ISSN:
0044-2313
Keywords:
Chemistry
;
Inorganic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Description / Table of Contents:
Hydrogen Bonds in Fluorine Containing Solids. I. Preparation, Properties, and Crystal Structure of (NH4)2[Cr(H2O)6]F5The new red chromium(III) fluorine compound diammonium hexa-aqua chromium(III) pentafluoride has been prepared from solution and investigated by spectroscopic and magnetic methods. Single crystal investigations showed a monoclinic unit cell with hexagonal metric (space group C2/c): a = 11.997(1) Å, b = 6.928(1) Å, c = 13.574(2) Å, β = 90.0° (a = b √3). As result of the X-ray structure determination (Rw = 0.023) we found three dimensional connexion of nearly regular [Cr(H2O)6]-octahedra by - O—H … F … H—O-type H bonds and an additional bridging between the F- ions by H bonds to the NH4+ ions. The NH4+ ions as well as the F- ions have tetrahedral coordination. Three different species of tetrahedral groups: [NH4(F4)], [F(NH4(H2O)3)], and [F((H2O)2(NH4)2)] may be distinguished. All hydrogen bonds are nearly linear and show very short distances O—F (2.53-2.57 Å) and N—F (2.72-2.73 Å). This novel three dimensional network of H bonds stabilizes apparently the [Cr(H2O)6] complex despite the presence of “free” fluorine ions in the crystal.
Notes:
Die neue rote Chrom(III)-Fluor-Verbindung Diammonium-hexaaquochrom(III)-pentafluorid wurde aus Lösung dargestellt und spektroskopisch sowie magnetisch untersucht. Einkristalluntersuchungen ergaben eine monokline Elementarzelle mit hexagonaler Metrik (Raumgruppe C2/c): a = 11,997(1) Å, b = 6,928(1) Å, c = 13,574(2) Å, β = 90,0°(a = b √3). Die Röntgenstrukturanalyse (Rw = 0,023) zeigte dreidimensionale Verknüpfung von nahezu regulären [Cr(H2O)6]-Oktaedern über - O—H … F … H—O-Wasserstoffbrücken und zusätzliche Verbrückung der F--Ionen über H-Brücken zu den NH4+-Ionen. Sowohl die NH4+-wie die F--Ionen sind dabei tetraedrisch koordiniert, wobei sich drei verschiedene Baugruppen: [NH4(F4)], [F(NH4(H2O)3)] und [F((NH4)2(H2O)2)] formulieren lassen. Alle H-Brücken sind nahezu linear und zeigen sehr kurze O—F-Abstände von 2,53-2,57 Å und N—F-Abstände von 2,72-2,73 Å. Dieses neuartige System von H-Brücken stabilisiert offenbar den [Cr(H2O)6]-Komplex trotz der Anwesenheit “freier” F--Ionen im Kristall.
Additional Material:
4 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/zaac.19774360103
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