ISSN:
0044-2313
Keywords:
Chemistry
;
Inorganic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Description / Table of Contents:
Crystal Structures of Acid Hydrates and Oxonium Salts. XX. Oxonium Tetrafluoroborates H3OBF4, [H5O2]BF4, and [H(CH3OH)2]BF4The crystal structures of three oxonium tetrafluoroborates were determined. H3OBF4, oxonium tetrafluoroborate proper, is triclinic with space group P1, Z = 2 and the unit cell dimensions a = 4.758, b = 6.047, c = 6.352 Å and α = 80.40, β = 79.48, γ = 88.25° at -26°C. Cations H3O+ and anions BF4- are linked by hydrogen bonds O—H…F into ribbons of condensed rings. In [H5O2]BF4 (diaquohydrogen tetrafluoroborate, monoclinic, P21/c, Z = 4, a = 6.584, b = 9.725, c = 7.084 Å, β = 95.15° at -100°C) the hydrogen bond in the cation H5O2+ is 2.412 Å short, asymmetric and approximately centered and the linking of cations and anions three-dimensional. In [H(CH3OH)2]BF4 (Bis(methanol)hydrogen tetrafluoroborate, monoclinic, P21/c, Z = 4, a = 5.197, b = 14.458, c = 9.318 Å, β = 94.61° at -50°C) the cation [H(CH3OH)2]+ is characterized for the first time in a crystal structure with an again very short (2.394 Å), asymmetric and effectively centered hydrogen bond. By further hydrogen bonds cations and anions form only dimers of the formula unit of centrosymmetric cyclic structure.
Notes:
Die Kristallstrukturen von drei Oxoniumtetrafluoroboraten wurden bestimmt. H3OBF4, Oxoniumtetrafluoroborat im engeren Sinn, kristallisiert triklin mit der Raumgruppe P1, Z = 2 und den Gitterkonstanten a = 4,758, b = 6,047 c = 6,352 Å und α = 80,40 β = 79,48, γ = 88,25° bei -26°C. Kationen H3O+ und Anionen BF4- sind durch Wasserstoffbrücken O—H…F zu Bändern aus kondensierten Ringen verknüpft. 1m [H5O2]BF4 (Diaquohydrogentetrafluoroborat, monoklin, P21/c, Z = 4, a = 6,584, b = 9,725, c = 7,084 Å, β = 95,15° bei -100°C) ist die Wasserstoffbrücke im Kation H5O2+ 2,412 Å kurz, asymmetrisch und annähernd zentriert und die Verknüpfung der Kationen und Anionen dreidimensional. [H(CH3OH)2]BF4 (Bis(methanol)-hydrogen-tetrafluoroborat, monoklin, P21/c, Z = 4, a = 5,197, b = 14,458, c = 9,318 Å, β = 94,61° bei -50C°) besitzt das erstmalig in einer Kristallstruktur nachgewiesene Kation [H(CH3OH)2]+ mit einer wieder sehr kurzen (2,394 Å), asymmetrischen und praktisch zentrierten Wasserstoffbrücke. Kationen und Anionen bilden durch weitere Wasserstoffbrücken nur Dimere der Formeleinheit mit zentrosymmetrischer cyclischer Struktur.
Additional Material:
5 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/zaac.19814821124
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