Molybdenum carbonyls

Selectivities to various isomers are more difficult to predict when metal oxides are used as catalysts. ZnO preferentially produced 79% 1-butene and several percent of i7j -2-butene [624-64-6] (75). CdO catalyst produced 55% 1-butene and 45% i7j -2-butene. It was also reported that while interconversion between 1-butene and i7j -2-butene was quite facile on CdO, cis—trans isomeri2ation was slow. This was attributed to the presence of a TT-aHyl anion intermediate (76). High i7j -2-butene selectivities were obtained with molybdenum carbonyl encapsulated in 2eohtes (77). On the other hand, deuteration using H1O2 catalyst produced predominantly the 1,4-addition product, trans-2-huX.en.e-d2 with no isotope scrambling (78). 

When heated to about 60°C, nickel carbonyl explodes. Eor both iron and nickel carbonyl, suitable fire extinguishers are water, foam, carbon dioxide, or dry chemical. Large amounts of iron pentacarbonyl also have been reported to ignite spontaneously (189). Solutions of molybdenum carbonyl have been reported to be capable of spontaneous detonation (190). The toxicity of industrial chemicals including metal carbonyls may be found in references 191-194. 

The MofVJ compounds [Mo(R2cffc)4]X can be prepared by oxidative addition of thiuram disulfide to molybdenum carbonyls or by mild oxidation of Mo(R2C fc)4. 

A structural study of a molybdenum carbonyl complex of phosphabenzene has shown that the phosphorus is a-bonded to the... 

In acyclic secondary -allylic alcohols, epoxidation by the vanadium system shows opposite stereospecificity to that of peracid and molybdenum carbonyl-mediated epoxidation (see Scheme 6)22 The predominance of the erythro isomer in the former process is rationalized22 in terms of the energetically more favorable transition state (6, cf. 5) and in this context the mechanism has analogy in the epoxidation behavior of medium-ring cyclic allylic alcohols.23... 

The presence of a 2-substitutent in 3-phenylazirines (17, R —H in Scheme 21) modifies the mode of reaction with molybdenum carbonyl.47 In contrast to pyrazine formation for (17, R =H see Section V,C,2), the alkenyl azirine (18, Scheme 22) is transformed in excellent yield into 2-phenyl-5-carboxy-methylpyrrole. This product probably arises by intramolecular cyclization within an intermediate dienylnitrene intermediate, and related reactions have been devised to synthesize isoxazoles (see Section IV,E,2) and pyrazoles (see Section IV,D,1).47 The molybdenum carbonyl-promoted formation of 2,5-disubstituted pyrroles47 has analogy in uncatalyzed thermal, but not photochemical decomposition of 3-phenyl-2//-azirine 2-acrylate.49... 

Pyrroles among other products are also formed from diiron enneacarbonyl or molybdenum carbonyl-induced decomposition of the Z-ketovinylazirine... 

Complexes of diazadiphosphacyclooctanes with molybdenum carbonyl have been obtained [Eq. (146)] (80TL1409, 80TL1845 81TL1105). In this case heterocycles play the role of a chelate. 

In a similar manner, Jt-allyl complexes of manganese, iron, and molybdenum carbonyls have been obtained from the corresponding metal carbonyl halides [5], In the case of the reaction of dicarbonyl(r 5-cyclopentadienyl)molybdenum bromide with allyl bromide, the c-allyl derivative is obtained in 75% yield in dichloromethane, but the Jt-allyl complex is the sole product (95%), when the reaction is conducted in a watenbenzene two-phase system. Similar solvent effects are observed in the corresponding reaction of the iron compound. As with the cobalt tetracarbonyl anion, it is... 

Selected examples of the conversion of benzyl chlorides into arylacetic acids and arylpyruvic acids using molybdenum carbonyl complexes ... 

Analogous carbonylation reactions using nickel and iron carbonyl based systems also produce alkanecarboxylic acids [11, 13, 14]. The mechanism of the conversion of benzyl halides into arylacetic acids using iron pentacarbonyl is not as well defined as it is for reactions promoted by nickel or molybdenum carbonyl complexes. Iron... 

Initially a catalyst was obtained by in situ mixing, using a method that was relatively satisfactory for alkenes. Heating molybdenum carbonyl with resorcinol or chlorophenol at high temperatures (110-160 °C) gave a few... 

Recently, a polymer-bound molybdenum carbonyl has been reported to be highly active for the epoxidation of various alkanes in the Hquid phase [38]. 

MOLYBDENUM CARBONYL-CATALYZED ALKYNOL CYCLOISOMERIZATION PREPARATION OF 2-PHENYL-2,3-DIHYDROFURAN (Furan, 2,3-dihydro-2-phenyl-)... 

Molybdenum hexacarbonyl Molybdenum carbonyl (8) Molybdenum carbonyl, (OC-6-11) (9) (13939-06-5)... 

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. 

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