Aluminum organometallic compounds

Gas-phase reaction pathways of aluminum organometallic compounds with dimethylaluminum hydride and alane as model systems ... 

Hexacarbonylmolybdenum was synthesized in low yields by L. Mond by the reaction of pyrophoric molybdenum with carbon monoxide. Presently, it is prepared by carbonylation of M0CI5, molybdic acid, molybdenum sulfide, and other molybdenum compounds. The following reducing agents may be employed Mg, Al, Na, Zn, Fe, Grignard reagents, aluminum organometallic compounds, etc. Sometimes such syntheses involve dry methods whereby no solvent is used. However, most commonly. 

Many cationic cycloheptatrienyl complexes are formed by reactions of various coordination compounds with CyHg in the presence of aluminum chloride or aluminum organometallic compounds/" ... 

The synthesis of cyclooctatetraene complexes may be carried out utilizing many other reducing agents such as metallic sodium and magnesium, aluminum organometallic compounds, etc. 

Other organometallic compounds of aluminum include the alkyl hydrides, R2A1H. Molecular association of these compounds leads to cyclic tetramers. When the dimeric and trimeric compounds are dissolved in a basic aprotic solvent, the aggregates separate as a result of formation of bonds between A1 and the unshared pair of electrons on the solvent molecule. Toward Lewis bases such as trimeth-ylamine, aluminum alkyls are strong Lewis acids (as are aluminum halides). 

A) Ziegler method Catalyst systems can be prepared by reacting a nickel(II) salt with an organometallic compound of the main group metals but aluminum is preferred. 

Ethyl 2,3-epoxypropanoate is a very interesting chiron. It may be opened by various organometallic compounds such as dialkyl, diaryl, and divinyl lithium cuprates, dialkylmagnesium cuprates, trialkylalanes and aluminum acetylides.5 6 The epoxide ring is attacked regiospecifically at the p-position and produces a-hydroxy esters exclusively without racemization. The same result is observed with... 

Complex hydrides were used for reductions of organometallic compounds with good results. Trimethyllead chloride was reduced with lithium aluminum hydride in dimethyl ether at —78° to trimethylplumbane in 95% yield [1174, and 2-methoxycyclohexylmercury chloride with sodium borohydride in 0.5 n sodium hydroxide to methyl cyclohexyl ether in 86% yield [1175]. 

Water, alcohols, ethers, or amines can cause inhibition of ionic polymerization. However, these substances can act in different ways according to their concentration. For example, in polymerizations initiated by Lewis acids (BF3 with isobutylene) or organometallic compounds (aluminum alkyls), water in small concentrations behaves as a cocatalyst, but in larger concentrations as an inhibitor (reaction with the initiator or with the ionic propagating species). 

The low-pressure polymerization of olefins using Ziegler-Natta catalysts, i.e., mixtures of compounds of transition groups IV to VI of the periodic table of the elements together with organometallic compounds of groups I to III is widely applied. Such catalysts, consist of titanium alkyl compounds and aluminum alkyl compounds or alkylaluminum halides. 

Results of the polymerization of propylene oxide by these four kinds of organometallic compounds showed that the zinc compounds are superior to the aluminum compounds with respect to their stereoregulating power. It is noteworthy that the zinc catalyst is generally superior to the aluminum catalyst as the stereospedfic polymerization catalyst. Among the two organozinc compounds, EtZnNBu ZnEt was thought to be more suitable than EtZnNHBu for detailed studies, because the former was monomeric and had no reactive hydrogen atom. 

Recently, stable organometallic compounds derived from Ni(acac)2 have been described. The square planar compounds [Ni(acac)(PR3)L] (R = Ph, Cy L = Me, Et) were obtained by reacting Ni(acac)2 and PR3 in ether at -20 °C with either diethyl- or dimethyl-aluminum monoethoxide.1546,1547,1577 [Ni(acac)(Me)PPh3] reacts with diphenylacetylene at room temperature, according to equation (183).1578... 

Catalyst Components. The components for the organometallic mixed catalysts n are suitable compounds of practically any transition metal of Groups IV to VIII, on the one hand, and compounds with at least one C—M bond, M being a metal of Groups I—III (especially aluminum ) and some others, on the other hand. Instead of organometallic compounds some other products can be used, for instance, hydrides. In such cases true metal alkyls are very probably formed during the polymerization process. Since not only the special combination of the two components but also their... 

In addition to the redistributions discussed above which involve exchanges on aluminum atoms only, there is a great deal of literature available on the exchange reactions of aluminum alkyls with halides, oxides, and alkoxides of other elements which undoubtedly are also equilibrium reactions. These, however, have found great interest as methods for the syntheses of organometallic compounds in general 129, 130). It appears that the equilibria in these systems lie almost completely at the side of the alkyl compound of the other element. 

Organometallic compounds, obtained in a US field and having nonstandard structures, were reported [745,746]. Thus, organic halides produce, with aluminum and palladium, the following products 832 [Scheme (3.287)] ... 

Synthetic routes include anionic, cationic, zwitterionic, and coordination polymerization. A wide range of organometallic compounds has been proven as effective initiators/catalysts for ROP of lactones Lewis acids (e.g., A1C13, BF3, and ZnCl2) [150], alkali metal compounds [160], organozinc compounds [161], tin compounds of which stannous octoate [also referred to as stannous-2-ethylhexanoate or tin(II) octoate] is the most well known [162-164], organo-acid rare earth compounds such as lanthanide complexes [165-168], and aluminum alkoxides [169]. Stannous-2-ethylhexanoate is one of the most extensively used initiators for the coordination polymerization of biomaterials, thanks to the ease of polymerization and because it has been approved by the FDA [170]. 

Pentamethylantimony was the first It6Sb species to be obtained by Wittig and Torssell in 1955 (104) Various other derivatives of this type have since been synthesized, and a range of preparative methods has been described. Among these are the alkylation of RiSbX, R3SbX2, and SbX species with organometallic compounds of lithium, magnesium, aluminum,... 

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