Beryllium organometallic compounds

An unusual type of organometallic compound of beryllium is that in which it is coordinated to a cyclopentadienyl ring ... 

The structure of beryllium(II) chloride in its various phases has been described, together with the relevant thermochemistry, in Section 3.3. The dimer Be2Cl4 is an example of scheme (2) bonding, while the chain structure of BeCl2(s) represents scheme (3). Scheme (2) is rather unusual, and in compounds stable at room temperature it is mainly restricted to some organometallic compounds of Be. The example given in Table 6.3 has the structure ... 

Of the organometallic compounds of Group II elements, undoubtedly the chemistry of the magnesium compounds is best known. By contrast, the remaining elements in this group have received less attention and it is only recently that more information on organo derivatives of beryllium and, to lesser extent, of calcium, strontium, and barium has become available. Therefore, most of the observations regarding redistribution equilibria have been of more or less qualitative nature. 

The organometallic compound chemistry of the 2A metals is similar to that of the 1A metals, and ionically bonded compounds predominate. As is the case with lithium in group 1 A, the first 2A element, beryllium, behaves atypically, with a greater covalent character in its metal-carbon bonds. 

Be and Mg form an extensive range of organometallic compounds, those of Ca, Sr, and Ba being much more reactive and difficult to characterise. Beryllium alkyls such as Be(CH3)2 have chain structures with... 

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. 

Beryllium and magnesium have a formal oxidation state of +2 in their compounds see Oxidation Number) other oxidation states appear to exist only as transient reaction intermediates. Therefore, organometallic compounds of general formula R2M and RMY may exist, in addition to the nonorganometallic MY2. 

Redox Exchange of Magnesium or Beryllium Metal with Organometallic Compounds... 

The mercury may be replaced from mercury dimethyl by sodium, magnesium, zinc, or aluminium under suitable condition with formation of organometallic compounds of these metals with mercury diethyd, the reaction takes place with sodium, magnesium, cadmium, beryllium, zinc, aluminium, bismuth, and tellurium with mercury di-n-propyl, the metals sodium, beryllium, zinc and aluminium react, and sodium also reacts with mercury di-n-octyl. 

Only one bimetallic mechanism is presented here, as an example, the one originally proposed by Natta. He felt that chemisorptions of the organometallic compounds to transition metal halides take place during the reactions. Partially reduced forms of the di- and tri-chlorides of strongly electropositive metals with a small ionic radius (aluminum, beryllium, or magnesium) facilitate this. These chemisorptions result in formations of electron-deficient complexes between the two metals. Such complexes contain alkyl bridges similar to those present in dimeric aluminum and beryllium alkyls. The polymeric growth takes place from the aluminum-carbon bond of the bimetallic electron-deficient complexes . ... 

Longi and Mazzochi describe the gas chromatography of the organometallic compounds of beryllium, zinc, boron, aluminium and antimony. 

There is a dearth of structural information about the mixed organometallic compounds. Lithium aluminum tetraethyl is isostructural with dimethyl-beryllium (42), as one might expect after noting that the ratio of metal atoms to alkyl groups is the same in the two compounds. The structure of LlA1(C2H5)4 is shown in Fig. 7 the relevant bond distances and angles are... 

Trialkylaluminum and alkylaluminum hydrides associate with alkyl or hydride bridges. Since there are no available lone-pair electrons with which to form bridges by standard two-center two-electron interactions, multicenter bonding is invoked in the same manner as for electron-deficient boranes (see Boron Hydrides), alkyllithium (see Alkali Metals Organometallic Chemistry), dialkylberyllium and dialkylmagnesium compounds (see Beryllium Magnesium Organometallic Chemistry). 

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