Ru and

A variety of [RuH(cod)L ] complexes (L = phosphorus donor) undergo irreversible conversion on heating to the En -cyclooctenyl)RuL ] derivative, the ease increasing with the 

CMe )(BPh.) characterized crystallographically as having trans-hydrazone ligands. 

Kinetic studies of the displacement of diene from (diene)M(CO)  

Fe(C2H )2 and Fe2(C2H )2 Though the latter two are typical ir-complexes, Fe(C2H ) exists as two isomeric forms in which iron is bound via the hydrogen atoms photoexcitation results in reversible photoinsertion to give HPeC2H2. A similar structure 

CpRu(n -allyl)X2 (X=Cl,Br) with MeLi gives CpRu(n -allyl)(X)Me 

CpRh(n -allyDCl provides a route to substituted rhodicenium salts.Acidolysis of OsH(n -2-methylallyl) (PPh ) 2 the presence of CO yields [OsH(CO)2(OH2)(PPh )2]characterized crystallographically. 

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A few illustrative examples are the following. Photohydrogenation of acetylene and ethylene occurs on irradiation of Ti02 exposed to the gases, but only if TiOH surface groups are present as a source of hydrogen [319]. The pho-toinduced conversion of CO2 to CH4 in the presence of Ru and Os colloids has been reported [320]. Platinized Ti02 powder shows, in the presence of water, photochemical oxidation of hydrocarbons [321,322]. Some of the postulated reactions are ... 

The residue, which contains Ir, Ru, and Os, is fused with sodium peroxide at 500°C, forming soluble sodium mthenate and sodium osmate. Reaction of these salts with chlorine produces volatile tetroxides, which are separated from the reaction medium by distillation and absorbed into hydrochloric acid. The osmium can then be separated from the mthenium by boiling the chloride solution with nitric acid. Osmium forms volatile osmium tetroxide mthenium remains in solution. Ruthenium and osmium can thus be separately purified and reduced to give the metals. 

Ruthenium and osmium are generally found in the metallic state along with the other platinum metals and the coinage metals. The major source of the platinum metals are the nickel-copper sulfide ores found in South Africa and Sudbury (Canada), and in the river sands of the Urals in Russia. They are rare elements, ruthenium particularly so, their estimated abundances in the earth s crustal rocks being but O.OOOl (Ru) and 0.005 (Os) ppm. However, as in Group 7, there is a marked contrast between the abundances of the two heavier elements and that of the first. 

Ru and Os, along with Ir, are regarded as the minor platinum metals, being obtained largely as byproducts in the production of Pt, Pd and Rh, and their annual world production is only of the order of tonnes. (Weights of Ru and Os, as of most precious metals, are generally quoted in troy ounces 1 troy ounce = 1.097 avoirdupois ounce = 31.103 g.)... 

Table 25.1 summarizes some of the important properties of Fe, Ru and Os. The two heavier elements in particular have several naturally occurring isotopes, and difficulties in obtaining calibrated measurements of their... 

Figure 25.2 Plot of volt-equivalent against oxidation state for Fe, Ru and Os in acidic aqueous solution.

The most interesting oxides of Ru and Os, however, are the volatile, yellow tetroxides, RUO4 (mp 25°C, bp 130°C< 3>) and OSO4 (mp 40°C, bp 130°C). They are tetrahedral molecules and the latter is perhaps the best-known compound of osmium. It is produced by aerial oxidation of the heated metal or by oxidizing other compounds of osmium with... 

By heating the metal with appropriate oxides or carbonates of alkali or alkaline earth metals, a number of mixed oxides of Ru and Os have been made. They include NasOs Og, LifiOs Og and the ruthenites , M Ru 03, in all of which the metal is situated in octahedral sites of an oxide lattice. Ru (octahedral) has now also been established by Ru Mdssbauer spectroscopy as a common stable oxidation state in mixed oxides such as Na3Ru 04, Na4Ru2 07, and the ordered perovskite-type phases M Ln Ru Og. 

Figure 2S J Teiramenc pentafluondes of Ru and Os, Their structures are similar to, but more disloned than, those of the pentafloorides of F4b and Ta (see Fig. 22 4)...

Fluorides and 0x0 compounds of Ru and Os have already been mentioned, and salts such as (R4N)[Ru04l, (R = n-propyl, n-butyl) are useful reagents to oxidize a variety of organic materials without attacking double or allylic bonds,... 

Fe(CO)s is a highly toxic substance discovered in 1891, the only previously known metal carbonyl being Ni(CO)4. Like its thermally unstable Ru and Os analogues, its structure is trigonal bipyramidal (Fig. 25.10a) but its C nmr spectrum indicates that all 5 carbon atoms are equivalent and this is explained by the molecules fluxional behaviour (p. 914). 

This is also the case in the decamethylmetal-locenes of Ru and Os but not in the iron analogue which has a staggered conformation, presumably due to steric crowding around the smaller metal. 

The structures are shown in Fig. 26.8c and d and differ in that, whereas the Ir compound consists of a tetrahedron of metal atoms held together solely by M-M bonds, the Rh and Co compounds each incorporate 3 bridging carbonyls. A similar difference was noted in the case of the trinuclear carbonyls of Fe, Ru and Os (p. 1104) and can be explained in a similar way. The M4 tetrahedra of Co and Rh are small enough to be accommodated in an icosahedral array of CO ligands whereas the larger Ir4 tetrahedron forces the adoption of the less dense cube octahedral array of ligands. 

Triple-decker complexes with pentaphospholyl cycle between Ru and Fe or Ni atoms and carboranes and carbacycles C H (n = 4-7) as terminal ligands 99IZV1636. 

The formation of TMM complex from Group VIII transition metal such as Ir, Ru, and Os from precursors derived from (1) has been reported M.D. Jones, R. D.W. Kemmitt,/. Chem. Soc., Chem. Commun., 1985, 811-812. 

Alkylation lo yield a leriiary amine may occur easily if the formation involves cyclization (ii). Catalysts may have a marked influence. In reductive alkylation of ammonia wilh cyclohexanones, more primary amine was formed over Ru and Rh and more secondary amine over Pd and Pt. Reduction of the ketone to an alcohol is an important side reaction over ruthenium. 

The major fission products which will limit overall decontamination (other than from the lanthanides) are Tc, Ru, and Pd. formed to evaluate the actual decontaminations which can be achieved. 

Major limitations in fission product decontamination will require tests with mixer-settlers. However, we anticipate from the distribution ratio measurements that Tc, Ru, and Pd will limit the overall decontamination from beta activity (other than from lanthanides). ... 

In this discussion, two mutually canceling simplifications have been made. For the transition value of the radius ratio the phenomenon of double repulsion causes the inter-atomic distances in fluorite type crystals to be increased somewhat, so that R is equal to /3Rx-5, where i has a value of about 1.05 (found experimentally in strontium chloride). Double repulsion is not operative in rutile type crystals, for which R = i M + Rx- From these equations the transition ratio is found to be (4.80/5.04)- /3i — 1 = 0.73, for t = 1.05 that is, it is increased 12%. But Ru and Rx in these equations are not the crystal radii, which we have used above, but are the univalent crystal radii multiplied by the constant of Equation 13 with z placed equal to /2, for M++X2. Hence the univalent crystal radius ratio should be used instead of the crystal radius ratio, which is about 17% smaller (for strontium chloride). Because of its simpler nature the treatment in the text has been presented it is to be emphasized that the complete agreement with the theoretical transition ratio found in Table XVII is possibly to some extent accidental, for perturbing influences might cause the transition to occur for values a few per cent, higher or lower. 

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