Niobium oxytrichloride

Other niobium-hydrogen compounds or alloys of doubtful composition have been obtained by reduction of niobium oxytrichloride, NbOCl3, with hydrogen,7 and by using metallic niobium as the cathode in the electrolysis of dilute sulphuric acid.8... 

Niobium Trichloride, NbCl3, is prepared by leading the vapour of niobium pentachloride through a heated tube.4 It is also formed in small quantity by the action of carbon tetrachloride vapour on niobium pentoxide contained in a hard-glass tube, and has probably been prepared in solution by the electrolytic reduction of the pentachloride.4 It forms a black, crystalline crust with an almost metallic lustre, which closely resembles the appearance of a film of sublimed iodine. It is not decomposed by water or ammonia, but is readily oxidised by dilute nitric add to niobium pentoxide. On being heated to a red heat in an atmosphere of carbon dioxide, a sublimate of niobium oxytrichloride, NbOCl3, is produced, the carbon dioxide undergoing reduction to the monoxide. 

Niobium Oxychlorides.—The most important niobium oxy-chlorine compound is niobium oxytrichloride, NbOCl8, which is described below. 

Niobium Oxytrichloride, NbOCls.—This compound is of historical interest in that it was one of the oxy-halogen compounds prepared originally by Rose in which the oxygen atom was overlooked. Rose called this substance hyponiobium chloride its correct formula, and hence the true valency of niobium, were first established by Blomstrand.4... 

Niobium oxytrichloride is prepared by the action of chlorine on a mixture of niobium pentoxide and carbon, or on the lower oxide, NbO 5 or by the action of the vapours of carbon tetrachloride on the pentoxide. Some niobium pentachloride is produced in the same reaction, and this is removed either by distilling it away at the lowest temperature possible in an atmosphere of carbon dioxide, or by subliming the product in a current of chlorine over the ignited oxide.7 The oxychloride has also been prepared by passing the vapours of niobium pentachloride over niobium pentoxide at a red heat.8... 

Double Saits of Niobium Omytribromide.—These correspond exactly to the double salts of niobium oxytrichloride described above, and are prepared by analogous methods. The following are known 1... 

Oxysulphides.—The action of carbon bisulphide vapour or hydrogen sulphide on niobium pentoxide, sodium niobate or niobium oxytrichloride gives rise to a black powder which assumes a metallic appearance on being rubbed, and which conducts electricity well. This is probably an oxysulphide of niobium, Nba.OJ,Sz, but its exact composition varies with the experimental conditions, and its individuality is a matter of doubt.5 Oxysulphides of niobium of doubtful composition, mixed with potassium sulphide, are also produced by the action of carbon bisulphide vapour on potassium oxalo-niobate. ... 

Niobium oxytrichloride is also present, as a result of hydrolysis of the pentachloride or reaction with oxygen at any of the previous stages, owing to the presence of traces of moisture or air, i.e. 

Write balanced chemical equations for each of the following verbal descriptions (a) Vanadium oxytrichloride (VOCI3) is formed by the reaction of vanadium(lll) chloride with oxygen, (b) Niobium(V) oxide is reduced to the metal with hydrogen gas. (c) Iron(lll) ion in aqueous solution is reduced to iron(ll) ion in the presence of zinc dust, (d) Niobium(V) chloride reacts with water to yield crystals of niobic acid (HNb03). 

---