Ruthenium trichloride, in preparation

The dichlororuthenium arene dimers are conveniently prepared by refluxing ethanolic ruthenium trichloride in the appropriate cyclohexadiene [19]. The di-chloro(pentamethylcyclopentadienyl) rhodium dimer is prepared by refluxing Dewar benzene and rhodium trichloride, whilst the dichloro(pentamethylcyclo-pentadienyl)iridium dimer is prepared by reaction of the cyclopentadiene with iridium trichloride [20]. Alternatively, the complexes can be purchased from most precious-metal suppliers. It should be noted that these ruthenium, rhodium and iridium arenes are all fine, dusty, solids and are potential respiratory sensitizers. Hence, the materials should be handled with great care, especially when weighing or charging operations are being carried out. Appropriate protective clothing and air extraction facilities should be used at all times. 

Ruthenocene has been prepared in 20% yields by reaction of cyclopentadienylmagnesium bromide with ruthenium(III) acetyl-acetonate.8 More recently,4 the compound has been made in 43-52% yield by treatment of sodium cyclopentadienide with ruthenium trichloride in tetrahydrofuran or 1,2-dimethoxyethane. 

Ruthenium Tri-iodide, RuU, was prepared by Claus4 by double decomposition of potassium iodide and ruthenium trichloride in aqueous solution.5 The salt separates out as a black amorphous precipitate which, on heating, evolves the whole of its iodine content. It absorbs ammonia, welding 2RuIs.7NH3, but does not appear to yield double salts with alkali iodides.5... 

Cycloolefin-ruthenium complexes containing only olefins as ligands are normally difficult to prepare, and the yields are often very low. The classical methods involve Grignard reagents and UV irradiation or Ziegler catalysts.1 The direct reaction of cycloolefins with hydrated ruthenium trichloride in the presence of metallic zinc offers a versatile and very useful reaction for the preparation of cycloolefin-ruthenium (0) and -ruthenium (II) complexes.2... 

Unsymmetrically substituted ruthenocenes may also be prepared using gas-phase electrocyclic reactions of penta-dienylruthenium complexes. The precursor compounds are obtained by zinc reduction of either ruthenium trichloride in the presence of 5,5-dimethylcyclohexadiene to give bis(6,6-dimethylcyclohexadienyl)ruthenium or Cp RuClala in the presence of 2,4-di-/l r -butyl-l,3-pentadiene to give (pentamethylcyclopentadienyl)(2,4-di-/ r7-butylpentadienyl)ruthenium or dimethylcyclohexadiene to give (pentamethylcyclopentadienyl)(6,6-dimethylcyclo-hexadienyl)ruthenium. Sublimation of these compounds at 400-450 °C afforded the ruthenocenes 6-8. ... 

Dodecacarbonyltriruthenium can be prepared by several methods. Johnson and Lewis1 have reported a procedure in which ruthenium trichloride hydrate is converted to tris(2,4-pentanedionato)ruthenium(III), which is turn is reacted with hydrogen and carbon monoxide. Reaction pressure and temperature are high (160 atm and 165 °C) and the yield is in the range from 50 to 55%. 

The most widely used method for the preparation of 1,3,2-dioxathiolane. Y-oxides (cyclic sulfites) 65 bearing C-linked substituents is the reaction of the corresponding 1,2-diols with thionyl chloride in presence of pyridine or Et3N (Scheme 18). More reactive 1,3,2-dioxathiolane. Y,.Y-dioxidcs (cyclic sulfates) 66 are usually obtained by oxidation of sulfites 65 with sodium periodate, which is mediated by mthenium tetroxide generated in situ from a catalytic amount of ruthenium trichloride. Numerous derivatives 65 and 66 were obtained via this approach and its modifications for further transformations, mostly as the synthetic equivalents of epoxides <1997AHC89, 2000T7051> (see also Sections 6.05.5 and 6.05.6, and Tables 1-7). 

In 1971, a preparation of 1 from 2 using thallium cyclopentadienide was reported (I) but the toxicity of thallium and the mass of the reagent needed render this procedure unsuitable for large-scale preparations. An improved method was reported by Bruce et al. (3,4), using cyclopentadiene, ruthenium trichloride hydrate (3), and triphenylphosphine, which gives the desired complex in high yield [Eq. (2)]. The primary advantage of this latter method is formation of the complex in one pot. 

