Niobium III chloride

Niobium(III) chloride-Dimethoxyethane, NbCl3 DME (1). This soluble Nb(III) reagent is obtained as a brick-red solid by reduction of NbCl> in DME with Bu,SnH. 

Oxidation-Reduction Titrations. The extent of reduction resulting from reaction of niobium (V) chloride and bromide with pyridine was determined by indirect titration of crude reaction mixtures with standard ammonium tetrasulfato-cerate(IV) solution. Samples were stirred overnight in a stoppered flask with an excess of iron (III) ammonium sulfate. Any iron (II) formed by reaction with the niobium complex mixture was then titrated with the standard tetrasulfato-cerate(IV) solution using ferroin as indicator. Results of these determinations are given in Table III. 

Samples of the niobium (V) chloride or niobium (V) bromide-pyridine reaction mixtures were hydrolyzed in concentrated hydrochloric acid. Aliquots were diluted and neutralized with sodium carbonate to a pH of approximately 8. Sodium tetraphenylborate(III) solution then was added and a precipitate of l-(4-pyridyl) pyridinium tetraphenylborate(III) was produced. The precipitate was filtered and extracted with concentrated hydrochloric acid. The ultraviolet absorption spectrum of the extract is shown in Figure 3 for comparison with the spectrum of a known sample of l-(4-pyridyl) pyridinium dichloride in dilute hydrochloric acid. 

Preparation of Niobium (Tantalum) Chloride and Purification from Iron Impurities. Assemble an apparatus as shown in Fig. 124. Place activated carbon preliminarily dried in vacuum during two hours at 200-250 Cinto section III of the reactor. Mix 2 g of niobium (tantalum) and 0.5 g of iron in a porcelain boat and place them in section I. Fill columns 5 and 6 with a mixture of glass wool and phosphoric anhydride, and fill wash bottle 7 with sulphuric acid. 

Niobium(III) halides are known, notably the chloride, NiCl3. which is of particular interest because its solution has been shown to contain Nb + ions (in equilibrium with NbCl, 3- complex 10ns),... 

The form of molybdenum(IV) chloride obtained by the above method has been labeled the low-temperature a-isomer because of its structural similarity with the other tetrachlorides of tungsten, niobium, and tantalum and to distinguish it from the higher-temperature /8-isomer prepared from molybdenum(III) chloride and molybdenum(V) chloride. The /3-isomer may be obtained by heating the low-temperature form at 250°C. in a sealed tube with molybdenum(V) chloride for 24 hours. The excess molybdenum (V) chloride is sublimed away at 125°C. Because of its structural difference, the /S-isomer possesses a considerably higher paramagnetism and thermal stability than the a-isomer. 

The properties of vanadium (III) chloride, niobium (V) chloride, molybdenum(V) chloride, and tungsten(VI) chloride have been previously described. 

Q4Nj04Rh2CsH32, Rhodium(III), dichloro-bis(l,2-ethanediamine)-, chloride perchlorate (2 1 1), 24 229 Q4Nb2P2C3oH24, Niobium(III), hexachloro-bis[ 1,2-ethanediyIbis(dipheny Iphos-phine)]di-, 21 18... 

Nb2Cl8S3Ci6H,8, Niobium(III), di-p-chloro-tetrachloro-)jL-(dimethylsulfide)-bis(dimethyl sulfide)di-, 21 16 NdCb, Neodymium chloride, 22 39 NdF,8N606Pi2C72H72, Neodymium(III), hex-akis(diphenylphosphinic amide)-, tris(hexafluorophosphate), 23 180 NdN30i3C8Hi6, Neodymium(III), trini-trato( 1,4,7,10-tetraoxacyclododecane)-, 23 151... 

ClfJ i SjCtHu, Niobium(III), di- x-chloro-tct-rachloro- x-(dimcthyl sulfide)-bis-(dimethyl su fide)di-, 21 16 Cl7CsPr2, Cesium praseodymium chloride,... 

TRIOXAPENTADECANE (112-73-2) C12H26O3 Combustible liquid (flash point 245°F/118°C oc autoignition temp 590°F/310°C Fire Rating 1). Reacts violently with oxidizers, permanganates, peroxides and hydroperoxides, ammonium persulfate, bromine dioxide, sulfuric acid, nitric acid, perchloric acid, and other strong acids Lewis acids including aluminum chloride, boron trifluoride, iron(III) chloride, niobium pentachloride, and ytterbium(III) triflate. Incompatible with acyl halides. 

Niobium(V) chloride CljNb 205.8 33.9 Praseodymium(III) chloride CljPr 786 50.6... 

Niobium (V) chloride (10mol%) can efficiently catalyze the acetylation of 4-me-thoxybenzyl alcohol (175) with acetic anhydride at room temperature to give the corresponding acetate (176) in 96% yield (Scheme 16.51) [61]. Secondary, tertiary, phenol, as well as Baylis-Hillmann alcohol sensitive toward Lewis acids, are readily to be acetylated (Scheme 16.52). Manganese(III) acetylacetonate derivatives also proved to be effective catalysts for alcohols, amides, and phenols with acetic anhydride [62]. 

Mild oxidant agents often permit oxidations with retention of the cluster structures. One example of this kind of simple chemical electron-transfer reactions are the oxidations of niobium and tantalum clusters [M6Xi2] to the species with charges 3+ and 4+. The reaction with iron(III) chloride and cerium (IV) salts leads directly to the cations [M6Xi2] . ... 

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