Molybdenum, dicarbonyl

Allyl(dicarbonyl)molybdenum complexes 5 are also prepared from 4 via the methyl derivative... 

Lithium benzenetellurolate or bromomagnesium benzcnetellurolate and cycloheptatrienyl-(dicarbonyl)molybdenum bromide produced the benzenetellurolato-bridged dinuclear molybdenum complex, dicarbonylbis[l-7-r -cycloheptatrienyl -bis[p-benzeneteUurolato] di-molybdenum( II)1. 

While 2,2 -bipyridine or phenanthroline adducts are likely to contain an approximately planar, five-membered -M-N-C-C-N moiety, upon coordination of a RR 2C(pz)2 a six-membered cycle is formed for which a boat conformation is predicted. Nevertheless, both the internal and external angles of the formally related M-(N-N)2-E moieties (where E is not carbon), are known to be able to undergo wide variations. Indeed, X-ray studies carried out on several / ,-pyrazolato-/V,/V -derivatives showed that the six-membered ring is not always in the boat conformation. This may undergo a severe folding as in bis(3,5-dimethylpyrazolyl)borato-7V,/V ](//3-cyclohepLatrienyl) (dicarbonyl)molybdenum,195 or may even approximate a chair, or at least, a distorted chair as in dimeric bis(cyclopentadienyltitanium)(//-pyrazolato-/V,7V ) (Scheme 10a).196... 

CH3CN)3Mn(CO)3]PP6 to give the half sandwich complex (15) whereas an j -ray structure of the product shows that the neutral ligand reacts with hexacarbonyImolybdenum (0) to form n-allyl(l-tert--butyl-2-methyl-n-l,2-azaborolinyl)dicarbonyl molybdenum (0). 

Cl8Hi5B3CI3N3, B-Trichloro-N-triphenylborazine, 43B, 819 Cl8H20B2C0N12, Bis(hydrotris(1-pyrazolyl)borato)cobalt(II), 35B, 434 Cl8H24BM0N6O2 f (Diethylbispyrazolylborato)(pyrazolato)(rj -allyl)(dicarbonyl )molybdenum, 39B, 479... 

CisHi3FeN06, Tricarbonyl-(methyl a-acetamidocinnamate)iron, 46B, 841 Cl 5H13M0NO2, (rj -N-Phenyliminoethyl) (T -cyclopentadienyl)dicarbonyl-molybdenum, 44B, 745... 

C21H2 sBMoNi,02, (Diethyl-1 -pyrazolylborato)-(r -2-phenylallyl) (dicarbonyl) molybdenum, 40B, 731... 

C211H2 3BMoNi,02 f (Diphenyldipyrazolylborato) (2-me thy la llyl) dicarbonyl-molybdenum, 41B, 883... 

Most preparations of the intermediate racemic 3-allyl(dicarhonyl)cyclopentadieny molybdenum complexes7 2 start from sodium or potassium tricarbonyl(cyclopentadienyl)molybdate8 9 10 (4) for a simple preparation see ref 11, p 493. The allylation of 4 hy homoallylic halides, such as 4-hromo-l-butene, is accompanied by rearrangement and decarhonylationI2. (Z)-if-2-butenyl(dicarbonyl)cyclopentadienylmolybdenum (5), like other comparable complexes, exists as a mixture of endo/exo- conformers, which interconvert rapidly at room temperature12. 

A single example of a rr-alkyl molybdenum complex was serendipitously prepared from a solution of the very light-sensitive dicarbonyl complex Mo(TPP)(CO)2. 

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... 

Experimental Procedure 3.1.4. Preparation of a Molybdenum Vinylidene Complex from a Carbyne Complex Tetrabutylanunoniuih Cyano(ethoxycarbonyl) vinylidene (dicarbonyl) hydro-tris(3,5-dimethyl-1 -pyrazblyl)borato molybdenum [526] [37] pp 151 and 188... 

The retrosynthetic analysis of the 2-oxygenated carbazole alkaloids, 2-methoxy-3-methylcarbazole (37), O-methylmukonal (glycosinine) (38), 2-hydroxy-3-methylcar-bazole (52), and mukonal (53) based on the molybdenum-mediated approach led to the molybdenum-complexed cation (663) and 3-methoxy-4-methylaniline (655) as precursors (Scheme 5.51). The cationic molybdenum complex, dicarbonyl (ri -cyclohexadiene)(r -cyclopentadienyl)molybdenum hexafluorophosphate (663), required for the electrophilic substitution, was easily prepared quantitatively through known literature procedures (586,587). 

We reported the first total synthesis of l,T-bis(2-hydroxy-3-methylcarbazole) (213) using our molybdenum-mediated construction of the carbazole framework (560). The required monomer, 2-hydroxy-3-methylcarbazole (52), was obtained in three steps, and 22% overall yield, starting from dicarbonyl(ri -cyclohexa-l,3-diene)(ri -cyclopentadienyl)molybdenum hexafluorophosphate (663) and 3-meth-oxy-4-methylaniline (655) (560) (see Scheme 5.52). Finally, oxidative coupling of the monomer 52 using p-chloranil afforded l,T-bis(2-hydroxy-3-methylcarbazole) (213) in 38% yield (560) (Scheme 5.167). 

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. 

Alkylations of dicarbonyl( 75-cyclopentadienyl)(l-3>7-5-oxocyclohexenyl)molybdenum (28) proceed with high diastereoselectivity to yield mainly the mono- or diaikylated toco-products 29 depending on the molar ratio of ketone/alkylating agent used105. 

O4AICIN2C34H54, Aluminum, dimethanol-1,2-bis(2-hydroxy-3,5-bis(tert-butyl)benzylide-neimino)ethane-, chloride, 34 17 O4BM0N6C16H17, Molybdenum(II), dicarbonyl hydridotris( 1 -py razolyl)borato 7)-(1,2,3)-(+)-( 1 R,2R)-1 -(methoxycarbonyl)-2-propen-l-yl -, 34 105 O4B2C12H4, Diborane(4), catechol derivative, 34 4... 

Dicarbonyl(ti5-cyclopentadienyl)hydrido(triphenylphosphine) molybdenum and -tungsten... 

Dicarbonyl(T)5-cyclopentadienyl)(tetrafluoroborato)(triphenylphosphine)-molybdenum and -tungsten4... 

BF4MoOPCwH](), Molybdenum(l +), car-bonyl-(-n5-cyclopentadienyl)-(diphenylacetylene)-(triphenylphosphine)-tetrafluoroborate(l -), 26 104 BF4MoO2PC25H20, Molybdenum, dicarbonyl-(T) -cyclopentadienyl)-[tetrafluoroborato(l -)] (triphenylphosphine)-, 26 98 BF4MoOjCbH5, Molybdenum, tricarbonyl-(ry -cyclopentadienyl) [tetrafluorobor-ato (1-)]-, 26 96... 

HMoOjPC Ha, Molybdenum, dicarbonyl-(V-cyclopentadienyl)hydrido(tri-phenylphosphine)-, 26 98... 

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