Ruthenium carbonyls structures

The palladium and platinum metals also form carbonyl compounds. Of the expected compounds Pd(CO)4, Pt(CO)4, Ru(CO)5, Os (CO) 5, Mo-(CO)e, and W(CO)6 only Mo(CO)e has been prepared, although some unsaturated ruthenium carbonyls have been prepared. The compounds Pd(CO)2Cl2, Pt(CO)2Cl2, K[PtCOCl3], etc., show the stability of the four dsp2 bonds. It would be interesting to determine whether or not each CO is bonded to two metal atoms in compounds such as [Pt(CO)Cl2]2, whose structure is predicted to be... 

A similar range of reactions has also been reported for the ruthenium carbonyl-triphenylphosphine systems (148). In these systems, a high percentage of the products were dinuclear, reflecting the weaker bonding in the ruthenium system, and as for some of the osmium complexes discussed above, some contain orthometallated phenylphos-phine groups (see Fig. 29, structures I, IV, X). 

Experiments with cyclooctatetraene and its methyl and phenyl derivatives have demonstrated that reaction with certain ruthenium carbonyl complexes can occur with transannular bonding to give pentalene complexes directly.253,264 The structures of these unique molecules have been confirmed by X-ray crystallography. 

The reaction between acetylenes and ruthenium carbonyls produces a series of n complexes with cyclic ligands which, as in the iron system, have either the metal or a CO group incorporated into the ring. Accordingly, 3-hexyne 536) and hexafluoro-2-butyne 90) react with Ru3(CO)i2 to give the (substituted cyclopentadienone)tricarbonylruthenium complexes with structures presumably comparable to those of the iron complexes (93-95). Although diphenylacetylene will not react directly with Ru3(CO)i2 to produce this type of complex 536), it can be prepared 90) by treating Ru3(CO)i2 with tetracyclone in benzene under reflux. 

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). 

For cyclic olefins, compounds possessing structure (B) with a carbon-carbon double bond parallel to one of the M —M bonds are formed. Ruthenium carbonyls in analogous reactions give both (A) and (B) forms, as does Os3(CO)i2 in the reaction... 

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 mononuclear metal carbonyls contain only one metal atom, and they have comparatively simple structures. For example, nickel tetracarbonyl is tetrahedral. The pentacarbonyls of iron, ruthenium, and osmium are trigonal bipyramidal, whereas the hexacarbonyls of vanadium, chromium, molybdenum, and tungsten are octahedral. These structures are shown in Figure 21.1. 

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