Tungsten carbonyl, decomposition

Group 6 metal (chromium, molybdenum, tungsten) carbonyls trapped in zeolites have been found to undergo partial thermal decomposition to produce M(CO)3 species which react with phosphines, polyolefins, and arenes to form the expected complexes, e.g. ( / -C6H6)Cr(CO)3 [210]. 

Tungsten carbide from the decomposition of tungsten carbonyl (W(CO)5 at 350-400 C although carbon tends to remain incorporated in the structure... 

Transition metal complexes which react with diazoalkanes to yield carbene complexes can be catalysts for diazodecomposition (see Section 4.1). In addition to the requirements mentioned above (free coordination site, electrophi-licity), transition metal complexes can catalyze the decomposition of diazoalkanes if the corresponding carbene complexes are capable of transferring the carbene fragment to a substrate with simultaneous regeneration of the original complex. Metal carbonyls of chromium, iron, cobalt, nickel, molybdenum, and tungsten all catalyze the decomposition of diazomethane [493]. Other related catalysts are (CO)5W=C(OMe)Ph [509], [Cp(CO)2Fe(THF)][BF4] [510,511], and (CO)5Cr(COD) [52,512]. These compounds are sufficiently electrophilic to catalyze the decomposition of weakly nucleophilic, acceptor-substituted diazoalkanes. 

The mass spectra of bimetallic carbonyl metal compounds with cyclic arsine ligands have been discussed (Table 10). Molecular ion peaks are present for the pentamethyl-cyclopentaarsine containing complexes of chromium and tungsten, (AsMe)5[M(CO)]2 (186,188). Their decomposition includes CO and/or M(CO)5 loss giving rise to the ions (AsMe)sM2(CO) + (n = 0-9), (AsMe)sM(CO)/ (n = 0-5), M As Me-" and MAs Me+ (m = 2-4), MjAs Me, M AsMe -" (m = 2-4), MAs (w = 2-5), MAsjCH and AsMOj The latter is the most abundant in the mass spectra . ... 

Use Tungsten coatings on base metals by deposition and decomposition of the carbonyl. 

An alternative method is the decomposition of vapours of volatile metal compounds on the base metal surface, e.g., tungsten is coated by the decomposition of its hexachloride and nickel by decomposition of nickel carbonyl. 

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