Tantalum pentafluoride

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. 

Hydrolysis is less violent than that of tantalum pentafluoride. 

Tantalum oxide film, 24 314 Tantalum oxides, 24 322, 334 Tantalum pentachloride, 24 335 Tantalum pentafluoride, 24 334-335 Tantalum pentoxide, electrochemical reduction of, 24 322 Tantalum powder, 24 323, 324-325 capacitor-grade, 24 326 safety of, 24 333-334 Tantalum products, world shipments of, 24 331t... 

Fairbrother and Frith [38] found that a mixture of niobium and tantalum pentafluorides would polymerise isobutene in hexane solution at -78° only in the presence of a cocatalyst, such as trichloroacetic acid. 

Reaction with hydrofluoric acid yields tantalum pentafluoride ... 

Tantalum Pentafluoride, TaFs, is the only known fluoride of tantalum, and has been successfully isolated by methods that avoid hydrolysis (1) Tantalum and fluorine are brought into reaction exactly as in the preparation of niobium pentafluoride.1 (2) Tantalum penta-chloride is treated in the cold with dry hydrofluoric add the hydrochloric acid liberated and excess of hydrofluoric add are evaporated oft, and the resulting tantalum pentafluoride is purified by redistillation in a platinum crucible between 300° and 400° C.2 (3) The double barium tantalum fluoride, 3BaF2.2TaF5, is very strongly heated in a platinum tube, one end of which is kept cold. ... 

Double Fluorides of Tantalum Pentafluoride.—When solutions of tantalum pentoxide in hydrofluoric acid are treated with solutions of the fluorides of the alkali (and other) metals, double fluorides are obtained which possess the general formula R F.TaF5, where n usually varies between 1 and 3 in the most important series n=2. These double fluorides are much more stable than tantalum pentafluoride. They were among the first tantalum compounds to recdve examination,5 and still form an important class of tantalum compounds. A study of their isomorphism with the corresponding compounds of niobium... 

The following double fluorides with tantalum pentafluoride are known ... 

Tantalum pentafluoride also forms crystalline double salts with pyridine, methylamine, and other organic bases. The following compounds with pyridine have been prepared 6 SfCgHgN.HF TaF ELO C3H5N.HF.TaF5. 

I2+ and Sb2Fn ions.790 Crystalline solids that can be formulated as I2+Sb2Fn have also been prepared by Kemmitt et al.780 by the reaction of iodine with antimony or tantalum pentafluoride in iodine pentafluoride solutions. 

Hydrolysis is less violent than that of tantalum pentafluoride. See related METAL HALIDES... 

Niobium and tantalum pentafluorides are also effective catalysts for iodofluorination of TFE, while A1C13 and ZnCl2 show no activity. 

The major use of C1F3 is in the nuclear industry which converts unclean spent fuel reprocessing, uranium metal into gaseous uranium hexafluoride. Other applications are low temperature etchant for single crystalline silicon [63,64], It is also used as a fluorinating reagent and in the synthesis of GIF and conversion of metals to metal fluorides such as tantalum and niobium metals to tantalum pentafluoride and niobium pentafluoride, respectively. 

The blue solid prepared by Rulf et al. (9) in 1906 and thought to be (SbF5)aI was probably a mixture of an la fluoroantimonate salt, and some Sb(III)-containing material. Pure crystalline la SbaFu has recently been prepared by the reaction of iodine with antimony pentafluoride in liquid sulfur dioxide as solvent (11). After removal of insoluble SbFg, deep blue crystals of la SbaFi were obtained from the solution. An X-ray crystallographic structure determination showed the presence of the discrete ions la and SbaFu . Crystalline solids that can be formulated as la SbaFu and Ia TaaFii have also been prepared by Kemmitt et al. (4) by the reaction of iodine with antimony or tantalum pentafluorides in iodine pentafluoride solutions. 

Fluorine forms tantalum pentafluoride, TaF6, which resembles the columbium salt, being known only in solution. It forms important double fluorides. 

TaF5 TANTALUM PENTAFLUORIDE 1599 ThF4[g] THORIUM TETRAFLUORIDE (GAS) 1650... 

TaF5[g] TANTALUM PENTAFLUORIDE (GAS) 1600 ThH2 THORIUM DIHYDRIDE 1650... 

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