Crystal structures of dioxonium hexafluorotantalate and dioxonium hexafluoroniobate complexes with tetrabenzo-30-crown-1
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TURE OF ORGANIC COMPOUNDS
Crystal Structures of Dioxonium Hexafluorotantalate and Dioxonium Hexafluoroniobate Complexes with Tetrabenzo-30-Crown-10 N. G. Furmanovaa, M. Kh. Rabadanova, T. S. Chernayaa, M. S. Fonarib, Yu. A. Simonovb, É. V. Ganinc, V. O. Gelmboldtd, R. Ya. Grigorashe, S. A. Kotlyare, and G. L. Kamalove a
Shubnikov Institute of Crystallography, Russian Academy of Sciences, Leninskiœ pr. 59, Moscow, 119333 Russia e-mail: [email protected] b Institute of Applied Physics, Academy of Sciences of Moldova, Academiei 5, Chisinau, MD-2028 Moldova e-mail: [email protected] c Odessa State Environmental University, Ministry of Education and Science and National Academy of Sciences of Ukraine, ul. Lvivska 15, Odessa, 65016 Ukraine e-mail:[email protected] d Physicochemical Institute for Human and Environmental Protection, Ministry of Education and Science and National Academy of Sciences of Ukraine, ul. Preobrazhenskaya, Odessa, 65026 Ukraine e-mail: [email protected] e Bogatsky Physicochemical Institute, National Academy of Sciences of Ukraine, Lyustdorfskaya dor. 86, Odessa, 65080 Ukraine e-mail: [email protected] Received April 24, 2007
Abstract—Two isostructural complexes of dioxonium [H5O2]+ with tetrabenzo-30-crown-10 of the compositions [(tetrabenzo-30-crown-10 · H5O2)][TaF6] (I) and [(tetrabenzo-30-crown-10 · H5O2)][NbF6] (II) are studied using X-ray diffraction. The complexes crystallize in the monoclinic crystal system (space group C 2/c, Z = 4). The unit cell parameters of these compounds are as follows: a = 15.6583(12) Å, b = 15.2259(13) Å, c = 16.4473(13) Å, and β = 99.398(6)° for complex I and a = 15.7117(12) Å, b = 15.2785(15) Å, c = 16.5247(15) Å, and β = 99.398(7)° for complex II. These complexes belong to the ionic type. The dioxonium cation [H5O2]+ in the form of the two-unit cluster [H3O · H2O]+ is stabilized by the strong hydrogen bond OH···O [O···O, 2.353(4) Å] and encapsulated by the crown ether. Each oxygen atom of the dioxonium cation also forms two oxygen bonds O···O(crown). The crown ether adopts an unusual two-level (pocket-like) conformation, which provides a complete encapsulation of the oxonium associate. The interaction of the cationic complex with the anion in the crystal occurs through contacts of the C–H···F type. PACS numbers: 61.66.Hq DOI: 10.1134/S1063774508020120
INTRODUCTION As is known, crown ethers (CEs) have been used in the processes of extraction concentration and separation of different metals from acidic aqueous solutions. In this respect, information on the composition and structure of the corresponding extracted forms, i.e., host–guest complexes of crown ethers with metal or hydroxonium cations, is of particular interest [1–3]. In the latter case, the anionic metal complex acts an outersphere counterion. The selectivity of the complex formation in the host–guest system is an important characteristic from the viewpoint of the practical technology. This characteristic is determined by the stereochemical features, as well as by the structure and composition (
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