Vanadium IV fluoride

The known halides of vanadium, niobium and tantalum, are listed in Table 22.6. These are illustrative of the trends within this group which have already been alluded to. Vanadium(V) is only represented at present by the fluoride, and even vanadium(IV) does not form the iodide, though all the halides of vanadium(III) and vanadium(II) are known. Niobium and tantalum, on the other hand, form all the halides in the high oxidation state, and are in fact unique (apart only from protactinium) in forming pentaiodides. However in the -t-4 state, tantalum fails to form a fluoride and neither metal produces a trifluoride. In still lower oxidation states, niobium and tantalum give a number of (frequently nonstoichiometric) cluster compounds which can be considered to involve fragments of the metal lattice. 

Great differences in product structures and product distributions are obtained by lead(IV) oxide or acetate oxidation of perfluorophenol in different solvents and media. The reaction with the former agent gives a quinoid ether in 22% yield (Table 10).173 The oxidation with lead(IV) acetate has been optimized to such a level as to give perfluoro cyclohexa-2,5-dienone (4) in 65 % yield.174 Treating the phenol with vanadium(V) fluoride or vanadium(III) fluoride as well as xenon difluoride gives a mixture of products,175 therefore, the reactions are only of minor preparative importance. 

Bis(acctonitro)chloronitropalladium(II). /-Butyl hydroperoxide-Dialkyl taitratesr-Vanadium(IV) isoproxide. t-Butylhydroperoxide-Molybdenum carbonyl. t-Butylhydroperoxide-Vanadyl acetylacetonate. [(— )-Camphor-10-ylsulfonyl]-3-aryloxaziridines. m-Chloroperbenzoic acid-Potassium fluoride. Dimethylsulfonium methylidc. 3,5-Dinitroperbenzoic acid. Hydrogen peroxide-Vilsmeier reagent. p3-Oxohexakis(p-... 

Vanadium (V, at. mass 50.94) occurs in the V, IV, III, and II oxidation states, vanadium(V) compounds being the most stable. In alkaline medium, the colourless vanadate VOs ions exist, whereas in strongly aeidic media, the yellow V02 cations are present. Within the intermediate pH range polymerized orange-yellow anionic forms occur. Vanadium(V) forms heteropoly acids with P(V), Mo(VI), and W(VI), and also peroxide complexes. Vanadium(IV) occurs as the blue vanadyl ion V02", stable in acid solutions and readily oxidized to vanadium(V) in alkaline solution. The VO cation is amphoteric. At pH 4, V0(0H)2 precipitates and at pH 9 it dissolves. Vanadium(IV) forms fluoride-, oxalate-, and... 

Methylbromoarsines, synthesis 26 Vanadium(III) fluoride, synthesis 27 Sulfur(IV) fluoride, synthesis 33 Peroxydisulfuryl difluoride, synthesis 34 Trichloro(tripyridine)chromium(III), synthesis 36 Tris(3-bromoacetylacetonato)chromium(III), synthesis 37 Trichloro(tripyridine)molybdenum(III), synthesis 39 Uranyl chloride 1-hydrate, synthesis 41 Rhenium(III) iodide, synthesis 50 Potassium hexachlororhenate(IV) and potassium hexa-bromorhenate(IV), synthesis 51 Iron-labeled cyclopentadienyl iron complexes, synthesis 54 Inner complexes of cobalt(III) with diethylenetriamine, synthesis 56... 

The cobalt complex is usually formed in a hot acetate-acetic acid medium. After the formation of the cobalt colour, hydrochloric acid or nitric acid is added to decompose the complexes of most of the other heavy metals present. Iron, copper, cerium(IV), chromium(III and VI), nickel, vanadyl vanadium, and copper interfere when present in appreciable quantities. Excess of the reagent minimises the interference of iron(II) iron(III) can be removed by diethyl ether extraction from a hydrochloric acid solution. Most of the interferences can be eliminated by treatment with potassium bromate, followed by the addition of an alkali fluoride. Cobalt may also be isolated by dithizone extraction from a basic medium after copper has been removed (if necessary) from acidic solution. An alumina column may also be used to adsorb the cobalt nitroso-R-chelate anion in the presence of perchloric acid, the other elements are eluted with warm 1M nitric acid, and finally the cobalt complex with 1M sulphuric acid, and the absorbance measured at 500 nm. 

Metal Halides. Reacts explosively or violently with the following calcium bromide iron(III) bromide or chloride iron(II) bromide or iodide cobalt(II) chloride silver fluoride all four mercury(II) halides copper(I) chloride, bromide or iodide copper(II) chloride and bromide ammonium tetrachlorocuprate zinc and cadmium chlorides, bromides, and iodides aluminum fluoride, chloride, and bromide thallium bromide tin(II) or (IV) chloride tin(IV) iodide arsenic trichloride and triiodide antimony and bismuth trichlorides, tribromides, and triiodides vanadium(V) chloride chromium(IV) chloride manganese(II) and iron(II) chlorides and nickel chloride, bromide, and iodide.17,22"25... 

The IV state. This is the most important oxidation state of Ti where the main chemistry is that of Ti02 and TiCl4 and its derivatives. This is also an important state for vanadium which forms the vanadyl ion V02+ and many derivatives, cationic, anionic, and neutral containing the VO group. For the remaining elements, Cr-Ni, the IV state is found mainly in fluorides, fluoro complex anions, and cation complexes however, an important class of compounds are the salts of the oxo ions and other oxo species. 

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