Chloro ruthenium complexes

Ruthenium Chloro Complexes. Fig, 26-F-l gives some common reactions of these chloro species. 

Ruthenium chloro-complexes have been separated by electrophoresis. ° RuCl3, prepared as a fission isotope from U, exchanged the ruthenium atom with the cobalt of Co "(acac)3 in the solid state. The yield of Ru (acac>3 was consistent with first-order kinetics for the exchange process. If the cobalt remained correlated with the ruthenium after exchange, then slow cooling to a lower temperature should decrease the yield of Ru (acac>3 this did not occur, and the yield of exchanged product may depend on the relative strengths of the Ru—O and Co—O bonds in the acetylacetone complexes. 

Ruthenium(m).—Group VII Donors. The consecutive stability constants Ky—Kj of chloro-complexes of Ru have been determined in aqueous and aqueous-alcoholic 1N-HC104. Other Russian workers have compared the... 

Chloro complexes of ruthenium(II) were found to hydrogenate maleic and fumaric adds to succinic add slowly at 60-80 °C and normal pressure of hydrogen. Non-activated alkenes lead to the production of ruthenium metal. The structures of the species involved are unknown. The mechanism involves coordination of the alkene followed by heterolytic cleavage of hydrogen, giving a ruthenium(II) hydride as the second step.41... 

From a practical standpoint, it is of interest to devise a one-step synthesis of the catalyst. Since both reactions 2 and 3 are ligand substitution reactions, it is quite conceivable that both steps can be carried out at the same time. When we reacted [Ru(COD)Cl2]n with BINAP and sodium acetate in acetic acid, we indeed obtained Ru(BINAP)(OAc)2 in good yields (70-80%). Interestingly, when the reaction was carried out in the absence of sodium acetate, no Ru(BINAP)(OAe)2 was obtained. The product was a mixture of chloro-ruthenium-BINAP complexes. A 3ip NMR study revealed that the mixture contained a major species (3) (31P [ H] (CDCI3) Pi=70.9 ppm P2=58.3 ppm J = 52.5 Hz) which accounted for more than 50% of the ruthenium-phosphine complexes (Figure 2). These complexes appeared to be different from previously characterized and published Ru(BINAP) species (12,13). More interestingly, these mixed complexes were found to catalyze the asymmetric hydrogenation of 2-(6 -methoxy-2 -naphthyl)acrylic acid with excellent rates and enantioselectivities. 

Ruthenium(III) chloride (2.0 g., 9 mmoles) (free from nitrosyl impurities) is dissolved in water (10 ml.) in a 200-ml. beaker. Hydrazine hydrate (85%, 20 ml.) is added carefully to the well-stirred solution. The initial reaction is exothermic, and large quantities of gas are evolved. The solution is stirred for about 12 hours and filtered by gravity. Because of the vigorous evolution of gas and the highly exothermic nature of the initial reaction, it is not recommended that the scale of the reaction be increased. Chloro complexes such as (NH<)2[RuClt] or K2[RuC15H20] may be substituted for ruthenium (III) chloride. 

Christian and Roper (57) have isolated white crystals of a six-coordinate ruthenium(II) complex, fmns-RuH(C0)(p-tNC)(Ph3P)20C103 by treating the corresponding chloro complex with AgC104 in EtOH. The coordinated perchlorate can be readily displaced by CO or Ph3P. 

A few cyano phosphine and arsine complexes of ruthenium(II) have been reported. These include tra s-[RuH(CN)(dmpe)2] (dmpe = Me2P(CH2)2PMe2) obtained from the corresponding chloro complex and aqueous KCN43 or more recently by treatment of [RuH(2-np)(dmpe)2] (2-np = 2-naphthyl) with HCN. The latter gives a 85% cis, 15% trans isomer mixture ( H NMR evidence).44... 

Ruthenium(JI) chloro complexes, whose precise nature is still uncertain, are obtained when RuCl3 H20 in HC1 solution is reduced electrochemically or chemically using ethanol or H2/Pt black. Deep blue, very air-sensitive solutions can... 

