4-methyl tungsten complex

CsHuN, Ethanamine, A-ethyl-A-methyl-tungsten complex, 26 40, 42 C6HF5, Benzene, pentafluoro-gold complexes, 26 86-90 C H4I2, Benzene, 1,2-diido-iridium complex, 26 125 CJT, Phenyl platinum complex, 26 136 C,H,N, Pyridine osmium complex, 26 291 OHtS, Benzenethiol osmium complex, 26 304 QH7P, Phosphine, phenyl-cobalt-iron complex, 26 353 QH 1-Butyne, 3,3-dimethyl-mercury-molybdenum-ruthenium complex, 26 329-335 C6H 4P, Phosphine, triethyl-platinum complex, 26 126 platinum complexes, 26 135-140 CsHisPO, Triethyl phosphite iron complex, 26 61... 

CsHiuOj, Propanoic acid, 2,2-dimethyl-, tungsten complex, 26 223 C,H 2, Propane, 2,2-dimcthyl-, magnesium and tungsten complexes, 26 46, 47, 50 C,Hi,N, Ethanamine, IV-ethyl-yV-methyl-, tungsten complex, 26 40, 42 QHF5, Benzene, pentafluoro-, gold complexes, 26 86-90... 

Another example of a [4S+1C] cycloaddition process is found in the reaction of alkenylcarbene complexes and lithium enolates derived from alkynyl methyl ketones. In Sect. 2.6.4.9 it was described how, in general, lithium enolates react with alkenylcarbene complexes to produce [3C+2S] cycloadducts. However, when the reaction is performed using lithium enolates derived from alkynyl methyl ketones and the temperature is raised to 65 °C, a new formal [4s+lcj cy-clopentenone derivative is formed [79] (Scheme 38). The mechanism proposed for this transformation supposes the formation of the [3C+2S] cycloadducts as depicted in Scheme 32 (see Sect. 2.6.4.9). This intermediate evolves through a retro-aldol-type reaction followed by an intramolecular Michael addition of the allyllithium to the ynone moiety to give the final cyclopentenone derivatives after hydrolysis. The role of the pentacarbonyltungsten fragment seems to be crucial for the outcome of this reaction, as experiments carried out with isolated intermediates in the absence of tungsten complexes do not afford the [4S+1C] cycloadducts (Scheme 38). 

A family of molybdenum and tungsten complexes with the formula [M(Cp)(C0)2(PR3)(0=CEt2)]BAr4 [Ar = 3,5-6isftrifluoro-methyl)phenyl] are known to operate through this mechanism. In most of the cases, the rate-limiting step was the ketone displacement for H2 in order to form the active dihydride (55,56). An... 

CjHjS, Thiophene, tetrahydro-gold complexes, 26 85-87 C4H,NO, 2-Propenamide, 2-methyl-nickel complex, 26 205 C4H1()02, Ethane, 1,2-dimethoxy-solvates of chromium, molybdenum, and tungsten carbonyl cyclopentadienyl complexes, 6 343 tungsten complex, 26 50 ytterbium complex, 26 22 C4H i02.NaC5H5, Ethane, 1,2-dimethoxy-compd. with cyclopentadienylsodium, 26 341... 

C4H 2OSi, Silane, methoxytrimethyl-, 26 44 CH4N, Propane, 2-isocyant-2-methyl-ruthenium complex, 26 275 C][l,4]-dithiin-2-thione, 26 389 CHfc, 1,3-Cyclopentadiene cobalt complex, 26 191-197, 309 chromium, molybdenum, and tungsten complexes, 26 343 iron complex, 26 232-241 mercury-molybdenum-ruthenium complex, 26 333... 

NO, Nitrosyls, molybdenum and tungsten, 26 132, 133 NOC, Cyanate tungsten complex, 26 42 NOC4H7, 3-Butenamide nickel complex, 26 206 NOC4H , 2-Propenamide, 2-methyl-nickel complex, 26 205 NOC H, Benzoyl isocyanide chromium complex, 26 32, 34, 35 N04ReC16H, Perrhenate, tetrabutylam-monium, 26 391... 

OiCsHm, Propanoic acid, 2,2-dimethyl-tungsten complex, 26 223 02C Hh, Methyl benzoate chromium complex, 26 32 02CuiH (, 2,3-Naphthalenediol in prepn. of cu-tetraamminedihaloruthe-nium(III) complexes, 26 66, 67... 

A number of reactions between M2(OR)6 compounds and alkynes have been found to give alkylidyne compounds by a metathesis of the M=M and C=C bonds (see Sections 15.3.6.4) and evidence has been presented275 for an equilibrium between a ditungstatetrahedrane and a methyl-idyne-tungsten complex supported by BulO ligands (equation 72). 

The monoanionic tungsten complex W[S2C2Ph(p-MeOPh)]3 has been reported to catalyze formation of hydrogen from water, using free radicals derived from methyl viologen as the source of electrons (112). The catalytic cycle has been proposed to involve sequential electron and proton transfer. 

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