Metallo-organic compounds

Ilic, M. R., Jovanic, P. B., Radosevic, P. B. and Rajakovic, L. V., Sorption of hydrogen cyanide onto activated carbon cloth impregnated with metallo-organic compounds, Sep. Sci. Technol., 1995, 30(13), 2707 2729. 

Chemical Reactivity - Reactivity with Water No reaction Reactivity with Common Materials May attack some forms of plastics Stability During Transport Stable Neutralizing Agents for Acids and Caustics Not pertinent,- Polymerization Hazardous polymerization unlikely to occur except when in contact with alkali metals or metallo-organic compounds Inhibitor of Polymerization 10 -20 ppm tert-butylcatechol. 

These ideas might be used to explain the interesting results obtained recently by Williams et al.53 These workers observed formation of crystalline polystyrene when the reaction was initiated by triphenyl methyl potassium (or some other potassium metallo-organic compounds) in a hexane solution, but an amorphous polymer was formed in benzene. They point out that the catalyst is soluble in benzene but insoluble in hexane, and suggest that the heterogeneity of the catalyst is responsible for the results. Although this might be the case, an alternative explanation could be advanced.42 1... 

In the following sections, the major categories of metallo-organic compounds used in CVD are reviewed. Others are described in the review of materials produced by CVD in Chs. 6-12. These metallo-organics form only a small proportion of the total number of compounds available and there are many that could be profitably investigated. 

Most metallo-organic compounds are monomers with some important exceptions, such as trimethyl aluminum which is a dimer. Their vapor pressures are usually directly related to the molecular weight, with the lower molecular weight compounds having the higher volatility. 

To be useful as CVD precursors, a metallo-organic compound should be stable at room temperature so that its storage and transfer are not a problem. It should also decompose readily at low temperature, i.e., below 500°C. The compounds listed in Table 4.1 meet these conditions with the exception of the alkyls of arsenic and phosphorus, which decompose at higher temperatures. For that reason, the hydrides of arsenic and phosphorus are often preferred as CVD precursors (see Ch. 3). These hydrides however are extremely toxic and environmental considerations may restrict their use. 

Deposition occurs at much lower temperature (260-340°C) by the decomposition of metallo-organic compounds such as copper acetylacetonate, Cu(C5H202)2 or by the hydrogen reduction of the copper chelate, Cu(C5HFg02)2 at and more recently of... 

Beryllium carbide, Be, produced by the pyrolysis of metallo-organic compounds. 

MOCVD of Sn02. Tin oxide is obtained by the oxidation of the metallo-organic compound tetramethyl tin at atmospheric pressure or at low pressure (<1 Torr) in the range of350-600°C, typically... 

It is remarkable that LDF theory also describes the bond length and vibrational frequency of the fluorine molecule with the same error bar as the other systems discussed here. This finding is significant as it shows that the error made in the LDF approach appears to be consistent in a wide class of different systems. In fact, recent calculations on ferrocene (52) show that also this type of metallo-organic compound does not present an exception - the Fe/ring distance agrees within 0.002 A with experiment. 

Metallo-organic compounds possess high reactivity to water, oxygen and nearly all organic solvents, except hydrocarbons and ethers. Chemical properties of the suggested surface complexes of the type M )f in presence of various solvents are unknown. However,... 

High stability metallo-organic compounds such as porphyrin, phthalocyanine, metallized... 

For polymeric CSD processes, three classes of metal organic (metallo-organic) compounds are used most often as starting reagents metal alkoxides, metal carboxylates, and metal beta-diketonates. These species differ in their solubility and reactivity, as well as their tendency to react with one another, all of which are factors that may influence starting reagent selection. Representative structures of these classes of precursors are illustrated in Fig. 2.2.8... 

The approach typically consists of dissolving the metallo-organic compounds in a common solvent, typically xylene, in the desired stoichiometry. The long-chain length associated with the organic moieties of these compounds increases their dissolution tendency and concomitantly limits their hydrolysis tendency. Therefore, compared with the sol-gel and chelate pro-... 

Organic and Metallo-Organic Compounds in Heterogeneous Systems... 

As activated charcoal, metallo-phthalocyanines and solid free radicals catalyze these reactions, they form the oldest example of heterogeneous catalysis by organic and metallo-organic compounds. 

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