Ruthenium chemistry

Potzel et al. [Ill] have established recoil-free nuclear resonance in another ruthenium nuclide, ° Ru. This isotope, however, is much less profitable than Ru for ruthenium chemistry because of the very small resonance effect as a consequence of the high transition energy (127.2 keV) and the much broader line width (about 30 times broader than the Ru line). The relevant nuclear properties of both ruthenium isotopes are listed in Table 7.1 (end of the book). The decay... 

Clarke, M. J. Ruthenium Chemistry Pertaining to the Design of Anticancer Agents Progress in Clinical Biochemistry and Medicine Springer-Verlag Berlin, 1989 Vol. 10, pp 25-40. 

The current research areas with ruthenium chemistry include the effective asymmetric hydrogenation of other substrates such as imines and epoxides, the synthesis of more chemoselective and enantioselective catalysts, COz hydrogenation and utilization, new methods for recovering and recycling homogeneous catalysts, new solvent systems, catalysis in two or three phases, and the replace-... 

The iodide promoter effects seen in Fig. 20, and some of the catalyst behavior to be described below, can be partially understood in terms of the ruthenium chemistry involved. Iodide salts have been found (191) to react... 

An excellent comprehensive review of ruthenium chemistry is E. A. Seddon and K. R. Seddon, The Chemisty of Ruthenium, Elsevier Science Publishing Co., Inc., New York, 1984. 

The first reported examples of M6C carbidocarbonyl clusters were originally found in ruthenium chemistry. Ru6C(CO),7,16, and itsarene derivi-ties RueQCO) (arene) (arene = toluene, xylene, and mesitylene) (36, 37) were synthesized in modest yields by refluxing Ru3(CO)l2 in the requisite arene, 16 becoming the major product when a saturated hydrocarbon such as decane was the solvent. 

The development of ruthenium complexes for other applications in radical chemistry is still in its infancy, but seems well suited to future expansion, thanks to the versatility of ruthenium as a catalytically active center. Large avenues have not been explored yet and remain open to research. For instance, the development of methodologies for the asymmetric functionalization of C-H bonds remains a challenge. The Kharasch-Sosnovsky reaction [51,52],in which the allylic carbon of an alkene is acyloxylated, its asymmetric counterpart, and the asymmetric version of the Kharasch reaction itself are practically terra incognita to ruthenium chemistry, and await the discovery of improved catalysts. 

Ruthenium complexes with N ligands are extremely numerous, forming perhaps the most extensive and important areas of ruthenium chemistry, especially in oxidation states II and III. 

In common with other platinum metals, an important area of ruthenium chemistry involves trialkyl- and triarylphosphines, and the corresponding phosphites. An extremely wide range of complexes is known, mainly of the II state, although compounds in the 0, III, and less commonly, IV state are known other ligands commonly associated with the PR3 group are halogens, alkyl and aryl groups, CO, NO, and alkenes as well as H and H2. Similar chemistry is found for osmium. 

Ruthenium and, particularly, osmium form a great many high nuclearity carbonyl clusters. Only a few illustrative examples can be mentioned here. Figure 18-F-6 shows some of the topological relationships among the osmium compounds. The scope of the ruthenium chemistry has been extended recently with the preparation of the [RuioH2(CO)25]2 and [RunH(CO)27]3 ions.137... 

We have previously mentioned in Section 4.2 the chemistry developed by Selhnann etal, by using tetradentate or pentadentate S4 ligands. The use of such a ligand in nitrosyl ruthenium chemistry allowed the first conversion of a nitrosyl complex into a ruthenium HNO complex (31) by addition of NaBILi to [Ru(NO)(py S4)]Br. The formation and decomposition of HNO complexes is often invoked in many processes such as combustion of ftiels, oxidation of N2, reduction of HNO2, and so on. ... 

Ruthenium polyhydride complexes containing monophos-phaferrocenes are now available. In contrast to Cp ruthenium chemistry, the use of a trispyrazolyborate ligand favors the formation of dihydrogen structures the chemistry of Tp... 

Hydrogen bonding is a well-known phenomenon that has led to major developments during the last decade in the field of polyhydrides. The formation of the so-called dihydrogen bond (M H- H X) can occur intermolecularly between a hydride and a weak acid (see equation 4) or intramolecularly between a hydride and a pendant ligand with an NH or OH group. This type of interaction is very important as it may control reactivity and selectivity in solution. A few examples have appeared in ruthenium chemistry. 28... 

One of the most prominent features of ruthenium chemistry is that the metal forms numerous compounds containing the (RuNO) + fragment. Furthermore, the metal-nitrosyl fragment has in general been of interest to many because of the potential 7r-acceptor ability of NO and its possible existence as NO+, NO , or NO. Explicit details of how to synthesize the ruthenium-NO complexes are virtually nonexistent, and procedures, when available, are laborious. Here we give the preparative descriptions for such compounds by newly developed methods which are explicit and convenient. The information is also valuable in view of the cost of ruthenium. 

Orthometallation of triarylphosphine and triarylphosphite at mthenium has long been knovm as intramolecular C-H bond activation in ruthenium chemistry [2], but did not receive attention from organic chemists. In 1965, Chatt and Davidson documented that a Ru(0) complex, which was formed by two-electron reduction of Ru(II) by use of sodium naphthalene is capable of reversible cleavage of sp C-H bonds of naphthalene by oxidative addition/reductive elimination processes (Scheme 14.1) [3]. 

This work provides a relatively comprehensive review of studies involving ruthenium coordination and organometallic complexes as nonlinear optical (NLO) compounds/materials, including both quadratic (second-order) and cubic (third-order) effects, as well as dipolar and octupolar chromophores. Such complexes can display very large molecular NLO responses, as characterised by hyperpolarizabilities, and bulk effects such as second harmonic generation have also been observed in some instances. The great diversity of ruthenium chemistry provides an unparalleled variety of chromophoric structures, and facile Ru" —> Ru" redox processes can allow reversible and very effective switching of both quadratic and cubic NLO effects... 

One of the most interesting recent topics in ruthenium chemistry is undoubted ) C—H bond activation in which the generation of coordinatively unsaturated specie> may play an important role. These species are usually produced by thermal or photo-mediated reductive elimination of dihydrogen, alkanes, alkenes or arenes. Recently, dehydrochlorination from RuHCI(CO) (P BuTMe) is reported to give a 7C-allyl complex via C—H activation of propylene (eq (42)) [144]. 

A final example from ruthenium chemistry concerns the hydrogenation of butadiene-2,3-dicarboxyhc acid, where it is clear that the second double bond reduction is influenced by the stereochemical course of the first hydrogenation [72]. The half-reduced intermediate is of S-conflguration when the racemic mo-noene is hydrogenated under identical conditions the reaction is neither enan-tio- nor diastereoselective. 

Ruthenium Nitrosyls. These nitrosyls are more numerous than those of any other element and are, in fact, a dominant feature of ruthenium chemistry (see Section 26-F-5). 

The formation of nitric oxide complexes is a marked feature of ruthenium chemistry those of Os have been less well studied, but where known they are even more stable than the Ru analogs. 

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