Molybdenum ammonium cation

Electrochemical recognition, 39 80 anions, macrocyclic and acyclic polycobalti-cinium ligand systems, 39 134-140 cations, 39 81-133 ammonium cation, 39 128-133 crown ether and bis crow ether ligands containing bipyridyl transition metal recognition sites, 39 111 crown ether dithiocarbamate and dithi-olene complexes, 39 123-124 di-h-cyclopentadienyl-molybdenum(IV) and -tungsten(IV) crown ether complexes, 39 107-108... 

P.J. Zapf, R.C. Haushalter, and J. Zubieta. Crystal engineering of inorganic/organic composite solids the structure-directing role of aromatic ammonium cations in the synthesis of the step -layered molybdenum oxide phase [4,4 -H2bpy][Mo7022] H20, Chem. Commun., 321 (1997)... 

The parent oxacalix[3]arenes show little ability to bind alkali metals, however, a range of quaternary ammonium cations are attracted to the symmetric cavity [4]. Deprotonation of the phenol moieties allows them to bind to transition metals (scandium, titanium, vanadium, rhodium, molybdenum, gold etc.) [5-7], lanthanides (lutetium, yttrium and lanthanum) [8,9] and actinides (uranium, as uranyl)... 

For example, if one of the hexacarbonyls is heated with an ionic halide in an ethereal solvent, salts of the [M(CO)5X] anions are formed (69, 70, 71). Useful in these reactions are iV-methylpyridinium halides, because of their relatively high solubility in organic solvents. Tetraalkylammonium salts may also be used, but with somewhat less satisfactory results (70, 71). Even the alkali metal halides form [M(CO)5X] ions when heated with the metal hexacarbonyls under appropriate conditions (70, 71). The yields are much poorer, however, due to the lower solubility of the alkali metal halides in organic solvents. In addition the products with alkali metal cations appear to be much less stable than those with the quaternary ammonium cations (70, 71). The halide ions may be chloride, bromide, and iodide, especially the latter. Diglyme (70, 71), dioxane (69), and tetrahydrofuran (122) have been used as solvents. The lowest boiling of these, tetrahydrofuran (b.p. 65 C), is probably only appropriate for reactions involving the especially reactive molybdenum hexacarbonyl, but this has not been definitively demonstrated for this particular reaction. 

Molybdenum/zeolite catalysts prepared by impregnating zeolites with ammonium hepiamolybdate solution generally give rise to poor dispersion of molybdenum [2]. In contrast, ion exchange would be an ideal method for loading active metal species onto supports. Few cationic forms are available as simple salts of molybdenum of high oxidation... 

A number of transition metals can be determined conveniently if their cations undergo a definite change of oxidation state see Oxidation Number) on titration with a standard solution of potassium permanganate, potassium dichromate, cerium(IV) sulfate, or ammonium hexanitratocerate(IV). Several visual indicators have been proposed, including diphenylamine and its derivatives, xylene cyanole FF, and especially A-phenylanthranilic acid and tris(l,10-phenanthroline)iron(II) sulfate ( ferroin ). Solutions of have been used in the determination of iron, copper, titanium, vanadium, molybdenum, tungsten, mercury, gold, silver, and bismuth, and standard solutions of and Sn F U, and and Mo have also... 

Phosphate concentration was measured by the molybdenum blue absorptiometry, and magnesium and ammonium ions were measured by cation chromatography. Properties of crystals were analyzed by Xray analysis and SEM photographs. 

Metal oxide polyanion / cationic surfactant system tungstate and molybdate were used as polyanionic compounds and combined with quatenary ammonium surfactants. The polyanions of tungsten and molybdenum are the most thoroughly investigated polyanion forming compounds. They are formed over a wide pH range from pH 1-10 with different compositions. 

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