Zirconiums aluminum halides

Reduction of ZrIV in ZrX4-Al2X6 (X = Cl, Br or I) melts, with either zirconium or aluminum metal, yields soluble blue species. These species were not isolated, but they have been formulated as Zr(X2AlX2)3 complexes on the basis of their electronic spectra. Absorption bands at 17 400 (X = C1), 16 000 (X = Br) and 14 000 cm-1 (X = I) may be assigned to the 2t -2es transition of Zr111 in an octahedral environment of halide ions. The solid zirconium(III) halides exhibit ligand-field bands at closely similar frequencies.32... 

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). 

Lead dioxide Aluminum carbide, hydrogen peroxide, hydrogen sulfide, hydroxylamine, ni-troalkanes, nitrogen compounds, nonmetal halides, peroxoformic acid, phosphorus, phosphorus trichloride, potassium, sulfur, sulfur dioxide, sulfides, tungsten, zirconium... 

As shown in Table IV, the highest catalytic activity of metal halides used as Lewis acid for the alkylation reaction of ferrocene with 2 was observed in methylene chloride solvent. Among Lewis acids such as aluminum chloride, aluminum bromide, and Group 4 transition metal chlorides (TiCl4, ZrCU, HfCU), catalytic efficiency for the alkylation decrea.ses in the following order hafnium chloride > zirconium chloride > aluminum chloride > aluminum bromide. Titanium chloride... 

AICI3 is a moisture-sensitive and strong Lewis acid. It is a first choice for Friedel-Crafts-type reactions, which provide numerous important transformations in laboratory and industry. It can also be applied to the transformation of alkenes to ketones via alkylaluminum halides.303 Hydrozirconation of an olefin and subsequent transmetalation from zirconium to aluminum gives the corresponding alkylaluminum dichloride, and the subsequent acetylation by acetyl chloride affords the corresponding ketone in high yield (Scheme 66). 

Looking for a more efficient catalyst to carry out this reaction thus became the most important issue. To achieve this, a large number of common Lewis acids were screened, including the halides of aluminum, iron, zinc, titanium, zirconium, nickel, copper, tin and lead. A number of these compounds did show activities as ether cleavage catalysts. The most effective catalysts were the halides... 

Alkenyl-aluminum and -zirconium derivatives have been found to couple with allyl halides in the presence of Pd° catalysts (equation 38), although simple alkyl-aluminum and -zirconium reagents fail in the reaction.154 The 1,4-dienes thus generated are important intermediates in organic synthesis. 

Excision reactions are sometimes accompanied by redox chemistry. For example, dissolution of the 2D solid Na4Zr6BeCli6 in acetonitrile in the presence of an alkylammonium chloride salt results in simultaneous reduction of the cluster cores (144). Here, the oxidation product remains unidentified, but is presumably the solvent itself. As a means of preventing such redox activity, Hughbanks (6) developed the use of some room temperature molten salts as excision media, specifically with application to centered zirconium-halide cluster phases. A number of these solids have been shown to dissolve in l-ethyl-2-methylimidazolium chloride-aluminum chloride ionic liquids, providing an efficient route to molecular clusters with a full compliments of terminal chloride ligands. Such molten salts are also well suited for electrochemical studies. 

Ziegler-Natta Catalysts (Heterogeneous). These systems consist of a combination of a transition metal compound from groups IV to VIII and an organometallic compound of a group I—III metal.23 The transition metal compound is called the catalyst and the organometallic compound the cocatalyst. Typically the catalyst is a halide or oxyhalide of titanium, chromium, vanadium, zirconium, or molybdenum. The cocatalyst is often an alkyl, aryl, or halide of aluminum, lithium, zinc, tin, cadmium, magnesium, or beryllium.24 One of the most important catalyst systems is the titanium trihalides or tetra-halides combined with a trialkylaluminum compound. 

In the 1940 s a CVD process using a flame to produce homogeneously nucleated (powder) oxides of titanium, zirconium, iron, aluminum, and silicon was reported. A mixture of metal halide vapor and oxygen is injected through the central nozzle of a burner, with fuel gas and supplemental oxygen provided through two concentric outer rings. At 950°C to 1100 C flame temperature, the metal halide vapor decomposes to form very fine oxide powders. 

R-X = alkenyl and atyl halides and triflates R M = alkenyl and aryl zinc, aluminum, zirconium, or boron and tin... 

Selenenyl halides also react similarly with copper enolates, aluminum enolates, and zirconium enolates [101]. Scheme 15.38 illustrates the selenenylation of copper enolates generated by conjugate addition of lithium diphenylcuprate to cyclo-pentenone [100 d]. 

Most commonly, the catalyst component consists of halides or oxyhalides of titanium, vanadium, chromium, molybdenum, or zirconium, and the cocatalyst component often consists of an alkyl, aryl, or hydride of metals such as aluminum, lithium, zinc, tin, cadmium, beryllium, and magnesium. The catalyst systems may be heterogeneous (some titanium-based systems) or soluble (most vanadium-containing species). Perhaps the best known systems are those derived from TiCl4 or TiCls and an aluminum trialkyl. 

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