Tungsten methoxide

Tetrakis(ethylthio)uranium, 3096 Titanium butoxide, 3730 Titanium(III) methoxide, 1317 Titanium tetraisopropoxide, 3579 Tungsten hexamethoxide, 2604 Zinc ethoxide, 1704... 

In 1979, Rudler ef al. reported another example of the presence of a vinylidene complex during the reaction of pentacarbonyl[methoxy(methyl)carbene] tungsten 5 with MeLi followed by acidification with TFA [4]. It was proposed that the vinylidene complex 7 was generated by deprotonation of the a-proton of the carbene complex followed by elimination of methoxide and reaction with the dimethylcarbene complex 8, the addition-elimination product of MeLi with the starting carbene complex, to give the dinuclear complex 6 (Scheme 5.2). 

Tetrakis(ethylthio)uranium, 3090 Titanium butoxide, 3724 Titanium tetraisopropoxide, 3573 Titanium(III) methoxide, 1313 Tungsten hexamethoxide, 2600 Zinc ethoxide, 1698... 

Studies on the base-catalyzed substitution of halide for methoxide in complexes rans-[M(NH)X(dppe)2]+ (M = Mo or W) have shown (for X = F or Cl) that the imido group in the tungsten complexes is some 1000-fold less acidic than in the molybdenum ones (188). 

Tungsten derivatives, both CpW(CO)(RC=CH)(R ) and CpW(CO)-(RC=CH)[C(0)R ], consistently exhibit 13-C signals between 185 and 200 ppm with single bond xJCh values of 190-205 Hz for alkyl derivatives and 205-215 Hz for acyl derivatives (69). Incorporation of methoxide in place of the alkyl or acyl ligand shifts the alkyne carbons slightly upheld to 169 and 176 ppm (75), presumably reflecting competition between alkyne... 

Addition of methoxide to the cationic phosphonioalkylidyne complexes [Tp W(=CPPh3)(CO)2] likewise allows the isolation of the thermal- and light-sensitive methoxycarbyne complex Tp W(=COMe)(CO)2 in 48% yield. It is necessary to quench the reaction with excess Mel to prevent subsequent dealkylative conversion to the tricarbonyl anion P p W(CO)3] . The electron-rich methoxy group results in vco frequencies at 1958 and 1862 cm which are towards the low end of the range observed for neutral Tp dicarbonyl tungsten complexes. ... 

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