Molybdenum oxide iodide

Presumably because of its lower electronegativity, bromine can stabilize Mo(V) as MoOBr8 but not Mo (VI) as MoOBr4. There are no reported molybdenum oxide iodides and no lower-valent [molybdenum(V) or molybdenum(IV)] oxide fluorides. The combination of oxygen plus chlorine can stabilize Mo (VI) in both M0O2CI2 and MoOCU, but MoCl is apparently unstable at room temperature. 

In order to circumvent this problem the rate-determining step was bypassed by using more reactive reagents, allyl alcohol and allyl iodide. These allylic probes were expected to adsorb on the molybdenum oxide surface to provide, respectively, M-O-C and M-C bonded intermediates. These studies were carried out with a sample of 9.0 wt% Mo03/Si02, which Raman spectroscopy and x-ray diffraction showed to consist of fine (- 5nm) crystallites of M0O3 (23). 

Violent reactions with ammonium salts, chlorate salts, beryllium fluoride, boron diiodophosphide, carbon tetrachloride + methanol, 1,1,1-trichloroethane, 1,2-dibromoethane, halogens or interhalogens (e.g., fluorine, chlorine, bromine, iodine vapor, chlorine trifluoride, iodine heptafluoride), hydrogen iodide, metal oxides + heat (e.g., beryllium oxide, cadmium oxide, copper oxide, mercury oxide, molybdenum oxide, tin oxide, zinc oxide), nitrogen (when ignited), silicon dioxide powder + heat, polytetrafluoroethylene powder + heat. 

Gryzbowska et al. [106] compared the reaction products formed when pulses of allyl iodide or propene were passed over bismuth oxide or molybdenum oxide. A clear limitation of these experiments is that even the simplest bismuth molybdate catalysts contain neither bismuth oxide nor molybdenum oxide, but instead are made up of a binary oxide of bismuth and molybdenum, whose structure is different to that of bismuth oxide and molybdenum oxide. Gryzbowska et al. selected allyl iodide because of the very low bond dissociation enthalpy associated with the C-I bond, implying that a surface allyl species would readily form from this starting material. In addition, a lower reaction temperature was required for the reaction of allyl iodide than for propene reflecting the greater inherent reactivity of the former. 

Over bismuth oxide no acrolein was formed from propene and just small amounts from allyl iodide. Instead the major reaction product was the dimer hexadiene, formed from the dimerization of two allyl species. Over molybdenum oxide no reaction occurred with propene but copious amounts of acrolein formed from allyl iodide. These results are summarized in Table 5.12. 

These results led to the postulate that the bismuth component of bismuth molybdate catalysts is responsible for the abstraction of the first hydrogen from propene, but that this oxide is not capable of inserting oxygen into the reaction intermediate which forms. Instead any allyl species which form over this oxide from allyl iodide and less easily from propene, dimerize to hexadiene in the absence of a suitable source of oxygen. By contrast, allyl species do not form from propene over molybdenum oxide. However, when this oxide is exposed to a facile source of allyl species, namely allyl iodide, acrolein forms readily, consistent with the oxygen insertion and second hydrogen abstraction steps occurring over this component of the bismuth molybdate catalysts. 

Oxides of the type A O- (A = alkali metal) are known as tungsten oxide bronzes. These are readily prepared by the insertion of the alkali metal into WO3. The corresponding molybdenum bronzes are more difficult to prepare. High pressures and electrochemical methods are generally employed to synthesize some of them. A simple solid-state reaction between an alkali iodide and M0O3 or Moj j Wj 03 (under dry conditions) has been found to yield such molybdenum oxide bronzes [11]. The following reaction represents a simple means of making these bronzes ... 

Senapati H, Parthasarathy G, Lakshmikumar SK et al (1983) Effect of pressure on the fast-ion conduction in silver iodide-silver oxide-molybdenum oxide glasses. Phil Mag B 47 291-297... 

Dithiol is a less selective reagent than thiocyanate for molybdenum. Tungsten interferes most seriously but does not do so in the presence of tartaric acid or citric acid (see Section 17.34). Tin does not interfere if the absorbance is read at 680 nm. Strong oxidants oxidise the reagent iron(III) salts should be reduced with potassium iodide solution and the liberated iodine removed with thiosulphate. 

