Tungsten compounds oxidation reactions

SAFETY PROFILE Chronic inhalation causes lung damage in humans. Ignites at 600°C in nitrogen oxide atmospheres. Violent reaction with F2, CIF3, NOx, IF5, Pb02, NO2, N2O. See also TUNGSTEN COMPOUNDS. 

For large-scale preparations of the tetrachloride oxides, the reaction of the metal trioxide with sulfinyl chloride is most convenient. The procedure outlined below is similar to that of Col ten and co-workers,7 but gives details for obtaining the compounds, particularly tungsten tetrachloride oxide, in excess of 50-g quantities. The reactions may be scaled up or down several fold without deleterious effect. 

The chemical reduction of the higher Mo and W halides provides good yields of the octahedral clusters, but the mechanism is obscure. By contrast, chemical oxidation of zero-valent Mo and W leads to the bromo and iodo cluster species in poor yields but provides considerable insight into the formation of these cluster compounds. The reaction of the hexacarbonyls Mo(CO)6 or W(CO)6 with I2 at moderately low temperatures produces a mixture of metal halide phases (25, 16). In the reaction W(CO)6 with I2, lower nuclearity clusters have been isolated as reaction intermediates that lead to W6 species. The tri-, tetra-, and pentanuclear tungsten iodide species are obtained from W(CO)6 and I2 by varying reaction times and temperatures, and the... 

Other examples which strongly support the existence of a metal-metal double bond are furnished by the dinuclear alkoxo-bridged dimers (10). Several synthetic procedures have been reported for the preparation of these compounds. They include the oxidation of quadruply bonded tungsten compounds in alcoholic HCl solutions, the oxidation of [W2Cl9] in alcohols, the electrolytic reduction of alcoholic solutions of WCle and the alcoholysis of WCU. Other alkoxy derivatives can be prepared by a simple alcohol exchange reaction."... 

---