Ruthenium complexes trinuclear carbonyls

This observation may well explain the considerable difference between metal-olefin and metal-acetylene chemistry observed for the trinuclear metal carbonyl compounds of this group. As with iron, ruthenium and osmium have an extensive and rich chemistry, with acetylenic complexes involving in many instances polymerization reactions, and, as noted above for both ruthenium and osmium trinuclear carbonyl derivatives, olefin addition normally occurs with interaction at one olefin center. The main metal-ligand framework is often the same for both acetylene and olefin adducts, and differs in that, for the olefin complexes, two metal-hydrogen bonds are formed by transfer of hydrogen from the olefin. The steric requirements of these two edgebridging hydrogen atoms appear to be considerable and may reduce the tendency for the addition of the second olefin molecule to the metal cluster unit and hence restrict the equivalent chemistry to that observed for the acetylene derivatives. 

Treatment of (80) and (81) with Ru3(CO)12 gave the >/4-silatrimethylenemethane-ruthenium complexes in 9% and 22% yield, respectively. The major product of the Z-alkylidenesilacyclopropane reaction was trinuclear ruthenium carbonyl cluster (82), whose structure was established by x-ray diffraction (Equation (37)). This appears to be the first example of a main group metal-bound carbonyl inserting into a silacyclopropane <9lJA279i, 94OM4606). 

Photochemical Activation. Coordinative unsaturated fragments may also be produced by photolytic reactions. In presence of UV-irradiation metal carbonyl compounds lose sequentially CO-ligands. Electron-deficient, solvent coordinated species produced in this way may combine with inactivated metal complexes via the formation of donor-acceptor metal-metal bonds. Iron, ruthenium, and osmium trinuclear carbonyl clusters may be prepared by this way ... 

Au-B bonds are also present in metal clusters with intersticial or peripheral boron atoms. An example is the cluster [Fe4(CO)12BH(AuPPh3)2], which was prepared by reaction of [AuCl(PPh3)] with the carbonyl iron dihydride. With the oxonium salt the reaction proceeds to the trinuclear gold derivative [Fe4(CO)12B(AuPPh3)3] (357).2063-2070 The ruthenium analogues and complexes with other ligands have been also synthesized as, for example, (358).2071-2079... 

Grignard additions, 9, 59, 9, 64 indium-mediated allylation, 9, 687 in nickel complexes, 8, 150 ruthenium carbonyl reactions, 7, 142 ruthenium half-sandwiches, 6, 478 and selenium electrophiles, 9, W11 4( > 2 in vanadocene reactions, 5, 39 Nitrites, with trinuclear Os clusters, 6, 733 Nitroalkenes, Grignard additions, 9, 59-60 Nitroarenes, and Grignard reactivity, 9, 70 Nitrobenzenes, reductive aminocarbonylation, 11, 543... 

All three Group 8 metals form trinuclear clusters M3(CO)i2. However, while all carbonyl ligands in ruthenium and osmium dodecacarbonyl complexes coordinate to the metal center as terminal carbonyls, there are two bridged carbonyl groups in iron dodecacarbonyl. This may be due to the smaller van der Waals radius of the iron atom. In this section, Fe(CO)5, Fe2(CO)9and Na2[Fe(CO)4] are reviewed. 

Known carbonyl hydrides of ruthenium include the unstable HRu(CO)4, as well as the trinuclear H2Ru3(CO)n, tetranuclear H2Ru4(CO)i3 and H4Ru4(CO)i2, and complexes of even higher nuclearity, as well as substitution and deprotonation derivatives. A special feature of ruthenium carbonyl chemistry is the existence of series of carbonyl... 

The most extensive studies of the chemistiy of cluster complexes have been associated with the trinuclear cluster unit, as may be anticipated. A wide range of substitution reactions has been demonstrated for both Ru3(CO)i2 and Os3(CO)i2, with the full range of ligands normally employed in the study of metal carbonyl chemistry. In genera 1, the trinuclear osmium cluster is more readily maintained, ruthenium often giving rise to cluster breakdown, yielding mononuclear and binu-clear adducts. This reflects the increased bond enei of the metal-metal bond on descending the triad (see Table X later in this section). 

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