Vanadium trichloride

Commercial production from petroleum ash holds promise as an important source of the element. High-purity ductile vanadium can be obtained by reduction of vanadium trichloride with magnesium or with magnesium-sodium mixtures. 

Vanadium(III) Chloride. Vanadium(III) chloride (vanadium trichloride, VCl ) is a pink-violet sohd, is readily hydrolyzed, and is insoluble in nonpolar solvents but dissolves in donor solvents, eg, acetonitrile, to form coordination compounds. Chemical behavior of the tribromide (VBr ) is similar to that of VCl. ... 

Halides and Oxyhalides. Vanadium(V) oxytrichloride is prepared by chloriaation of V20 mixed with charcoal at red heat. The tetrachloride (VCl is prepared by chlorinating cmde metal at 300°C and freeing the Hquid from dissolved chlorine by repeated freezing and evacuation. It now is made by chlorinating V20 or VOCl ia the presence of carbon at ca 800°C. Vanadium trichloride (VCl ) can be prepared by heating VCl ia a stream of CO2 or by reaction of vanadium metal with HCl. 

In the powdered state, the metal, which is obtained by the action of magnesium on vanadium trichloride, combusts spontaneously in air. 

At 60°C, the metal reacts violently with vanadium trichloride. 

However, heating vanadium trichloride (VC13) above 400 °C causes its disproportionation according to the reaction... 

The conversion of a higher chloride to a lower chloride by hydrogen reduction has been mentioned earlier in connection with the formation of the relatively less volatile ferrous chloride from ferric chloride. This type of reaction is more general and is widely used. Vanadium trichloride can be reduced to the dichloride by hydrogen at temperatures higher than 500 °C ... 

Reaction of vanadium trichloride and similar halides with Grignard reagents is almost explosively violent under a variety of conditions. 

Some samples of vanadium prepared by magnesium reduction of vanadium dichloride or vanadium trichloride are pyrophoric. 

Caution. Tetrahydrofuran (THF) is extremely flammable and hygroscopic and forms explosive peroxides only anhydrous peroxide-free solvent should be used. Lithium wire is a hazardous substance and must be handled under strictly anaerobic conditions. Further, since it slowly reacts with dinitrogen at room temperature, lithium metal is best handled under an atmosphere of dry, oxygen-free argon. Vanadium trichloride is air-sensitive and should be transferred under an inert atmosphere. Carbon monoxide is a toxic and flammable gas and must be handled in a well-ventilated fume hood. 

The dropwise addition of sodium naphthalenide to THF containing vanadium trichloride and l,2-bis(dimethylphosphino)ethane (dmpe) causes changes of colours suggesting a stepwise reduction from +2 to 0. Brown [V(dmpe)3] was isolated41 (fieff = 2.10BM) and IR data suggest octahedral coordination. The same complex was synthesized by a metal vapour technique.42 The ESR was that expected and the unit cell is cubic with a = 11.041(3) A. 

Anhydrous vanadium trichloride or tribromide reacts with acetonitrile to yield green or red-brown solutions. Complexes [VX3(MeCN)3] (X = Cl or Br) crystallize with varying amounts of acetonitrile in the lattice,212 where the IR spectra show the free (2253.5 cm-1) and coordinated (2292 cm-1) acetonitrile. 

Vanadium trichloride or tribromide reacts with thioethers giving [VX3L2] (X = C1 or Br L = SMe2, tetrahydrothiophene or SEt2).288,289 The complex with di-n-propyl sulfide could not be isolated.288 These compounds are oxidized very easily. Solubility, molecular weights and conductance show that they are monomeric and non-ionic. Dipole moments, IR and electronic spectra are consistent with trans trigonal bipyramidal structures. 

It is of interest to note that Meyer and Backa,1 by treating vanadium trichloride and tribromide with liquid ammonia, have recently obtained hexammine derivatives ... 

These are comparable in their reactions to the hexammine of ferric chloride, [Fe(NH3)0]Cl3. ITexammino-vanadium trichloride loses its chlorine on being treated with nitric acid and forms the corresponding nitrate, [V(NH3)8](N03)3. 

Vanadous Chloride, vanadium trichloride, VC13.—This halide is obtained by the action of hydrogen chloride on finely divided vanadium at 300° to 400° C.,e or by heating vanadium tetrachloride to 140° C. in a current of carbon dioxide, which removes the chlorine formed at the same time. It can be conveniently made also by boiling vanadium oxy-trichloride, VOCl3, vanadium tetrachloride, VC14, or a mixture of both, with sulphur, under reflux. The reactions involved axe 7... 

Anhydrous vanadium trichloride is a crystalline solid of the colonr of peach blossom. It is extremely hygroscopic, deliquescing to a brown liquid. It gives green solutions in alcohol and ether. Density at 18° C., 3-00. The absorption spectrum has been studied.8 On being strongly heated in hydrogen it is reduced to vanadium dichloride, VCla,... 

Hexammino-vanadium Trichloride, [V(NH3)6]C13.—The similarity between the trichlorides of iron and vanadium is further shown in their behaviour towards ammonia. At ordinary temperatures ammonia reacts with vanadium trichloride to produce vanadium nitride, VN, and ammonium chloride, but if liquid ammonia is poured over vanadium trichloride, a quantitative yield of a reddish-brown salt, [V(NH3)6]C13, is obtained, which recalls the hexammines of cobalt and chromium. The ammonia molecules are not, however, very firmly held, and the compound is, therefore, more comparable with the corresponding hexammine of ferric chloride, [Fe(NH3)6]Cl3. 

Hexammino-vanadium trichloride is insoluble in water, alcohol, and... 

Vanadium Oxymonochloride, VOC1, can be obtained by heating vanadium trichloride in an atmosphere of carbon dioxide at about 700° C. for several hours ... 

Halogenation in the presence of sulphur, or by means of sulphur halides, is also available. When chlorine is conducted into a mixture of vanadium pentoxide and sulphur, or when powdered vanadium pentoxide is treated with sulphur monochloride vapours, an immediate reaction sets in, with formation of vanadium oxytrichloride.2 A quantitative yield of this compound is also obtained when vanadium trichloride is heated in oxygen at 500° to 600° C.3... 

It is obvious that the combustion of a molecule of vanadium with an increasing number of molecules of chlorine is not accompanied by a gradually increasing evolution of heat. The figures show that the formation of vanadium tetrachloride (liquid) from vanadium trichloride (solid) and chlorine (gas) proceeds endothermically ... 

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