Iridium trichloride, reactions

Synthesis. The principal starting material for synthesis of iridium compounds is iridium trichloride hydrate [14996-61-3], IrCl3-a H2 0. Another useful material for laboratory-scale reactions is [Ir20l2(cod)2] [12112-67-3]. 

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. 

Iridium Trichloride, IrCl3, is most conveniently prepared2 by heating the reduced metal—obtained by precipitation from an alkali chloriridate solution with magnesium—with sodium chloride in a current of chlorine at 600° to 620° C. The reaction is complete in a few minutes. The limits of stability of the salt under these conditions lie from below 100° C. up to 763° C. Above this latter temperature it dissociates in an atmosphere of chlorine into iridium dichloride and chlorine, and at still higher temperatures (773° C.) into the monochloride. 

Iridium trichloride hydrate (2.00 g, 5.67 mmol based on IrCl3.3H20), sodium bicarbonate (2.00 g, 23.8 mmol, 4.2equiv.), and acetylacetone (2,4-pentane-dione, 20 mL, 196 mmol, 35equiv.) are loaded into a 50-mL round-bottomed flask equipped with a magnetic stir bar and a water-cooled reflux condenser. The reaction mixture is refluxed for 48 h (acetylacetone bp 140°C) under argon (the reaction can also be carried out under air with an oil bubbler attached to the condenser). The reaction mixture is then cooled to room temperature and diluted with 25 mL of dichloromethane to precipitate a yellow solid, which is filtered with a sintered glass filter frit. Often, the yellow solid adheres to the walls of the flask,... 

Ir(CO)2l3(COMe)], leading to [Ir(CO)2l2] and HI, but a route via the neutral [Ir(CO)2l2(COMe)] is also feasible (halide loss being known to facilitate other elimination reactions of Ir(lll) complexes ). Quantitative kinetic data have been reported for reductive elimination of MeCOCl from the analogous iridium trichloride, [Ir(CO)2Cl3(COMe)], as well as the reverse oxidative addition of MeCOCl to [Ir(CO)2Cl2] . " ... 

When ruthenium(III) chloride is heated in an atmosphere of carbon monoxide at 65 atmospheres, [Ru3(CO)i2l forms." Reduction of hydrated iridium trichloride by CO has been reported by Balch and coworkers. 8 mixture of the iridium salt and LiCl in 2-methoxyethanol was reacted with CO under pressure at 170 °C forming Li[IrCl2(CO)2]- When a toluene solution of l,3-bis(diphenylphosphino)propane was added to the reaction medium. 

Reactions with propene and allyl alcohol occur in a similar way. Analogous complexes containing cycloheptene, cyclooctene, 1,5-COD, norbornene, and norbornadiene are also formed from rhodium trichloride in aqueous ethyl alcohol however, the reaction stoichiometry for these olefins was not established. It is possible that the oxidation of alcohol occurs. For the preparation of rhodium and iridium complexes with cycloolefins of the formula [M2Cl2(olefin)4], the best results are obtained if aqueous ethyl or isopropyl alcohol is used as the solvent ... 

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