Organomolybdenum complexes

Keywords Organomolybdenum complexes Oxidation catalysis Heterogenisation... 

Immobilized complexes anchored to the surface of oxide supports may serve as active metathesis catalysts. In fact, Mo(CO)6 on alumina was reported in the first paper on metathesis by Banks and Bailey.1 Molybdenum and tungsten hexacarbo-nyls and alkylmolybdenum and alkyltungsten complexes have been studied most.6,24,26 Anchored organomolybdenum complexes are particularly effective catalysts, even at temperatures below 0°C however, they quickly lose activity.41-43... 

An exotic organomolybdenum complex derivative of terthiophene 44 was found to be electropolymerizable to give a thin electrochromic film with two Mo-centered oxidations superimposed upon the thiophene oxidation. The film switched between purple (undoped) and transparent blue (doped). These colors are quite different from... 

When the C-H activation process is inefficient or difficult to carry out, one can often resort to alternative methods such as transmetallation reactions, as in the synthesis of the interesting cycloruthenated complex 13. The corresponding C-H activation process for 2 gives only a 38% yield." A similar method was employed for the synthetically useful cyclopalladated ketone derivative 15 and for the organomolybdenum complex 17.Oxidative additions of suitably substituted iodo derivatives on Pd(0) were employed to synthesize the primary 8-napthylamine complex 19 and the complexes 21 with a variety of substitution patterns on the thioether group. 

METHYLENATION Alkyidimesitylboranes. p,-Chlorobis(cyclopentadienyl)(dimethyl-aluminum)-p.-methylene-titanium. Methylene bromide-Zinc-Titanium(IV) chloride. Organomolybdenum reagents. Titanocene methylene-Zn halide complex. N,N,P-Tri-methyl-P-phenylphosphinothioic amide. Trimethylstannylmethyllithium. 

Complexes of Mo and V as naphthenates [126], carbonyls [169], and acetyla-cetonates [170] have been studied extensively [101,171-173] (Table 1.6). Mo and V are the most active metals for epoxidation with hydroperoxides, and are the basis for one of the industrial production methods of PO. An organomolybdenum compound, T -(C5Bz5)MoO2C1 has been reported with high activity for epoxidation of ds-cyclooctene with TBHP [174]. The authors report a TOF of 0.33 s at 55 °C, but this may have been an initial rate. Using quantities from the paper, an average TOF of 6.9 x 10 s in 4 h is calculated. The catalyst has similar activity for styrene epoxidation, but lower for 1-octene. 

The most widely used types of radical scavengers are phenolic and aminic antioxidants. The use of organometallic complexes of transition metals as antioxidants is becoming more prevalent, especially in engine oils organomolybdenum compounds are of particular importance. 

Scheme 2.7 shows the synthesis of organomolybdenum polymers containing metal-metal bonds.83 Polymer 36 was prepared via reaction of trans-Mo(CO)3Cl containing t)5-Mo complexes with MeMgCl. They displayed poor solubilities. 

The published work on chromium is concerned mainly with the gas chromatography of arene tricarbonyl chromium complexes. Little has been published on the gas chromatography of organomolybdenum compounds and no work has been found on the compounds of tungsten and uranium. 

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