In the case of molten salts, the functional electrolytes are generally oxides or halides. As examples of the use of oxides, mention may be made of the electrowinning processes for aluminum, tantalum, molybdenum, tungsten, and some of the rare earth metals. The appropriate oxides, dissolved in halide melts, act as the sources of the respective metals intended to be deposited cathodically. Halides are used as functional electrolytes for almost all other metals. In principle, all halides can be used, but in practice only fluorides and chlorides are used. Bromides and iodides are thermally unstable and are relatively expensive. Fluorides are ideally suited because of their stability and low volatility, their drawbacks pertain to the difficulty in obtaining them in forms free from oxygenated ions, and to their poor solubility in water. It is a truism that aqueous solubility makes the post-electrolysis separation of the electrodeposit from the electrolyte easy because the electrolyte can be leached away. The drawback associated with fluorides due to their poor solubility can, to a large extent, be overcome by using double fluorides instead of simple fluorides. Chlorides are widely used in electrodeposition because they are readily available in a pure form and... 

Manganese trichloride oxide, 4141 Manganese trifluoride, 4335 Mercury(II) bromide, 0269 Mercury(I) fluoride, 4312 Mercury(II) iodide, 4602 Molybdenum hexafluoride, 4365 Molybdenum pentachloride, 4180 Neptunium hexafluoride, 4366 Osmium hexafluoride, 4370 Palladium tetrafluoride, 4347 Palladium trifluoride, 4341... 

Iodide ion-selective electrode The iodide electrode has broad application both in the direct determination of iodide ions present in various media as well as for the determination of iodide in various compounds. It is, for example, important in the determination of iodide in milk [44,64,218, 382, 442], This electrode responds to Hg ions [150, 306, 439] and can be used for the indirect determination of oxidizing agents that react with iodide, such as 10 [305], lOi [158], Pd(II) [117, 347,405] and for the determination of the overall oxidant content, for example in the atmosphere [393], It can also be used to monitor the iodide concentration formed during the reactions of iodide with hydrogen peroxide or perborate, catalyzed by molybdenum, tungsten or vanadium ions, permitting determination of traces of these metals [12,192,193, 194, 195]. The permeability of bilayer lipid membranes for iodide can be measured using an I"... 

In contrast to the unsuccessful early attempts to produce [W2(02CR)4], the heteronuclear compound [MoW(02CCMe3)4] was obtained by reacting a 3 1 mixture of W(CO)6 and vlo(CO)6 in refluxing dichlorobenzene.334 The heteronuclear complex was freed from Mo2(02CCMe3)4] by careful oxidation with I2. Structure analysis of MoW(02CCMe3)4]I-MeCN shows the expected idealized Dih symmetry with a short W—Mo separation of 2.194 A. The iodide ion is coordinated to the W atom and the MeCN molecule is coordinated to the molybdenum atom. 

Photocurrent voltage curves have been studied with molybdenum selenide crystals of different orientation and different pretreatment. Figure 5 represents results for three typical surfaces of n-type MoSe (JJ+). An electrode with a very smooth surface cleaved parallel to the van der Waals-plane shows a very low dark current in contact with the KI containing electrolyte since iodide cannot directly inject electrons into the conduction band and can only be oxidized by holes. At a bias positive from the flat band potential U where a depletion layer is formed a photocurrent can be observed as shown in this Figure. This photocurrent reaches a saturation at a potential about 300 mV more positive than when surface recombination becomes negligible. 

Tungsten and molybdenum bronzes, AxW03 and AxMo03 (As k, Rb, Cs) are generally prepared by reaction of the alkali metals with the host oxide. Electrochemical methods are also employed for these preparations. A novel reaction that has been employed to prepare bronzes which are otherwise difficult to obtain involves the reaction of oxide host with anhydrous alkali iodides [49] ... 

Hexacarbonylchromium(O) is readily attacked by chlorine giving CrCb, CO, and COCI2. Bromine and iodine do not attack Cr(CO)6 to any substantial extent at room temperature. The chromium tricarbonyl arene complexes, Cr(CO)3( -arene), are readily oxidized at room temperature by I2 to give Cris this is a conveitient preparative method for the anhydrous iodide. Although the oxidation of the tricarbonyl arene derivatives of chrontium with I2 does not show evidence of intermediate carbonyl complexes in oxidation states >0, the corresponding molybdenum(O) compounds give a series of carbonyl iodides of molybdenum(II), for example, the ionic [Mo(CO)3 ( ) -arene)]I. 

Other hazardous reactions may occur with carbon (e.g., soot, graphite, activated charcoal), dimethyl sulfoxide, ethylene oxide, chlorine, bromine vapor, hydrogen bromide, potassium iodide + magnesium bromide, chloride or iodide, maleic anhydride, mercury, copper(II) oxide, mercury(II) oxide, tin(IV) oxide, molybdenum(III) oxide, bismuth trioxide, phosphoms trichloride, sulfur dioxide, chromium trioxide. 

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