Английская Википедия:Chromyl fluoride
Шаблон:Chembox Chromyl fluoride is an inorganic compound with the formula Шаблон:Chem2. It is a violet-red colored crystalline solid that melts to an orange-red liquid.[1]
Structure
The liquid and gaseous Шаблон:Chem2 have a tetrahedral geometry with C2v symmetry, much like chromyl chloride.[2] Chromyl fluoride dimerizes via fluoride bridges (as Шаблон:Chem2) in the solid state, crystallizing in the P21/c space group with Z = 4. The Cr=O bond lengths are about 157 pm, and the Cr–F bond lengths are 181.7, 186.7, and 209.4 pm. Chromium resides in a distorted octahedral position with a coordination number of 6.[3]
History and preparation
Pure chromyl fluoride was first isolated in 1952 as reported by Alfred Engelbrecht and Aristid von Grosse.[4] It was first observed as red vapor in the early 19th century upon heating a mixture of fluorspar (Шаблон:Chem2), chromates, and sulfuric acid. These red vapors were initially thought to be Шаблон:Chem2, although some chemists assumed a Шаблон:Chem2 structure analogous to Шаблон:Chem2.[4] The first moderately successful synthesis of chromyl fluoride was reported by Fredenhagen who examined the reaction of hydrogen fluoride with alkali chromates. A later attempt saw von Wartenberg prepare impure Шаблон:Chem2 by treating chromyl chloride with elemental fluorine.[5] Another attempt was made by Wiechert, who treated HF with dichromate, yielding impure liquid Шаблон:Chem2 at −40 °C.
Engelbrecht and von Grosse's synthesis of Шаблон:Chem2, and most successive syntheses, involve treating chromium trioxide with a fluorinating agent:[4]
The reaction is reversible, as water will readily hydrolyze Шаблон:Chem2 back to Шаблон:Chem2.
The approach published by Georg Brauer in the Handbook of Preparative Inorganic Chemistry[6] drew on von Wartenberg's approach[5] of direct fluoridation:
Other methods include treatment with chlorine fluoride, carbonyl fluoride, or some metal hexafluorides:
- Шаблон:Chem2
- Шаблон:Chem2
- Шаблон:Chem2 (M = Mo, W)
The last method involving the fluorides of tungsten and molybdenum are reported by Green and Gard to be very simple and effective routes to large quantities of pure Шаблон:Chem2.[1] They reported 100% yield when the reactions were conducted at 120 °C. As expected from the relative reactivities of Шаблон:Chem2 and Шаблон:Chem2, the molybdenum reaction proceeded more readily than did the tungsten.[7]
Reactions
Chromyl fluoride is a strong oxidizing agent capable of converting hydrocarbons to ketones and carboxylic acids. It can also be used as a reagent in the preparation of other chromyl compounds.[1] Like some other fluoride compounds, Шаблон:Chem2 reacts with glass and quartz, so silicon-free plastics or metal containers are required for handling the compound. Its oxidizing power in inorganic systems has also been explored.[8] Chromyl fluoride can exchange fluorine atoms with metal oxides.
Chromyl fluoride will also convert the oxides of boron and silicon to the fluorides.[8]
Chromyl fluoride reacts with alkali and alkaline earth metal fluorides in perfluoroheptane (solvent) to produce orange-colored fluorochromates:[8]
Chromyl fluoride also reacts with Lewis acids, drawing carboxylate ligands from organic acid anhydrides and producing an acyl fluoride byproduct:[8]
Chromyl fluoride forms adducts with weak bases NO, Шаблон:Chem2, and Шаблон:Chem2.
References
- ↑ 1,0 1,1 1,2 Gard, G. L. (1986) "Chromium Difluoride Dioxide (Chromyl Fluoride)," Inorg. Synth., 24, 67-69, Шаблон:Doi.
- ↑ Hobbs, W. E. (1958) "Infrared Absorption Spectra of Chromyl Fluoride and Chromyl Chloride," J. Chem. Phys. 28(6), 1220-1222, Шаблон:Doi.
- ↑ Supeł, J.; Abram, U.; Hagenbach, A.; Seppelt, K. (2007) "Technetium Fluoride Trioxide, TcO3F, Preparation and Properties." Inorg. Chem., 46(14), 5591–5595, Шаблон:Doi.
- ↑ 4,0 4,1 4,2 Engelbrecht, A.; von Grosse, A. (1952) "Pure Chromyl Fluoride," J. Am. Chem. Soc. 74(21), 5262–5264, Шаблон:Doi.
- ↑ 5,0 5,1 von Wartenberg, H. (1941) "Über höhere Chromfluoride (Шаблон:Chem, Шаблон:Chem und Шаблон:Chem)" [About higher chromium fluorides (Шаблон:Chem, Шаблон:Chem and Шаблон:Chem)], Z. Anorg. Allg. Chem. [in German], 247(1-2), 135–146, Шаблон:Doi.
- ↑ Ошибка цитирования Неверный тег
<ref>; для сносокBrauerне указан текст - ↑ Green, P. J.; Gard, G. L. (1977) "Chemistry of Chromyl Fluoride. 5. New Preparative routes to CrO2F2," Inorg. Chem. 16(5), 1243–1245, Шаблон:Doi.
- ↑ 8,0 8,1 8,2 8,3 Brown, S. D.; Green, P.J.; Gard, G.L. (1975) "The Chemistry of Chromyl Fluoride III: Reactions with Inorganic Systems," J. Fluorine Chem. 5(3), 203-219, Шаблон:Doi.
