Molybdenum compounds, general properties

These complexes are generally prepared by methods similar to those employed for the dinitrosyl compounds, treatment of a low-valent molybdenum compound with NO or a nitrosyl derivative being the principal method. Compounds and major physical properties are collected in Table 3. 

General Properties of Compounds of Cobalt—Cobalt and the Halogens—Oxy-Halogon Derivatives—Cobalt and Oxygen—Cobalt and Sulphur—The Alums—Cobalt and Selenium, Tellurium, Chromium, and Molybdenum—... 

General Properties of Molybdenum Compounds—Molybdenum and Hydi-ogcn— Halogen and Oxyhalogen Compounds—Oxides and Hydroxides—Molybdio Acid, Molybdates, and Polymolybdates—Permolybdio Acid and Permolyb-dates—Compounds with Sulphur, Selenium, and Chromium. 

Compounds containing such metals as copper, barium, lead, molybdenum, and nickel generally are not used in processing solutions. However, trace quantities of certain metal dopants occasionally are used to impart desired soHd-state and photographic properties to emulsion grains. Because of its... 

When molybdenum disulphide is added to a grease, the effect on the flow properties depends critically on the concentration of molybdenum disulphide. Where the quantity added is high enough to cause a major change in the flow properties, the result is a product which no longer behaves as a grease, but behaves like a paste. Such materials are generally used as anti-seize compounds rather than lubricants, and they will be described in Section 13.4. 

Trivalent uranium ion reduces water to hydrogen. Hence, stable aqueous solutions of trivalent uranium compounds cannot be prepared. Compounds of tetravalent uranium are generally similar to those of zirconium or thorium, except that some uranium compounds can be oxidized to the hexavalent form. Compounds of pentavalent uranium are of little importance because they disproportionate readily into tetravalent and hexavalent forms. The properties of hexavalent uranium are generally similar to those of hexavalent molybdenum or tungsten. In aqueous solution hexavalent uranium forms the uranyl ion UO2 ... 

Nitrogenase is another big target of cluster synthesis. The X-ray elucidation of the active center of the Fe-Mo cofactor and P-cluster (5) has accelerated the efforts to find rational preparative methods of trinuclear or cubane-type clusters containing molybdenum (6-9). The raft cores in these cluster complexes are one of the general structural units also in solid-state compounds, and the mutual relationships are very important. A number of review articles are now available on the syntheses, structures, and other properties of metal chalcogenide cluster compounds (6, 7,10-24). 

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