Rhodium with organometallic compounds

The coordination of the alkyne to the rhodium catalyst allows the carborhodation of the triple bond to afford the vinylrhodium intermediate 47 (Scheme 14). The rearrangement of this organometallic compound into the 2-(alkenyl)phenylrhodium intermediate 48 is evidenced by one deuterium incorporation resulting from the deuter-iolysis of the Rh-C bond. The addition of the phenylrhodium intermediate 45 must occur before its hydrolysis with water. The 2-(alkenyl)phenylrhodium intermediate 45, generated by the phenylrhodation of an alkyne followed by... 

Organometallic compounds, 14 550-551 25 71. See also Organometallics carbides contrasted, 4 648 as initiators, 14 256-257 iridium, 19 649-650 molybdenum(III), 17 27 osmium, 19 642-643 palladium, 19 652 platinum, 19 656-657 reaction with carbonyl groups, 10 505-506 rhodium, 19 645-646 ruthenium, 19 639 sodium in manufacture of, 22 777 titanium(IV), 25 105-120 Organometallic fullerene derivatives,... 

The reaction of bis-phenylpropargyl ether (321) with tris(triphenylphosphine)rhodium chloride in benzene or toluene led to the formation of the unusual organometallic compound (322), which can be viewed as a derivative of an oxygen-rhodium pentalene system. Reaction of the rhodium complex (322) with sulfur leads to the corresponding 4,6-diphenyl-l,3-dihydro[3,4-c]furan (323). The selenium and tellurium analogs (324) and (325) were made in a similar manner (Scheme 111) (76LA1448). 

In some cases, it is possible to couple an alcohol with an organometallic compound. Allylic alcohols are coupled with alkylmagnesium bromides in the presence of Ti(OiPr)4, for example. Allylic alcohols can be coupled with arylboronic acids in ionic liquid solvent and a rhodium catalyst. The palladium-catalyzed... 

Organometallic compounds of rhodium have the metal center in oxidation states ranging from +4 to -3. but the most common oxidation states are +1 and +3. The Rh(I) species have a d electron configuration and both four coordinated square planar and five coordinated trigonal bipyramidal species exist. Oxidative addition reactions to Rh(I) form Rh(III) species with octahedral geometry. The oxidative addition is reversible in many cases, and this makes catalytic transformations of organic compounds possible. Presented here are important reactions of rhodium complexes in catalytic and stoichiometric transformations of organic compounds. 

Enhanced catalytic activity has also been observed for the hydroformylation of oct-l-ene and dec-l-ene with water-soluble phosphine-caltK[4]arene—rhodium complexes (Figure 32). " These organometallic compounds behave, not only as homogeneous metal catalysts but also as inverse phase-transfer catalysts, that is, they perform a dual functional catalysis. The olefin is believed to be included in the hydrophobic cavity and to simultaneously interact with a catalytic transition metal center coordinated to the phosphine moieties. 

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. 

The controlled surface reaction of an organometallic compound, such as tetrabutyl tin, with hydrogen covered rhodium particles supported on silica leads to a very well defined superficial organometallic species. These superficial organometallic species are characterized by rhodium-tin bonds and contains butyl radicals still linked to tin atoms. As the temperature of the hydrogen thermal treatment is increased, butyl radicals are progressively eliminated leading at last to the formation of bulky rhodium-tin alloy particles. 

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