Molyb denum

Type 316-This has a composition of 17/12/2.5 chromium/nickel/molyb-denum. The addition of molybdenum greatly improves the resistance to reducing conditions such as dilute sulfuric acid solutions and solutions containing halides (such as brine and sea water). 

S)-Chloronitroso(2-methyl-2-propenyl) [(7 ,S,S)-neomenthyl]cyclopentadienyl molyb-denum (1) yields on reaction with benzaldehydc the corresponding homoallylic alcohol with > 98% ee1. 

Sample Number Molyb- denum Nickel Cobalt Iron Chro- mium Total >... 

Since studies bearing on the role of molybdenum in milk xanthine oxidase have depended heavily on the EPR method, it is convenient to precede detailed discussion by a general description of the various molyb-denum(V) EPR signals which have been obtained from the enzyme. 

Molybdenum oxytetrachloride is a dark green crystalline compound with a melting point of 100 to 101°. Infrared absorption (KBr disk) has been used to establish the absence of OH- and H20 in verification of the anhydrous state. A broad band appears in the 970-em.-1 region and reveals molyb-denum-to-oxygen bonding. The oxychloride reacts with thoroughly dried Nujol so that satisfactory infrared spectra cannot be obtained with this as a dispersion medium. When exposed to light, molybdenum oxytetrachloride forms a brown film on the surface of the ampule. Since this film is not formed when the ampules are stored in the dark, molybdenum oxytetrachloride is concluded to be photosensitive. 

Molybdenum (IV) bromide is a black crystalline solid which is very sensitive to oxidation and hydrolysis it should be handled only under a dry inert atmosphere. Its solubility in bromine at 51° is ca. 3.0 g./lOOO g. of bromine, and bromine solutions were found to be nonconductors. For example, at 25° both the solvent bromine and a 0.96 X 10 3 M solution in molybdenum (IV) bromide exhibited a specific conductance of 1.3 X 10-10 ohm-1 cm.-1 At 110 to 130° in vacuo, solid molybdenum (IV) bromide decomposes quantitatively into molyb-denum(III) bromide and bromine, and because of this thermal instability it cannot be sublimed except under a bromine atmosphere. 

OftF FeMoPCnH, Iron(l +), p-acetyl-2kC 1 -1 k O-pentacarbonyl-1 k C,2k2C-bis[l,2-(T)5-cyclopentadienyl)]molyb-denum-... 

After complete oxidation of the taken amount of molybdenite, switch off the furnace and cool the apparatus in a stream of air. Disconnect receiver 6 from the apparatus and extract the sublimed molyb-denum(VI) oxide crystals from the receiver, and also from the... 

Preparation of Potassium Hexachloromolybdate(III). Perform the experiment in a fume cupboard ) Dissolve 50 g of molybdic anhydride in 250 ml of concentrated hydrochloric acid. Spill the molyb-denum(Vl) oxide into the beaker in small portions as it dissolves during 6 hours. If the solution is turbid, filter it through a glass filter (prepare the solution beforehand). 

Table 2. Fluorination of Carbonyl Compounds with Molyb-denum(VI) Hexafluoride and Boron Trifluoride13...

Photooxidation of the Mo2+ moiety has also been demonstrated for Mo2(aq)4, Mo2Clg , Mo2 Br (244), and Mo2Cl4(PR3)4 (245). Molyb-denum(III) products are observed upon 254 nm irradiation of these complexes as opposed to the molybdenum (2.5+) species formed upon photolysis of the Mo2(S04)4 dimer. Molecular hydrogen and a hydroxy bridged Mo3 dimer are... 

Some examples have been reported of tethered r 6-arene complexes of molyb-denum(II) and tungsten(II) that incorporate oxygen as the auxiliary donor atom.37 40 Reaction of neat 2,6-diphenylphenol with [MH4(PMePh2)4] (M = Mo, W) at 150 °C gives the tethered hydrido(aryloxo)metal(II) complexes 30 and 31.36 A metal-hydride bond is probably first cleaved by the phenolic oxygen with loss of H2 coordination of the pendant arene then induces loss of another equivalent of H2. 

Schrauzer has shown that compounds derived from molyb-denum(V)-cysteine derivatives also catalyze the reduction of dinitrogen. Subsidiary experiments confirm that the active species contain molybdenumdV) rather than molybdenum Ill), the latter tending to lead to the production of dihydrogen (279). Molybdenum isonitrile derivatives can also lead to dinitrogen-reduction catalysis (252). These systems are very difficult to analyze, and they often work best at low molybdenum concentrations (<10 3 M). The intermediates cannot be isolated or detected directly. Their nature must be inferred on the basis of circumstantial evidence, and this is sometimes difficult to interpret. 

The crystal structure of trans-dichlorobis(AT-methylsalicylaldiminato)molyb-denum(iv) has been determined and the compound shown to consist of discrete monomeric units which have a crystallographic centre of symmetry. The bonds involving the metal atom, Mo—O, Mo—N, and Mo—Cl, are 195, 214, and 239 pm, respectively.437 The complex [Mo(SCN)2(H20)L] [H2L = AT-(salicylidene)-2-hydroxybenzamine] has been prepared and its i.r. and electronic spectra recorded.430... 

Hydrotreating Refining process to remove sulfur, nitrogen, and oxygen from petroleum feedstocks by contacting with hydrogen in the presence of a nickel/molyb-denum or cobalt/molybdenum on alumina catalyst. 

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