Ray diffraction data revealed the structure of innersphere almost C2v–symmetrical complex with [221]cryptand and hydrated lanthanum triflate. We performed a series of ECP quantum chemical calculations (Lanl2dz approach), which support the structure of complexes under study. Experimental vicinal spin-spin coupling constants between protons of neighboring CH2-groups for complexes of lanthanum salts with a series of model macrocyclic ligands (1,10-diaza-18-crown-6 and [2,2,2]-cryptand) in solutions (CDCl3, CD3OD and CD3CN) are in good agreement with the ab’inito calculated ones (PFT DFT with Ub3lyp and 6G/311(d) basis set). The conformation of the biggest loop of the [221]-cryptand is close to that of 1,10 diaza-18-crown-6 in their lanthanum complexes. The complex is of particular interest due to a specific co-ordination sphere with all seven binding sites of the cryptand (all five O and both N-atoms, see fig. 1) and extra three water molecules grouping from the same side of the compound (through the biggest loop of the cryptand). The analysis of the crystal packing revealed, that in crystal molecules are assembled into the two layers by O-H…O bonds (O…O 2.766(6)-2.867(6)Å) formed by the water molecules and СF3SO3 anions. ECP quantum chemical calculations (Lanl2dz approach) support the structure. Experimental vicinal spin-spin coupling constants between protons of neighbouring CH2-groups in solutions (CD3OD and CD3CN) are in good agreement with the ab’inito calculated ones (PFT DFT with Ub3lyp and 6G/311(d) basis set). So, the specific conformation of the ligand in solutions of the complex and in the solid state is entirely the same.
- Добавил в систему: Чертков Вячеслав Алексеевич