Molybdenum trioxide complexes

Molybdenum hexafluoride. 3,1412 Molybdenum-iron-sulfur complexes, 4,241 Molybdenum oxide amino acid formation prebiotic systems, 6, 872 Molybdenum storage protein microorganisms, 6, 681 Molybdenum telluride, 3, 1431 Molybdenum tetraalkoxides physical properties, 2, 347 Molybdenum tribromide, 3,1330 Molybdenum trichloride, 3,1330 Molybdenum trifluoride, 3, 1330 Molybdenum trihalides, 3, 1330 bond lengths, 3, 1330 magnetic moments, 3,1330 preparation, 3,1330 properties, 3, 1330 structure, 3,1330 Molybdenum triiodide, 3,1330 Molybdenum trioxide complexes, 3, 1379 Molybdenum triselenide, 3, 143)... 

Derivation By the action of sodium hydroxide on molybdenum trioxide. Complex molybdates are prepared by dissolving large amounts of molybdenum trioxide in solutions of normal molybdates. 

Molybdenum(III) complexes include the molybdenum trihaUdes. Molybdenum trichoride [13478-18-7], trifluoride [20193-58-2], tribromide [13446-57-6], and ttiiodide [14055-75-5] are all known. The oxide dimolybdenum trioxide [1313-29-7], M02O2, and the seldom-studied sulfide analogue [12033-33-9], M02S2, are formally trivalent. 

Molybdenum trioxide, intercalation into, 12, 823 Molybdocenes, as anticancer agents, 1, 892 MOMNs, see Metal-organometallic coordination networks Monisocyanides, with silver(I) complexes, 2, 223 Monitoring methods, kinetic studies, 1, 513 Mono(acetylacetonate) complexes, with Ru and Os halfsandwich rf-arenes, 6, 523 tj2-Monoalkene monodentate ligands, with platinum divalent derivatives, 8, 617 tetravalent derivatives, 8, 625 theoretical studies, 8, 625 zerovalent derivatives, 8, 612... 

Molybdenum trioxide (M0O3) deposited on silica was one of the first supported Mo catalysts to be prepared. In contrast to Ti/SiC>2, which is used industrially, Mo/SiC>3 did not break through commercially, mainly owing to substantial leakage of Mo under catalytic conditions. Trifiro et al. (213) showed that when M0O3 on silica is used for the epoxidation of cyclohexene with t-BuOOH in benzene at 353 K, part of the activity originates from dissolved Mo. The main reason why Mo is not entirely retained on silicas and aluminas is thought to be the formation of soluble neutral Mo-diol complexes. 

Molybdates.—Normal molybdates of the type R aMoO., exist in solution but are relatively unstable, and readily form acid salts or complex polymolybdates. Thus dimolybdates, R aMogOy, can be obtained by fusion of molybdenum trioxide with sodium or potassium nitrate trimolybdates, R gMojOio, and tetramolybdates, R Mo Oig, by heating molybdenum trioxide with an aqueous solution of sodium or potassium carbonate. Even more highly acid salts—for example, octa- and deca-molybdates—can be obtained. Solutions of normal molybdates, when treated with hj droehlorie add or nitric acid, yield a precipitate of acid molybdate this reaction does not, however, take place with sulphuric, acetic, oxalic, or tartaric acids. 

Molybdates combine also with other acidic oxides, forming a series of complex molybdates, the most important of which are probably the phosphomolybdates (see p. 163). The formation of such compounds as diehlormolybdic acid or molybdenum hydroxychloride, MoOCl2(OH)2 (see p. 126), and the sulphate M0O3.SO3 (see p. 160), illustrate the behaviour of molybdenum trioxide as a basic oxide. 

Preparation. Mimoun et at.1 prepared this complex of Mo05 and HMPT by dissolving molybdenum trioxide (M0O3, ROC/RIC, 50 g.) at 40° in 30 % H 202 (250 cc.). The yellow solution so obtained is cooled to 10° and HMPT (62.3 g.) is added with efficient stirring. A yellow precipitate is formed immediately and is collected on a filter and washed several times with ether. The dried material is crystallized twice from methanol it is obtained as yellow crystals in 84% yield. The French chemists showed that the complex has the structure shown in formula (1). 

Ammonium oxymolybdenum complexes with amines These complexes are prepared by the acid/base reaction of an acidic molybdenum source such as molybdenum trioxide, molybdic acid, ammonium molybdate [41] and ammonium thiomolybdates with oil-soluble amines [42], The preferred aminic compounds are lubricant additives known as dispersants, examples being succinimides and Mannich-type bases, as in Reactions (4.42) and (4.43) [41] ... 

Smoke suppression in rigid PVC can also be accomplished by the utilisation of a copper and molybdenum complex. A binary mixture of cuprous oxide and molybdenum trioxide reduces total smoke production, the average extinction area and smoke production rate. Increased char is formed and a reduced level of flammability in the PVC. 

Molybdenite (M0S2) forms soft, thin flakes, which are very similar to graphite. Molybdenum trioxide (M0O3) is a white powder that is yellow in heat and insoluble in water and most acids. It is easily soluble in alkaline solution, with molybdates being formed. Ammonium molybdate together with phosphates forms a yellow-colored complex and precipitates in nitric acid solutions. If acidified molybdate solutions are treated with reducing agents, they become deep blue (molybdenum blue). Both reactions are used in the colorimetric determination of phosphorus. 

In one purification process (U.S Patent 3,202,481) potassium or sodium permanganate is used to oxidize the impurities Other oxidizing agents also can be used, such as persulfates or chlorates Molybdenum trioxide is used to form a complex with the oxidized phosphorus impurities. The nitric acid is contacted with the oxidizing agent and the molybdenum compound at the boiling point of the acid, and the acid is continuously removed by distillation. The oxidized impurities remain in the residue. As a result, the purified acid will contain less than 0.5 ppb by weight of arsenic and phosphorus. 

Ephraim and Muller 2 describe some results obtained with the groups — S04, — Se04, —Mo04, — W04, and —Cr04. These anions were united with the hexammino-nickel complex, and the temperature measured at which the ammonia tension is equal to atmospheric pressure. The stability of the complex is apparently independent of the atomic volumes of selenium, sulphur, chromium, molybdenum, and tungsten, but increases proportionally with the molecular volume of the corresponding trioxides. 

Addition of fillers such as alumina trihydrate, antimony trioxide, molybdenum oxide [315], zinc borate and zinc borate complex [316] leads to increase in TS but decrease in elongation and NG migration/absorption. Addition of inorganic fillers also leads to increase in flame retardance. 

Trivalent molybdenum is found in a few simple compounds. The black hydroxide, Mo(OH)3, dissolves in acids -with salt formation, yielding reddish-purple solutions which darken in colour. Upon evaporation crystalline salts are not obtained, but when the solution is taken to dryness a greyish-black residue remains, which can be redissolved in water to a dark grey solution. This may be accounted for by the readiness with which the salts undergo hydrolysis, with formation of the black hydroxide, possibly in the eoUoidal form. The similarity of molybdenum to chromium is seen in the series of complex For indications of basic properties in the trioxide, see p. 137. 

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