Zirconium compounds aluminum complexes

Concomitant with continued olefin insertion into the metal-carbon bond of the titanium-aluminum complex, alkyl exchange and hydrogen-transfer reactions are observed. Whereas the normal reduction mechanism for transition-metal-organic complexes is initiated by release of olefins with formation of hydride followed by hydride transfer (184, 185) to an alkyl group, in the case of some titanium and zirconium compounds a reverse reaction takes place. By the release of ethane, a dimetalloalkane is formed. In a second step, ethylene from the dimetalloalkane is evolved, and two reduced metal atoms remain (119). 

Hydrozirconation of alkenes. This organic metallic reagent reacts with olefins at 25-40° to form alkylzirconium complexes of the type (C5115)2 Zn(R)Cl, in which the transition metal moiety is attached to the least hindered position of the olefin. For example, when a suspension of (1) in benzene is shaken with 1-octene or either cis- or tran -4-octene, (2) is formed in quantitative yield. Thus internally metalated zirconium compounds undergo rearrangement much more rapidly than organoboron or aluminum analogs. Other examples of hydrozircon-ation are formulated. Very hindered olefins e.g., tetramethylethylene) fail to react at 40°. 

The chelate compounds, produced as shown in (2), are not decomposed at once by even (1 1) sulfuric acid and therefore a sensitive test for aluminum has been developed on this basis. (Tervalent chromium salts exhibit an analogous behavior.) The color reactions are selective if the test solution is treated with a shght excess of magnesium carbonate before the reagent is introduced. It is essential that sulfuric acid be used for the acidification if hydrochloric acid is employed the zirconimn compounds formed at the same time remain unchanged. The sulfuric acid probably decomposes the colored zirconium compounds through formation of complex zirconium sulfuric acids. Chrome Fast Pure Blue B is the best reagent because its dye acid can be completely extracted by ether, which is not true of some of the related dyes. 

Assay of beryUium metal and beryUium compounds is usuaUy accompHshed by titration. The sample is dissolved in sulfuric acid. Solution pH is adjusted to 8.5 using sodium hydroxide. The beryUium hydroxide precipitate is redissolved by addition of excess sodium fluoride. Liberated hydroxide is titrated with sulfuric acid. The beryUium content of the sample is calculated from the titration volume. Standards containing known beryUium concentrations must be analyzed along with the samples, as complexation of beryUium by fluoride is not quantitative. Titration rate and hold times ate critical therefore use of an automatic titrator is recommended. Other fluotide-complexing elements such as aluminum, sUicon, zirconium, hafnium, uranium, thorium, and rate earth elements must be absent, or must be corrected for if present in smaU amounts. Copper-beryUium and nickel—beryUium aUoys can be analyzed by titration if the beryUium is first separated from copper, nickel, and cobalt by ammonium hydroxide precipitation (15,16). 

Jordan and coworkers have recently prepared several ansa-bis(indenyl) compounds (AlMe2L)indenyl 2SiMe2 and 1,2- (AlMe2L)indenyl 2C2H4 (L = THE, Et20, 1,4-dioxane) by a salt metathesis route. These were reacted with M(NMc2)4 (M = Zr, Hf) to eliminate [Me2AlNMc2]2 and form ansa-metallocene complexes of bis(dimethylamido)zirconium and bis(dimethylamido)hafmum. A simple tris(indenyl)aluminum compound has been prepared by reaction of bis(indenyl)mer-cury with aluminum metal. ... 

Since the addition of HCN to carbonyl compounds proceeds in the presence of a catalytic base, asynunetric cyanation should also be possible by using metal alkoxides such as boron, aluminum, titanium, zirconium, and lanthanoids through modification with an optically active substituent or ligand. Mori and Inoue reported that the titanium complex of an acyclic dipeptide composed of... 

IDouble Alkoxides. Complex double alkoxides are formed when a solution of an alkali or alkaline earth metal alkoxide is added to a solution of an alkoxide of aluminum, titanium, or zirconium and a series of such compounds have been prepared (44). 

Low-viscosity metal compounds are also used in cross-linking reactions. For example, alcoholates of aluminum, titanium, and zirconium as well as their complexes with volatile ligands are primarily employed. The reaction involves substitution of the alcohol and formation of a coordination compound with the binder [3.33]. 

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