Pentafluorides preparation

Chloro(trimethylsilyl)amino Tellurium Pentafluoride3 5.14 g (16.7 mmol) of dichloroamino tellurium pentafluoride, prepared from trimethylsilylamino tellurium pentafluoride and chlorine fluoride3, are dissolved in 10 m/ of fluorotrichloromethane, 2.75 g (18 mmol) of bromotrimethylsilane are added dropwise under protection from moisture, and the resultant solution is slirred at 20° for 2 h. The components of the mixture are separated by several trap-to-trap distillations with traps at —30°, —78°, and — 136° yield 3.17 g (55%) b.p. -3070.007 torr. 

E.D. Whitney, R.O. MacLaren, C.E. Fogle and TJ. Hurley, Solvolysis Reactions in Chlorine Trifluoride and Bromine Pentafluoride Preparation of the Tetrafluorochlorates and Hexafluorobromates of Potassium, Rubidium and Cerium, J. Am. Chem. Soc. 86 (1964) 2583-2586. 

Sulphur-Oxygeii-Halogen Compounds.—Chemical analysis of a relatively stable complex of methyl fluoride-antimony pentafluoride, prepared from solution in SO2, showed it to contain bonded SO2. A reinvestigation of the solution of the MeF-SbFs system in SO2 and in SO2CIF revealed that both SO2 and SO2CIF may be O-methylated, giving stable non-exchanging ions (5) and (6). 

Uranium pentafluoride prepared in the above maimer is the low-temperature, form, which can be identified by its characteristic X-ray powder pattern. The single<rystal structure has been determined tetragonal symmetry, space group I42d(Z = 8), with eight-coordination and a geometry intermediate between a dodecahedron and a square antiprism. Uranium pentafluoride is air sensitive and disproportionates in water to give a precipitate of uranium tetrafluoride and a solution of uranyl fluoride. Consequently, UFs must be handled in an inert atmosphere. The near-infrared-visible spectrum of uranium pentafluoride in acetonitrile has been determined and is perhaps the most convenient characterization. 

In eontrast, dialkylhalonium salts sueh as dimethylbromonium and dimethyliodonium fluoroantimonate, whieh we prepared from excess alkyl halides with antimony pentafluoride or fluoroantimonie acid and isolated as stable salts (the less-stable chloronium salts were obtained only in solution), are very effective alkylating agents for heteroatom eompounds (Nu = R2O, R2S, R3N, R3P, ete.) and for C-alkylation (arenes, alkenes). 

Arsenic pentafluoride can be prepared by reaction of fluorine and arsenic trifluoride or arsenic from the reaction of NF O and As (16) from the reaction of Ca(FS02)2 and H AsO (17) or by reaction of alkaH metal or alkaline-earth metal fluorides or fluorosulfonates with H AsO or H2ASO2F (18). 

The halogen fluorides are binary compounds of bromine, chlorine, and iodine with fluorine. Of the eight known compounds, only bromine trifluoride, chlorine trifluoride, and iodine pentafluoride have been of commercial importance. Properties and appHcations have been reviewed (1 7) as have the reactions with organic compounds (8). Reviews covering the methods of preparation, properties, and analytical chemistry of the halogen fluorides are also available (9). 

The halogen fluorides are best prepared by the reaction of fluorine with the corresponding halogen. These compounds are powerful oxidising agents chlorine trifluoride approaches the reactivity of fluorine. In descending order of reactivity the halogen fluorides are chlorine pentafluoride [13637-63-3] 1 5 chlorine trifluoride [7790-91-2] 3 bromine pentafluoride [7789-30-2], BrF iodine heptafluoride [16921 -96-3], chlorine... 

A mixed valency pale yeHow crystalline iron pentafluoride heptahydrate, FeF 7H20, is prepared by dissolving iron powder in 40% HF in the presence of air (16). No appHcations have been reported for this material. 

The compounds phosphoms trifluoride [7783-55-3] PP35 phosphoms pentafluoride [7647-19-0] PP55 phosphoms oxyfluoride [13478-20-17, POF and phosphoms thiofluoride [2404-52-6] were prepared prior to 1900. The most widely studied of these are PF and PF. Physical properties are... 

Niobium Penta.fIuoride, Niobium pentafluoride is prepared best by direct fluorination of the metal with either fluorine or anhydrous hydrofluoric acid at 250—300°C. The volatile NbF is condensed in a pyrex or quartz cold trap, from which it can be vacuum-sublimed at 120°C to yield colorless monoclinic crystals. It is very hygroscopic and reacts vigorously with water to give a clear solution of hydrofluoric acid and H2NbOF ... 