The best method of preparing pentamethylcyclopentadienyl arene ruthenium complexes is that of Kaganovich etal. (89). Three complexes of type 125 have been prepared in good yield directly from the commercial reagent ruthenium trichloride, pentamethylcyclopentadiene, and arenes (89). 

The early preparations gave poor yields but highly efficient methods have been developed recently. Optimum yields are obtained by the method of Pino and his coworkers9 in which tris(2,4-pentanedionato)ruthenium(III) is treated with equimolar mixtures of hydrogen and carbon monoxide at moderate temperatures and pressures (140-160°, 200-300 atmospheres). However, this method is limited by the availability of the tris-(2,4-pentanedionato)ruthenium(III) which is obtained in only low yields from the readily available ruthenium trichloride hydrate. The method given here is a modification on the Pino method. 

Ruthenium trichloride hydrate (5 g.), sodium acetylacetonate (7 g.), and methyl alcohol (140 ml.) are placed in the autoclave in that order. Hydrogen (40 atmospheres) and carbon monoxide (120 atmospheres) (i.e., total initial pressures = 160 atmospheres at room temperature) are then added and the reaction mixture heated at 165° for 4 hours. When cold the pressure is released and the crude orange crystalline dodecacarbonyltriruthenium separated by filtration. The mother liquor is evaporated to dryness and any additional product extracted into hot hexane in a Soxhlet apparatus. The combined products are then recrystallized from hot hexane, f Yields vary slightly from preparation to preparation but are usually in the range 50-55% (2.5 g.). (The checker obtained a yield of 3.0 g., 70%.)... 

The preparation of the hexaammine complexes of ruthenium(II) and ruthenium (III) salts are sketchily described in the literature. The preparation of hexaammineruthenium(II) by the reduction of ruthenium trichloride with zinc in ammonia is described briefly by Lever and Powell.1 Allen and Senoff2 carry out the reduction using hydrazine hydrate. The hexaammineruthe-nium(III) cation is obtained by oxidation of the ruthenium(II) complex,1 and pentaamminechlororuthenium(III) dichloride is obtained by treating the former compound with hydrochloric acid.1,3 This compound may also be obtained by treating the pentaammine molecular nitrogen complex of ruthenium(II) with hydrochloric acid.2,4... 

Potassium ruthenate, K2RUO4, is prepared in situ from ruthenium trichloride and aqueous persulfate. The reagent catalyzes persulfate oxidations of primary alcohols to acids, secondary to ketones, and primary amines to nitriles or acids at room temperature in high yields [196],... 

High yields of ketones result from the gentle oxidation of alcohols with compounds of ruthenium. Ruthenium tetroxide oxidizes cyclohexanol to cyclohexanone in carbon tetrachloride at room temperature in 93% yield [940], Instead of the rather expensive ruthenium tetroxide, which is required in stoichiometric amounts, catalytic amounts of ruthenium trichloride may be used in the presence of sodium hypochlorite as a reoxidant with the same results [701]. Sodium ruthenate [937] and potassium ruth-enate [196], which are prepared from ruthenium dioxide and sodium periodate in sodium hydroxide and from ruthenium trichloride and potassium persulfate, respectively, also effect oxidations to ketones at room temperature. 

The unusual oxidant nickel peroxide converts aromatic aldehydes into carboxylic acids at 30-60 °C after 1.5-3 h in 58-100% yields [934. The oxidation of aldehydes to acids by pure ruthenium tetroxide results in very low yields [940. On the contrary, potassium ruthenate, prepared in situ from ruthenium trichloride and potassium persulfate in water and used in catalytic amounts, leads to a 99% yield of m-nitrobenzoic acid at room temperature after 2 h. Another oxidant, iodosobenzene in the presence of tris(triphenylphosphine)ruthenium dichloride, converts benzaldehyde into benzoic acid in 96% yield at room temperature [785]. The same reaction with a 91% yield is accomplished by treatment of benzaldehyde with osmium tetroxide as a catalyst and cumene hydroperoxide as a reoxidant [1163]. 

Although the title complex was originally prepared by the reaction of ruthenium trichloride with triphenylphosphine in basic alcohol solution, it can also be prepared conveniently in higher yield by the following procedure. 

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