Subject reactions with organometallic compounds

The accurate determination of rate constants for the reactions of 19F atoms is often hampered by the presence of reactive F2 and by the occurrence of side reactions. The measurement of the absolute concentration of F atoms is sometimes a further problem. The use of thermal-ized 18F atoms is not subject to these handicaps, and reliable and accurate results for abstraction and addition reactions are obtained. The studies of the reactions of 18F atoms with organometallic compounds are unique, inasmuch as such experiments have not been performed with 19F atoms. In the case of addition reactions, the fate of the excited intermediate radical can be studied by pressure-dependent measurements. The non-RRKM behavior of tetraallyltin and -germanium compounds is very interesting inasmuch as not many other examples are known. The next phase in the 18F experiment should be the determination of Arrhenius parameters for selected reactions, i.e., those occurring in the earth s atmosphere, since it is expected that the results will be more precise than those obtained with 19F atoms. 

The methodology of the addition of tin into supported platinum or rhodium seems to play an important role in the behaviour of the active phase obtained. Controlled surface reactions of organometallic compounds with metal surfaces result in the formation bimetallic systems with specific properties in the hydrogenation of different unsaturated compounds. ° However, the nature of the Sn-Pt or Sn-Rh bimetallic phase formed, and its influence on the final properties of the catalyst, have not been yet well determined and this is still a subject to be investigated. 

Combustion of transition metal organometallic compounds produces a mixtures of simple compounds (metal oxides, carbon oxides, water, nitrogen) which is subject to exact analysis. Thermal decomposition or high temperature iodination of the same compounds cannot necessarily be expected to produce simple materials, with the result that identification is often a difficult problem. This is typified by diene derivatives of iron carbonyl10, where side reactions of the dienes (e.g. polymerization) follow disruption of the iron-diene bonds. The oligomeric mixture can be parti-... 

These are very facile processes, and here this subject is divided into reaction of halides with (i) organometallic compounds, (ii) reaction with carbonyl stabilized anions and (iii) reaction with other carbanions. 

Other examples have been provided by the anodically initiated isomerization of several decarbene metal carbonyl couples [197]. Electrochemical induction of chemical reactions can also be successfully used for conversion of alcoolates into ketones with simultaneous reduction of aromatic halides [198], the tetramerization of aziridines [199], or ligand substitution [200] in organometallic compounds. A useful review on this subject was published [201]. 

The photochemical properties of organometallic compounds are investigated, but none to the depth to which metal-carbonyl complexes are subjected. Photosensitivity of the complexes often is cited, but there is little emphasis on synthetic utility. This section examines the synthetic potential of the photochemical transformations. Studies that are concerned solely with mechanistic aspects are excluded, as well as synthetic applications of the mixed compounds, such as h -CjHjCr(CO)3 and h -CjHjMnfCOjj, where the primary photochemical reaction is CO loss these are discussed in 13.2.4. 

Rhodium and ruthenium complexes of 2,2 -bis(diphenylphosphino)-l,l -binaphthyl (BINAP) have frequently been used as catalysts for enantioselective hydrogenation of olefins and ketones." "" From consideration of the literature on this subject, it was proposed that the presence of a mono-oxidized BINAP in an organometallic catalyst could have interesting consequences." Accordingly, Rh(BINAP)(CO)Cl was prepared, and upon reaction with O2, (BINAP(0))Rh(CO)Cl was formed. These compounds were authenticated by X-ray crystallography, and IR and NMR spectroscopies. The kinetics of this reaction were monitored by solution (chloroform was the solvent) IR spectroscopy. In the absence of added CO, the oxygenated compound was formed in about 50% yield. BINAP(0)2 and CO2 are also produced. Plots of obs (from loss of reactant) versus [O2] at various temperatures yielded... 

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