Nitrogen monoxide tungsten

Differential scanning calorimetry has been used to measure89,90 the enthalpy of reaction for the displacement of a nitrogen donor ligand, L, from tungsten complexes [W(CO)6 L ] by carbon monoxide under isobaric conditions. The reaction is described by the equation... 

In addition to the successful reductive carbonylation systems utilizing the rhodium or palladium catalysts described above, a nonnoble metal system has been developed (27). When methyl acetate or dimethyl ether was treated with carbon monoxide and hydrogen in the presence of an iodide compound, a trivalent phosphorous or nitrogen promoter, and a nickel-molybdenum or nickel-tungsten catalyst, EDA was formed. The catalytst is generated in the reaction mixture by addition of appropriate metallic complexes, such as 5 1 combination of bis(triphenylphosphine)-nickel dicarbonyl to molybdenum carbonyl. These same catalyst systems have proven effective as a rhodium replacement in methyl acetate carbonylations (28). Though the rates of EDA formation are slower than with the noble metals, the major advantage is the relative inexpense of catalytic materials. Chemistry virtually identical to noble-metal catalysis probably occurs since reaction profiles are very similar by products include acetic anhydride, acetaldehyde, and methane, with ethanol in trace quantities. 

According to our work with nitrogen bases, which was done in Heidelberg and in Stuttgart (1933/34), it was shown that pyridine, o-phenanthroline, and 1,2-ethylenediamine react in a different manner with the hexacarbonyls of chromium, molybdenum, and tungsten with, in each case, substitution of the carbon monoxide ligands (VII, 27). 

A preliminary study of other reactions revealed a very great variety in the possibilities of reaction (see especially g i, p. 2273). Molybdenum and carbon monoxide reacted just like tungsten and nitrogen. Many decompositions take place at the surface of heated filaments e.g. tungsten will decompose ammonia, carbon dioxide, and cyanogen. Sometimes the... 

Chemisorption-induced metal atom reorganization at low temperatures had been discovered in the 1960s by field ion microscopy in chemisorption studies of nitrogen and carbon monoxide on a tungsten single-crystal tip (55-58). Likewise, surfece reconstruction was concluded from research of chemisorption on metal and bimetal films (59-61). This surface reconstruction was observed particularly on open crystal faces the more closely packed faces are often corroded from their edges with the former faces. Surface reconstruction is of particular relevance to alloy surfaces, where it leads to chemisorption-induced segregation of one alloy component to the... 

NITROGEN OXIDE (10024-97-2) May form explosive mixture with flammable and reactive gases, including anhydrous ammonia, carbon monoxide, chlorine trilluoride, hydrogen, hydrogen sulfide, nitryl fluoride, phosphine. Nonflammable but supports combustion as temperature increases above 572°F/300°C, it becomes both a strong oxidizer and self-reactive. Pyrophoric at elevated temperatures. Reacts, possibly violently, with aluminum, ammonia, boron, hydrazine, lithium hydride, sodium, tungsten carbide. 

In conclusion, by means of the foregoing analysis the heterogeneous character of chemisorption of nitrogen by a clean tungsten surface at room temperature is established. While all crystal surfaces accessible for examination appear to chemisorb nitrogen, some surfaces react relatively slowly. Surfaces of the latter type include the 100 planes that are expected to be atomically smooth. Thus, low reactivity may be correlated with surface smoothness. Apparently this factor is significant for the chemisorption of oxygen and carbon monoxide as well. 

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