Transition-metal—carbon bonds hydrogen

Olefinic compounds will often insert into carbon-transition metal bonds as CO does, and this reaction is an important step in many catalytic syntheses. When this step is combined with an oxidative addition of an organic halide to a palladium(O) complex in the presence of a base, a very useful, catalytic olefinic substitution reaction results (26-29). The oxidative addition produces an organopalladium(II) halide, which then adds 1,2 to the olefinic reactant (insertion reaction). The adduct is unstable if there are hydrogens beta to the palladium group and elimination of a hydridopalladium salt occurs, forming a substituted olefinic product. The hydridopalladium salt then reforms the... 

Pauling, L. (1977) "The nature of bonds formed by the transition metals with hydrogen, carbon, and phosphorus," Acta Crystal-logr., in press. 

Pauling, L. Nature of the Bonds Formed by the Transition Metals with Hydrogen, Carbon, and Phosphorus Acta Crystallogr. 1978, B34, 746-754. 

Brookhart, M. and Green, M.L.H. (1983) Carbon—hydrogen—transition metal bonds./. Organomet. Chem., 250, 395. 

M. Brookhart, and M. L. H. Green, Carbon-Hydrogen-Transition Metal Bonds,... 

Periodic Trends in Transition Metal Bonds to Hydrogen, Carbon, and Nitrogen... 

All of these reactions involve transition metals such as palladium, copper, and ruthenium, usually in complex with certain types of ligands. After we see the practical applications of these reactions for carbon—carbon bond formation, we shall consider some general aspects of transition metal complex structure and representative steps in the mechanisms of transition metal—catalyzed reactions. We shall consider as specific examples the mechanism for a transition metal—catalyzed hydrogenation using a rhodium complex called Wilkinsons catalyst, and the mechanism for the Heck—Mizoroki reaction. 

These M-C-H interactions were named agostic interactions by Brookhart and Green [13] in 1983. They reported in detail on agostic interactions in their 1988 review entitled Carbon-Hydrogen-Transition Metal Bonds [14]. ... 

Brookhart M, Green MLH (1988) Carbon-hydrogen-transition metal bonds. Prog Inorg Chem 36 1-124... 

Brookhart, M. Green, M.L.H. Wong, L.L. In Carbon-Hydrogen-Transition Metal Bonds Lippard, S.J., Ed. Progress in Inorganic Chemistry John Wiley Sons New York, NY, 1991 Vol. 36 pp 1-124. 

Brookhart, M. Green, M. L. H. Carbon-hydrogen-transition metal bonds. J. Organomet. Chem. 1983, 250, 395 08. 

We consider first some experimental observations. In general, the initial heats of adsorption on metals tend to follow a common pattern, similar for such common adsorbates as hydrogen, nitrogen, ammonia, carbon monoxide, and ethylene. The usual order of decreasing Q values is Ta > W > Cr > Fe > Ni > Rh > Cu > Au a traditional illustration may be found in Refs. 81, 84, and 165. It appears, first, that transition metals are the most active ones in chemisorption and, second, that the activity correlates with the percent of d character in the metallic bond. What appears to be involved is the ability of a metal to use d orbitals in forming an adsorption bond. An old but still illustrative example is shown in Fig. XVIII-17, for the case of ethylene hydrogenation. 

In addition to activation of sihcon bonds by fluoride ions as discussed in Section 2.4, silicon-silicon, silicon-carbon, silicon-hydrogen, and silicon-nitrogen bonds are activated by transition metal salts and transition metal complexes. Thus, hydrolysis of silicon-carbon bonds such as in phenyltrimethylsilane 81 can be induced by... 

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