Ruthenium complexes chlorides

The three steps 32-34 have been suggested77 to be equilibria, and the overall equilibrium must lie far to the left because no adduct 23 is found in the reaction mixture when the reaction of sulfonyl chloride with olefin is carried out in the absence of a tertiary amine. A second possible mechanism involving oxidative addition of the arenesulfonyl halide to form a ruthenium(IV) complex and subsequent reductive elimination of the ruthenium complex hydrochloride, [HRulvCl], was considered to be much less likely. 

Ruthenium complexes have also been reported as active species for enan-tioselective Diels-Alder reactions. Faller et al. prepared a catalyst by treatment of (-)-[( ] -cymene)RuCl(L)]SbF6 with AgSbFe resulting in the formation of a dication by chloride abstraction [95]. The ligand was (-l-)-IndaBOx 69 (Scheme 36) and the corresponding complex allowed the condensation of methacrolein with cyclopentadiene in 95% conversion and 91% ee. As another example, Davies [96] prepared the complex [Ru(Fl20)L ( i -mes)] [SbFe]2 (with 70 as L in Scheme 36), and tested its activity in the same reaction leading to the expected product with similar activity and lower enan-tioselectivity (70%). 

Denmark pursued intramolecular alkyne hydrosilylation in the context of generating stereodefined vinylsilanes for cross-coupling chemistry (Scheme 21). Cyclic siloxanes from platinum-catalyzed hydrosilylation were used in a coupling reaction, affording good yields with a variety of aryl iodides.84 The three steps are mutually compatible and can be carried out as a one-pot hydro-arylation of propargylic alcohols. The isomeric trans-exo-dig addition was also achieved. Despite the fact that many catalysts for terminal alkyne hydrosilylation react poorly with internal alkynes, the group found that ruthenium(n) chloride arene complexes—which provide complete selectivity for trans-... 

Ruthenium complexes are capable of catalyzing halogen atom transfer reactions to olefins. This has been illustrated in the enantioselective atom transfer reactions of alkane and arene-sulfonyl chlorides and bro-motrichloromethanes to olefins using chiral ruthenium complexes. Moderate ee s up to 40% can be achieved for these transformations [74-77]. These specific reactions are believed to follow a radical redox transfer chain process. 

The course of the condensation of ethylene glycol with secondary amines (Me2NH, Et2NH, pyrrolidine or morpholine) depends on the catalyst used. Triphenylphosphine complexes of ruthenium, e.g. RuCl2(PPh3)3, give hydroxyalkylamines while hydrated ruthenium(III) chloride yields diamines (equation 24)62. 

Hydride ion transfer from formic acid and its salts finds widespread application in the reduction of organic substrates, but limited use has been made of the procedure under phase-transfer catalytic conditions. However in the presence of a ruthenium complex catalyst, it is possible to selectively reduce the C=C bonds of conjugated ketones with sodium formate [11], The rate of reduction is fastest with tetrahexyl-ammonium hydrogensulphate and Aliquat the complete reduction of chalcone being effected within one hour, whereas with benzyltriethylammonium chloride only ca. 15% reduction is observed after two hours under similar conditions. 

To separate osmium from ruthenium, the aqueous solution is acidified with nitric acid. While nitric acid oxidizes osmate ion to volatile osmium tetroxide, Os04, it converts ruthenium to a nitric oxide complex. Osmium tetroxide is removed from the solution by distillation in air and collected in an aqueous solution of caustic soda containing ethanol. Osmium tetroxide solution is heated with ammonium chloride, upon which osmium precipitates out as a complex chloride, 0s02(NH3)4Cl2. The precipitate is filtered, washed and decomposed by ignition with hydrogen to yield osmium metal. 

The formation of other mono- [27-29] or even bis[alkoxy(alkenyl)allenylidene[ ruthenium complexes [28, 30] from the corresponding ruthenium chlorides and 5,5 -diphenyl-penta-1,3 -diynyl alcohol or trimethylsilyl ether in the presence of methanol (Scheme 3.13) and of the allenylidene complex 18 in the absence of methanol (Scheme 3.13) [30, 31] was also suggested to proceed via pentatetraenylidene intermediates. Neither one of these pentatetraenylidene complexes could be isolated or spectroscopically detected although their formation as an intermediate was very likely. 

Trust s group has shown that another selective reaction involving C—O bond formation followed by rearrangement and C—C bond formation occurred when Cp-containing ruthenium complexes were used as catalytic precursors. With RuCl(Cp)(PPh3)2 in the presence of NH4PF6, an additive known to facilitate chloride abstraction from the metal center, the addition of allylic alcohols to terminal alkynes afforded unsaturated ketones [46, 47]. It has been shown that the key steps are the... 

Dr. Halpern I don t know whether this is relevant to the first reaction or not, but we have also been struggling with the study of various reactions of ruthenium chlorides including ruthenium(II) chloride for a long time. Among the reactions studied is the formation of olefin and carbonyl complexes of ruthenium(II). These form readily in aqueous solution, and are fairly stable. James and Kemp, working on these systems in my laboratory have studied in some detail the kinetics of the reactions ... 

Primary amines at a primary carbon can be dehydrogenated to nitriles. The reaction has been carried out with a variety of reagents, among others, IF5,"9 lead tetraacetate, 20 nickel peroxide,121 NaOCl in micelles,122 S g-NiSO, 2-1 and CuCl-02-pyridine.124 Several methods have been reported for the dehydrogenation of secondary amines to imines.125 Among them126 are treatment with(l) iodosylbenzene PhIO alone or in the presence of a ruthenium complex, 27 (2) Me2SO and oxalyl chloride, 2" and (3) f-BuOOH and a rhenium catalyst. 29... 

Barbier reaction Samarium(II) iodide, 270 Benzoannelation Chromium carbene complexes, 82 Dicarbonylcyclopentadienylcobalt, 96 Ethyl (Z)-3-bromoacryIate, 130 Grignard reagents, 138 Methyl acrylate, 183 Methyllithium, 188 Ruthenium(III) chloride, 268 Benzoin condensation Benzyltriethylammonium chloride, 239 3-EthyIbenzothiazolium bromide, 130 Benzoylation (see also Acylation) Cadmium, 60 Dibutyltin oxide, 95 Birch reduction Birch reduction, 32... 

Anhydrous ruthenium(lll) chloride, RuCL, is made by direct chlorination of the metal at 700°C. Two aliotropic forms result. The trihydrate is made by evaporating an HQ solution of rulheinuiu(III) hydroxide to dryness or reducing ruthenium(VIII) oxide in a HQ solution. The tnhydrate, RuCk 3R>0, is the usual commercial form. Aqueous solutions of the tri-hydrate are a straw color in dilute solution and red-brown in concentrated solution. Ruthenium(lll) chloride in solution apparently forms a variety of aquo- and hydroxy complexes. The analogous bromide. RuBr3, is made by the same solution techniques as the chloride, using HBr instead of HQ. 

In N,N-dimethylacetamide solution the reduction by hydrogen of ruthenium(HI) chloride is claimed to produce ruthenium(I) complexes which hydrogenate ethylene, maleic and fumaric adds. The complexes are thought to be dimeric but their precise structures are unknown. Interestingly, these d1 ruthenium(I) complexes are believed to activate hydrogen by oxidative addition whereas heterolytic cleavage of hydrogen occurs with most ruthenium catalysts (equation 19). 

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