کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
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1335346 | 979526 | 2007 | 10 صفحه PDF | دانلود رایگان |
![عکس صفحه اول مقاله: Structure of oxonium hexafluoroniobate and hexafluorotantalate complexes with crown ethers of different dimensionality Structure of oxonium hexafluoroniobate and hexafluorotantalate complexes with crown ethers of different dimensionality](/preview/png/1335346.png)
Two synthetic pathways, the interaction of Nb2O5 or Ta2O5 with an aqueous solution of hydrofluoric acid, HF, in the presence of 18-crown-6 (18C6), 15-crown-5 (15C5), benzo-15-crown-5 (B15C5) or benzo-12-crown-4 (B12C4), and the direct interaction of the corresponding pentafluorides, MF5 (M = Ta, Nb), in the presence of HF with the same crown ethers result in crystalline complexes of the same composition, [18C6 · H3O][NbF6] (1), [18C6 · H3O][TaF6] (2), [15C5 · H5O2][TaF6] (3), [(B15C5)2 · H5O2][(B15C5)2 · H3O][TaF6]2 (4) and [(B12C4)2 · H3O][TaF6] (5). Complexes 1–5 were identified by elemental and X-ray structural analysis. Compounds 1 and 2 are isostructural, with the [H3O]+ oxonium ion embedded in one crown molecule via OH⋯O hydrogen bonds. Complexes 3–5 represent sandwich-like adducts with the [H3O]+ or [H5O2]+ cations encapsulated. A plethora of weak C–H⋯F interactions with NbF6- and TaF6- anions is responsible for the extended supramolecular architectures.
Five novel complexes, [18C6 · H3O][NbF6], [18C6 · H3O][TaF6], [15C5 · H5O2][TaF6], [(B15C5)2 · H5O2][(B15C5)2 · H3O][TaF6]2 and [(B12C4)2 · H3O][TaF6] were synthesized and identified by elemental and X-ray structural analysis.Figure optionsDownload as PowerPoint slide
Journal: Polyhedron - Volume 26, Issue 18, 20 November 2007, Pages 5193–5202