Metallorganic compounds

Dehydration-Halogenation-Activation and Silylation of Inorganic and Organic Salts and Metallorganic Compounds... 

Cambridge Structural Database (CSD). Cambridge Crystallographic Data Centre, University Chemical Laboratory, Cambridge, UK. Electronic database of crystal structures of organic and metallorganic compounds. www.ccdc.cam.ac.uk. 

Sokol, V. I. Porai-Koshits, M. A. Butman, L. A. Proc. Semin. Crystallochem. Coord. Metallorganic Compounds, Bratislava (Czechoslovakia), 1973. 

The stereospecific polymerization of a-olefins takes place only in the presence of heterogeneous catalytic systems, including a crystalline substrate (formed by halides of transition metals, such as TiCb, TiCb, VCI3, CrCla, C0CI2, etc.) and a suitable metallorganic compound (5). 

Such metallorganic compound or coordination complex contains an electropositive metal for which the carbon-metal bond may be considered at least partly polarized, so that the carbon atom has a partially ionic character and behaves as a carbanion. 

The above-mentioned metallorganic compounds must have the property of forming complexes with the halides of transitions metals. It is required, in order to get catalytic complexes, that the metal of metallorganic compounds be able to create a strong localized electric field therefore, metals having a very small ionic diameter (below 1 A.) jointly with a very electropositive character are to be used. For such reasons, metals such as Ca,... 

The formation of prevailingly electron-deficient complexes between transition metals of low valency and metallorganic compounds of metals having small ionic radius has been clearly shown. The electron-deficient metallorganic compounds... 

The metallorganic compounds (I, II) employed in presence of a heterogeneous phase containing an amorphous compound of a low-valency, strongly electropositive transition metal, generally polymerize a-olefins to amorphous polymers. In a similar fashion, the soluble reaction products of such metallorganic compounds with compounds of transition metals, chemisorbed on amorphous substrates, polymerize a-olefins to amorphous polymers 6, 9). 

Complexes of type III and also traces of soluble halides of strongly electropositive transition metals, being able to form complexes with metallorganic compounds of the type I, II, increase the activity of the stereospecific catalysts formed by the action of metallorganic compounds on crystalline substrates 10,11). They can also polymerize in a stereospecific way in the presence of crystalline substrates of transition metals (for instance, CoCU) which are not by themselves sufficiently electropositive, (when used in the presence of metallorganic compounds) to polymerize the a-olefins 10, 11). 

The stereospecificity depends not only upon the electropositivity and the ionic radius of the metal which belongs to the metallorganic compound, used for the preparation of the catalyst, but also upon the lattice structure of the crystalline substrate made of the transition metal compound (5). 

These systems may be differentiated either by the nature of the compound of the transition metal or by the type of the metallorganic compound used for their preparation. 

It has been observed that other metallorganic compounds (e.g., Zn(C2H6)2, which is not associated as A1(C2H6)3) can be involved in chain transfer processes (45). In this case presumably alkyl groups are exchanged as follows ... 

In all tests, the initial treatment of a-titanium trichloride, with the ethyl-aluminum solution, was carried out under conditions suitable for the practically complete saturation of the a-titanium trichloride surface at the temperature considered by the metallorganic compound. 

G. Pilcher, Thermodynamics of Organic Metallorganic Compounds , Academic Press, NY... 

The applications of CIDNP to mechanistic studies of organic photochemical reactions are numerous, but only a few systems, such as the photoreduction of quinones, have been fully examined by both CIDEP and CIDNP methods. Instead of repeating some of the well-known CIDNP mechanistic studies summarized in other reviews, we shall go into a relatively new area of CIDNP studies involving metallorganic compounds. 

Several B metals, the borderline metal Co, and all metalloid metals can form element-carbon bonds that are stable in water. Metallorganic compounds of A ions and of borderline ions (exception Co) hydrolyze in contact with water. Methylation and alkylation are common reactions in biological systems they may also proceed abiotically and generate methyl- or alkyl-element compounds. Examples include selenide, selenoamino acids, methylarsenic acid (MM A A), and dimethylarsenic acid (DM A A) ... 

Redox reactions. With the help of special redox agents, new compounds, complexes, or metallorganic compounds with special valence states could be prepared under hydro(solvo)thermal conditions. Complete oxidation of organic compounds could be conducted under supercritical conditions as well. 

Pesticides and bacteriocides Metallorganic compounds Dichlorobenzonitrile Tetrabutyl tin Methyltriclosan ... 

It has also been found that acetone and other entrainers including water, DMF and ethanol, have no effect at aU on the solubility of the three insoluble metallorganic compounds [42]. 

Wss = weight percent of considered metallorganic compound (which is at saturation)... 

Recent results in the field of catalytic oxidations with hydrogen peroxide are reviewed. Most effective catalysts fall into three categories metallorganic compounds, phase-transfer catalysts, redox zeolites. Metalloporphyrins and Pt-phosphine complexes are representative of first category. Mo and W polyoxome-talates and related systems, in association with phase transfer agents, belong to the second one. Titanium silicalite (TS-1) is the most studied redox zeolite. The oxidation of nitrogen and sulphur compounds and Fenton-like reactions are not reviewed. 

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