Fluorides. Tantalum pentafluoride [7783-71-3] TaF, (mp = 96.8° C, bp = 229.5° C) is used in petrochemistry as an isomerization and alkalation catalyst. In addition, the fluoride can be utilized as a fluorination catalyst for the production of fluorinated hydrocarbons. The pentafluoride is produced by the direct fluorination of tantalum metal or by reacting anhydrous hydrogen fluoride with the corresponding pentoxide or oxychloride in the presence of a suitable dehydrating agent (71). The ability of TaF to act as a fluoride ion acceptor in anhydrous HF has been used in the preparation of salts of the AsH, H S, and PH ions (72). The oxyfluorides TaOF [20263-47-2] and Ta02F [13597-27-8] do not find any industrial appHcation. 

Antimony pentafluoride may be prepared by fluorination of SbF or by treatment of SbCl with HF. In the latter method the fifth chlorine is removed with difficulty failure to remove the chlorine completely results in contamination of the distilled SbF with Sb(III) (27). 

Arsenic Halides. Arsenic forms a complete series of trihaUdes, but arsenic pentafluoride is the only well-known simple pentahaUde. AH of the arsenic haUdes, the physical properties of which are given in Table 2, are covalent compounds that hydrolyze in the presence of water. The trihaUdes form pyramidal molecules similar to the trivalent phosphoms analogues and may be prepared by direct combination of the elements. 

No tniodoarsorane has been reported. Triduorodiphenylarsorane [2357-18-8] C22H2QASF2, has been prepared by several methods. One method involves the reaction of benzene with arsenic pentafluoride and subsequent treatment of the resulting salt with cesium fluoride (147) ... 

Bismuth Penta.fIuoride, Bismuth(V) fluoride consists of long white needles that have been shown to have the same stmcture as the body-centered, tetragonal a-polymorph of uranium hexafluoride. The density of the soHd is 5.4 g/mL at 25°C. The soHd consists of infinite chains of trans-bridged BiF polyhedra dimers and trimers are present in the vapor phase (22). Bismuth pentafluoride may be prepared by the fluorination of BiF or... 

Bromine monofluoride [13863-59-7], BrF, can be prepared by the direct reaction of Br2 and F2, but because it readily disproportionates it has never been prepared in pure form (57). However, BrF can be prepared in situ by the reaction of Br2 with AgF in benzene (58) or by the reaction of A/-bromoacetamide and HF in ether (59). BrF adds to simple alkenes at room temperature to give products of trans-addition. Bromine trifluoride [7787-71-5], BrF, can be formed from gaseous fluorine and Hquid bromine (60). Bromine pentafluoride [7789-30-2], BrF, is formed from the reaction of BrF vapor with gaseous fluorine at 200°C (60). The tri- and pentafluorides are commercially available. As strong fluorinating agents they are useful in... 

Tetrakis(trifluoromethyl)dithietane is generated by dimerization of hexa-fluorothioaeetone which is prepared in situ from hexafluoiopropylene with potassium fluoride and sulfur [189] or with sulfur and antimony pentafluoride [190] (equation 27)... 

Until fairly recently only the pentafluorides and SbCE were known, but the exceedingly elusive AsCE was finally prepared in 1976 by ultraviolet irradiation of AsCE in liquid CE at — 105°C. Some properties of the 5 pentahalides are given in Table 13.9. 

Ti, Zr, Hf, Th, U and the pentafluorides of Nb and Ta). However, many higher fluorides require the use of a more aggressive fluorinating agent or even F2 itself. Typical of the fluorides prepared by oxidative fluorination with F2 are ... 

The pentafluorides of Rh and Ir may be prepared by the deliberate thermal dissociation of the hexafluorides. They also are highly reactive and are respectively dark-red and yellow solids, with the same tetrameric structure as [Rup5]4 and [Osp5]4 (p. 1083). 

Preparation. A compd C2F6N2 was reported in 1936 among the prods of the action of F on Ag cyanide (Ref 2), but the structure was not proved until 1940, when it was prepd in good yield by the action of 1 pentafluoride on I cyanide (Ref 4). Since then it has been prepd as the major prod from the action of Ag di-fluoride on cyanogen chloride (Refs 6 10) by the interaction of Cl, Na fluoride, and cyanogen chloride in a sealed tube at 50° for 1 hour (Refs 9 10) and in low yields by the fluori-nation of ethylene diamine or ethyleneimine (Ref 7)... 

Attempts to prepare Cd2(AsFj)2 and Cd2(SbF5)2 by reacting Cd with the corresponding pentafluoride in liq SO2 yield only Cd(II) products, unlike the analogous reaction of Hg. More successful is the use of AsFj as a solvent. When Cd is oxidized with ASF5 in liq AsFj the expected product of Cd2(AsFft)2 is not formed, but a derivative of Cdj is obtained quantitatively ... 

Few 1-benzothiophene-S-oxides 218 were obtained in moderate yields by treatment of 1-arylacetylenes 219 with sulfur dioxide and benzene in the presence of antimony pentafluoride (equation 127). A series of cyclic sulphoxides have been prepared by hydrolysis of the corresponding alkoxy sulphonium salts 220 " (equation 128). Syn-sulphoxide 221 was obtained in a low yield (15-20%) in the reaction of the dianion of cyclooctatetraene 222 with thionyl chloride (equation 129). 

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