K. Lutar, B. Žemva
Sep 1, 1991
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Journal
Journal of Fluorine Chemistry
Abstract
Abstract In the system chromium(V) fluoride — xenon(II) fluoride besides of already known XeF2·2CrF4 [1] also a new blue xenon(II) fluorochromate(IV) was isolated by the reaction: CrF5 + nXeF2 → XeF2·CrF4 + 1 2 XeF4 + (n−1.5)XeF2. This compound was obtained also by the reaction: CrF4 + nXeF2 → XeF2·CrF4 + (n−1)XeF2. Xenon difluoride is not able to oxidize chromium above 3+ oxidation state. Brick red XeF6·CrF4 [2] was isolated in the system chromium fluorides (CrFx with x being 2, 3, 4, 5) — xenon hexafluoride. It is observed that CrF5 is reduced to 4+ oxidation state even in oxidative environmnet of xenon hexafluoride. Although considered as a relatively strong Lewis acid, CrF5 is not strong enough to form its XeF5+ salt. From vibrational spectra it could be concluded that XeF2·CrF4 is XeF+ salt and XeF6·CrF4 is XeF5+ salt. The anionic parts of both spectra are similar. In the system chromium fluorides-krypton difluoride only chromium pentafluoride is obtained. A new method [3] designed for the preparation of polymeric in AHF insoluble binary fluorides was used for the preparation of CrF4. Its magnetic measurements indicate strong interactions between chromium atoms.