Aluminum zirconium

Treatment of alkylidene-bridged zirconium—aluminum species with HMPA activates the C—A1 bond of the alkylidene unit, making it susceptible to electrophilic attack [146]. Ligand-based activation of the C—A1 bond can also be used to convert alkylidene-bridged zirconium-aluminum reagents to other bimetallic species. Thus, treatment of 3 with HMPA followed by addition of a weakly electrophilic metal salt can give rise to a new heterome-tallic species. Slow addition of a solution of R3SnCl in toluene to a solution of 3 and 1... 

Besides compound 8, a further remarkable zirconium-aluminum compound (9) can be isolated, which is derived from tetra(cyclopentadienyl)-zirconium. The tris(cyclopentadienyl)zirconium(IV) is linked with the trialkylaluminum by a hydrogen atom (see Fig. 18). 

Control of Molecular Weight by Regulation of Temperature in the Polymerization of Ethylene with Tri(cyclopentadienyl)zirconium-Aluminum Compounds... 

Other mixed gm-dimetalhc compounds containing zinc and either zirconium, aluminum, or titanium have been successfully prepared from alkynylzinc halide compounds via hydrozirconation by H(Cl)ZrCp2 (the Schwartz s reagent) or carbometalation by a combination of Me3AECp2TiCl2 (Scheme 15). 

Zirconium-aluminum analogs of the Tebbe reagent have been reported to react with carbonyl compounds slowly, in low yield or not at all. However, zirconium aUcylidenes which are stabilized by a phosphorus rather than an aluminum ligand do transfer their alkylidene moiety to carbonyl. These results provide some of the few examples of long chain alkylidene transfer to ca nyl from an organo-metallic reagent (equation 31). 

FIGURE 8.6 The relative concentration of different zirconium, aluminum, magnesium, and yttrium hydroxide species as a function of pH at 25°C in 1.0 mol/dm aqueous solutions. (From Bergstrom, L., in Surface arid Colloid Chemistry in Advanced Ceramics Processing, R.J. Pugh and L. Bergstrom, Eds., Marcel Dekker, New York, 1994, 100-101. With permission.)... 

Titanium was first produced in large quantities in 1910 by Hunter, who reacted titanium tetrachloride with sodium. Compounds of the elements zirconium, aluminum, beryllium, magnesium, thorium, and boron can be reduced to the metal with sodium. 

Certain other alloys such as zirconium-aluminum and zinc-aluminum do not function. 

A comparative study of the role of zirconium, aluminum, lanthanum and neodymium as dopants for dehydrogenation catalysts was carried out by Ramos at al. [89]. Regarding activity, they found that lanthanum was the most efficient dopant, making hematite three times more active than the pure oxide. However, lanthanum decreased the selectivity from 92 % (pme oxide) to 88 % (doped hematite). 

A similar cyclopropanation to the Kulinkovich reaction was achieved by the use of zirconium aluminum complexes in the presence of magnesium (Scheme 1.213) [297],... 

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