Cationic metal carbonyls cobalt

Carborane-metal complexes, 8, 87-113 Catalysis by organometallics carbonylation, 6, 158-163 hydroformylation, 6, 128-136 olefin reactions, 7, 199-202 organic syntheses by nickel compounds, 8, 48-83 reviews, 10, 331-336 Cationic metal carbonyls, 8, 117-159 Chromium carbonyls, 8, 133-159, see also Benchrotrenes Cobaloximes, 7, 161, 203 Cobalt carbonyl, 6, 119-163 8, 152-155 Cotton-Kraihanzel method, 10, 213-214 Coupling reactions, on nickel, 8, 30-39, 82-83... 

Transition metal carbonyls such as Co2(CO)8 and CoH(CO)4, formed in the reaction of R3SiH with dimer (but also Fe(CO)5 and M3(CO)i2 (M = Fe, Ru, Os)) have been found to be active catalysts for the hydrosilylation of olefins, dienes, unsaturated nitriles, and esters as well as for hydrosilylation C=0 and C=N bonds [56]. Hydrosilylation of phenylthioacetylenes in the presence of this catalyst is extremely regioselective [57]. Cobalt(I) complexes, e. g., CoH(X)2L3 (X = H, N), could be prospective candidates for investigation of the effectiveness of alkene hydrosilylation by trialkoxysilanes as well as dehydro-genative silylation [58]. Direct evidence for the silyl migration mechanism operative in a catalytic hydrosilylation pathway was presented by Brookhart and Grant [59] using the electrophilic Co cationic complex. 

Many carbonyl and carbonyl metallate complexes of the second and third row, in low oxidation states, are basic in nature and, for this reason, adequate intermediates for the formation of metal— metal bonds of a donor-acceptor nature. Furthermore, the structural similarity and isolobal relationship between the proton and group 11 cations has lead to the synthesis of a high number of cluster complexes with silver—metal bonds.1534"1535 Thus, silver(I) binds to ruthenium,15 1556 osmium,1557-1560 rhodium,1561,1562 iron,1563-1572 cobalt,1573 chromium, molybdenum, or tungsten,1574-1576 rhe-nium, niobium or tantalum, or nickel. Some examples are shown in Figure 17. 

The carbon dioxide anion-radical was used for one-electron reductions of nitrobenzene diazo-nium cations, nitrobenzene itself, quinones, aliphatic nitro compounds, acetaldehyde, acetone and other carbonyl compounds, maleimide, riboflavin, and certain dyes (Morkovnik and Okhlobystin 1979). The double bonds in maleate and fumarate are reduced by CO2. The reduced products, on being protonated, give rise to succinate (Schutz and Meyerstein 2006). The carbon dioxide anion-radical reduces organic complexes of Co and Ru into appropriate complexes of the metals(II) (Morkovnik and Okhlobystin 1979). In particular, after the electron transfer from this anion radical to the pentammino-p-nitrobenzoato-cobalt(III) complex, the Co(III) complex with thep-nitrophenyl anion-radical fragment is initially formed. The intermediate complex transforms into the final Co(II) complex with the p-nitrobenzoate ligand. 

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