Ruthenium structure

C NMR spectra, 29 188-189 structures, 29 207-208, 218 with copper, 29 202, 204, 206 fluxionality, 29 226 with manganese, 29 210 mass spectra, 29 190 MO calculations, 29 197 with molybdenum, 29 189 with nickel, 29 176, 179 reaction with phosphines, 29 229 structures, 29 210, 215, 221-222 photoelectron spectra, 29 193 with ruthenium structure, 29 218 synthesis, 29 229-230 structures, 29 210, 213-214 with tungsten, 29 189... 

The spherical dendrimer 62 serves as example of the metal-linked type. While both the central core (incorporating twelve terpyridine sites) and the terpyridine-containing components on the periphery of the structure are obtained by conventional organic synthesis, the overall dodeca-ruthenium structure assembles in 75% yield on reaction of the core with 15 equivalents of the 1 1 rathenium(III) chloride complex of the terminating terpyridyl derivative. 

Ruthenium and osmium have no oxides comparable to those of iron and, indeed, the lowest oxidation state in which they form oxides is -t-4. RUO2 is a blue to black solid, obtained by direct action of the elements at 1000°C, and has the rutile (p. 961) structure. The intense colour has been suggested as arising from the presence of small amounts of Ru in another oxidation state, possibly - -3. 0s02 is a yellowish-brown solid, usually prepared by heating the metal at 650°C in NO. It, too, has the rutile structure. 

Ruthenium and osmium form only disulfides. These have the pyrite structure and are diamagnetic semiconductors this implies that they contain M . RuSc2, RuTc2, OsSc2 and OsTc2 are very similar. All 6 dichalcogenides are obtained directly from the elements. 

If saturation occurs first, the product will be relatively stable toward further reduction but if hydrogenolysis occurs first, the resulting olefin is readily reduced. This ratio depends greatly on substrate structure, the catalyst, and environment. Hydrogenolysis is best achieved over platinum, whereas palladium (77a,82a,122bJ62a), rhodium (I09a), or ruthenium (I0a,I09a) tend to favor olefin saturation. 

Black-brown RuBr3 has roughly octahedral coordination of ruthenium (Ru-Br 2.46-2.54 A) with short Ru-Ru contacts (2.73 A) [17]. Black Rul3 has a similar structure. Neither is particularly soluble in water. 

It has a VF4 type puckered sheet structure with 6-coordinated ruthenium four fluorines bridge, two non-bridging ones are trans with the terminal distances shorter as expected (Table 1.1). It is paramagnetic (/xeff = 3.04/xB at room temperature). 

The complexes of ruthenium and osmium in the same oxidation state are generally similar and are, therefore, treated together the structural (Table 1.3) and vibrational data (Table 1.4) have been set out in some detail to demonstrate halogen-dependent trends. 

Ru02 can be made by high-temperature oxidation of ruthenium. It has the rutile structure (Ru—O 1.942 A and 1.984 A) and forms blue-black crystals [49b]. 

Figure 1.16 The structure of [Ru302(NH3) 4]6+, Ruthenium red. (Reprinted from Biochim. Bio-phys. Acta, 627, 332, 1980, with kind permission of Elsevier Science - NL, Sara Burgerhartstraat 25, 1055 KV Amsterdam, The Netherlands.)...

Figure 1.34 The structure of trinuclear oxo-centred ruthenium carboxylates. For clarity, only one of each pair of bridging carboxylates is shown.

Table 1.9 summarizes structural data for a number of ruthenium nitrosyl complexes, along with IR data [121, 122],... 

Table 1.9 Ruthenium nitrosyl complexes structural and IR data ...

Structural data on ruthenium porphyrins shows that the Ru-N (porphyrin) distance is relatively unaffected by changing the oxidation state, as expected for a metal atom inside a fairly rigid macrocyclic ring (Table 1.11). 

A considerable number of EDTA complexes of ruthenium have been synthesized [130-132] there has been interest in their catalytic potential while several compounds have had their structures determined. Synthetic routes relating to these compounds are shown in Figure 1.50. 

In all the compounds of known structure, ruthenium is 6-coordinate therefore, in complexes like Ru(EDTAH)(H20) [131], the acid is penta-dentate, with a free carboxylate group likewise, in K[Ru(EDTAH2)C12] and [Ru(EDTAH2)(dppm)] two of the carboxylates are protonated, so it is tetradentate. 

The structure of the aqua complex (Figure 1.51), which is an active intermediate in some catalytic systems, shows the Ru-OH2 distance to be some 0.1 A longer than in the ruthenium(III) hexaqua ion, indicating a possible reason for its lability the water molecule also lies in a fairly exposed position, away from the bulk of the EDTA group. 

The structures of both these complexes, typical of ruthenium(III) nitriles, were confirmed by X-ray diffraction ruthenium(II) nitriles are also possible ... 

Both of these elements are silver-white lustrous metals with high melting (ruthenium 2310°C, osmium 3900°C) and boiling (3900 and 5510°C, respectively) points. As usual, the 5d metal is much more dense (ruthenium 12.45, osmium 22.59gem-3) both adopt hep structures osmium is the densest metal known. The metals are unreactive, insoluble in all acids, even aqua regia. Ruthenium tends to form a protective coating of the dioxide and is not attacked by oxygen below 600°C nor by chlorine or fluorine below... 

The a-form has the a-TiCl3 structure with 6-coordinate ruthenium and a rather long Ru-Ru distance (3.46A) compared with the /3-form where... 

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