Ruthenium(IV) chloro complexes with OH and H20 ligands can be obtained, but the [RuQ6]2- ion is formed only in high concentrations of Q by chlorine oxidation of Rum chloro complexes. The purple or brown salts are isomorphous with other [MCI ]2- species of Os, Ir, Pd, and Pt. 

Ruthenium chloride complexes, such as dichlorotris(triphenylphosphane)ruthenium(II), effectively catalyze the addition of polyhalocarbons to double bonds5 13 18. In a mechanistic and stereochemical study, carbohalogenation of cyclohexene with carbon tetrachloride in the presence of dichlorotris(triphenyIphosphane)rulhenium(II) gave l-chloro-2-(trichloromethyl)cyclohexane (2) in 77% yield and a diastereomeric ratio (transjeis) of 96 419. In comparison, the same conversion promoted by dibenzoyl peroxide is considerably less selective and gives the same product in only 10% yield with a 53 47 ratio of the trans, cis-isomets. This striking difference led to the conclusion that the ruthenium-catalyzed version does not proceed via a free-radical mechanism, as assumed in the peroxide-mediated reaction. 

Ruthenium Red. A characteristic of ruthenium complex ammine chemistry is the formation of highly colored red or brown species usually referred to as ruthenium reds. Thus, if commercial ruthenium chloride is treated with ammonia in air for several days, a red solution is obtained. Alternatively, if Ru111 chloro complexes are reduced by refluxing ethanol and the resulting solution is treated with ammonia and exposed to air at 90° with addition of more ammonia at intervals, again a red solution is obtained. Crystallization of the solutions gives ruthenium red. 

Among the few known heteroruthenocenes are cationic thiophene- and bis(thiophene)ruthenium, electronic analogs to arene ruthenium sandwich complexes (Section 5), and derivatives featuring a tetramethylpyrrole (tp) ligand, Cp Ru(tp) (91) and Ru(tp)2, prepared by an adaptation of the Zn reduction method to the chloro complex [Cp RuCl2]2 (92) (equation 21). The methyl groups are necessary to prevent a-complexation of the pyrrole ligand however, under suitable conditions ([Cp Ru(acac)]2/Zn +/pyrrole in ether), the preparation of at least Cp Ru (pyrrole) (93) has been equally successful (equation 22). 

Hybrid catalysts derived from cocondensation of Group 8 metal-chloro complexes with Si(OEt)4 via a sol-gel process were highly active for the synthesis of A/,iV-dimethyIformamide from CO2, H2 and dimethylamine under supercritical conditions, affording turnover numbers up to 100800 at 100% selectivity [61]. The activity of the catalysts, containing methylphosphine ligands, decreased in the order Ru>Ir>Pt,Pd>Rh. It seemed that the high activity of silica matrix stabilized ruthenium complexes was due to the formation of an active hydride intermediate by hydrogenolysis of the Ru-Cl bond. 

The complex ion [Ru(bpy)(trpy)Cl] was first prepared as the perchlorate salt by the reaction of Ru(bpy)Cl4 with trpy in 25% aqueous ethanol, and more recently in 75% aqueous ethanol. It has also been prepared from Ru(CO)2(bpy)Cl2, trpy, and trimethylamine oxide in 2-methoxyethanol. A method in which the readily prepared RuftrpylClj complex is used as an intermediate is more convenient, and it is this new method that is described here. (2,2 -Bipyridine-A(,A( )chloro(2,2 6, 2"-terpyridine-Al,Al, N")osmium(II) chloride has been reported and is prepared from Os(bpy)Cl4" and trpy in ethylene glycol. (2,2 -Bipyridine-N,Al )chloro 2,2 6, 2"-terpyridine-Al,N, yV")osmium(II) chloride may also be prepared by the reaction of Os(trpy)Cl3 with bpy in ethylene glycol. However, the insolubility of Os(trpy)Cl3 in this solvent makes the procedure used for the ruthenium analog less desirable, and the literature method has been used without major modification. Reaction of the chloro complexes With hot... 

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