Iridium, chloride

Another reduction process, catalyzed by iridium chloride, is characterized by very high axiatiequatorial product ratios for cyclohexanones and apparently involves hydride transfer from isopropanol.197... 

In 1957 (2) platinic, ruthenium, and iridium chlorides were shown to be catalysts leading to very rapid additions, sometimes below room temperature, of many kinds of SiH compounds. These findings initiated much activity, chiefly in industrial research laboratories, in several countries, because they indicated that the manufacture of new organosilicon monomers and many new silicone polymers and copolymers would become commercially practicable for the first time. 

The secondary aryl amine 24 is far less basic than primary or secondary alkyl amines, and does not form the carbamic acid to any detectable extent in the presence of scC02 [31]. Therefore, 24 is extracted readily from the catalyst-containing IL phase, which can be recycled without noticeable loss of activity and selectivity [13]. In fact, it transpires that the active species is more stable towards oxygen in the IL than in organic solvents. Furthermore, the choice of anion of the IL largely controls the performance of the active cationic species, allowing even the use of an otherwise inactive iridium chloride precursor [ Ir(cod)Cl 2] to form in-situ catalysts... 

No complex was obtained on treatment of iridium (III) chloride with ethylene (67, 97, 138) or cyclo-octa-1,5-diene (45), but the ethylene complex [IrCl2(C2H4)] was reported to be formed by the action of ethanol on iridium chloride (67,138). No further examination of this complex has been reported. 

Hexammino-iridium Chloride, [Ir(NH3)e]Cl3, is prepared by heating chloro-pentammino-iridium chloride, [Ir(NH3)5Cl]CI2, with 25 per cent, aqueous ammonia in a sealed tube to 140° C. The crude product so obtained is evaporated with hydrochloric acid, the residue dissolved in water, and precipitated by means of sodium pyrophosphate. From this the nitrate is formed by treating with dilute hydrochloric and nitric acids, and finally the nitrate is decomposed by repeated evaporation to dryness with concentrated hydrochloric acid. The residue is then treated with ice-cold hydrochloric acid, when the chloride is precipitated. It crystallises in large six-sided colourless prisms belonging to the monoclinic system, and is soluble in water.1... 

Hexammino-iridium Chloro-iridite, [Ir(NHs)6][IrCl6], is precipitated as an amorphous yellow powder on the addition of potassium chloro-iridite to hexammino-iridium chloride. From dilute solution it crystallises in small quadratic plates. It is soluble in cold water, and fairly stable towards concentrated sulphuric acid, which only attacks it above 190° C. 

Chloro - pentammino - iridium Chloride, [Ir(NH3)sCl]Cl2, is formed by the action of ammonia on iridium trichloride, iridium tetrachloride, or the ehloro-double salts. It may also be prepared from chloro-pentammino-iridium sulphate by treating it with barium chloride. Prepared by the first method it separates in wine-coloured crystals, whilst by the second method it is yellow. The red colour of the first product is due to a small quantity of iridium trichloride, which separates with the chloro-ehloride and may be removed by heating the hot aqueous solution with hydrogen sulphide. It crystallises in 1 Jorgensen, J. prakt. Ghem., 1888, 34, 394 Palmaer, Ber., 1891, 24, 2090. 

Bromo - pentammino - iridium Bromide, [Ir(NH3)5Br]Br2, is prepared by boiling chloro-pentammino-iridium chloride with potassium hydroxide for five hours to form the hydroxide, and then adding excess of 50 per cent, hydrobromic acid. A white crystalline precipitate of aquo-pentammino-iridium bromide, [Ir(NH3)5H20]Br3, is obtained, and on heating a solution of this it is converted into the bromo-bromide. The salt separates in yellow rhombic prisms and is soluble in water.4... 

Nitrito-pentammino-iridium Chloride, [Ir(NH3)5N02]Cl2, may be produced by treating dinitrito-tetrammino-iridium chloride with ammonia, or, in better yield, by acting upon aquo-pentammino-iridium chloride with excess of silver nitrite. It separates from aqueous solution on addition of hydrochloric acid in small colourless needles which arc very soluble in water and sparingly soluble in hydrochloric acid. It is stable, and scarcely acted on by boiling nitric acid or aqua-regia or moderately strong hydrochloric acid. 

Dinitrito-tetrammino-iridium Chloride, [Ir(NH3)4(N02)2]Cl, is prepared by heating sodium iridio-tetranitrito diehloride, [IrCl2(N02)4]... 

Dichloro-tetrammino-iridium Chloride, [Ir(NH3)4Cl2]Cl.H20, is produced when dinitrito-tetrammino-iridium chloride is heated with ammonium chloride and concentrated hydrochloric acid for several hours. A yellow liquid is obtained, from which on evaporation a yellow crystalline precipitate separates containing the chloro-compound mixed with ammonium chloride. This is collected, dissolved in warm water, filtered, and allowed to crystallise on the addition of hydrochloric acid. It separates in yellow needles and prisms which are impure, but are purified on further reerystallisation from warm water containing acid. It loses water on heating, and finally leaves a residue of iridium. Concentrated hydrochloric acid does not attack the salt. 

A reactor was charged with 150 ml of 2-ethoxyethanol, 50 ml of water, and 2-phenyl-pyridine (58 mmol) and then treated with iridium chloride(III) trihydrate (28 mmol) and refluxed for 12 hours under nitrogen. The solution was slowly cooled to ambient temperature and a precipitate isolated, which was washed with methanol, dried, and... 

Iridium Arsenide, IrAs2, has been obtained in a pure form by heating iridium chloride with an excess of arsenic in a current of hydrogen.4 It is also formed when an intimate mixture of the finely divided metal and excess of arsenic is heated in an indifferent atmosphere. The arsenide may be analysed by the method described under palladium arsenide (p. 73). 

Iridium Arsenate is said14 to be precipitated when sodium orthoarsenate is added to a hot solution of iridium chloride. 

Iridium Tetra-iodide, Irl4, results when a solution of ammonium chloriridate or of iridium chloride in hydrochloric acid is boiled with potassium iodide.4 It is precipitated as a black, insoluble powder, which decomposes at 100° C. 

Potassium Iodiridate, K2IrI6, is formed when a solution of iridium chloride is added to one of potassium iodide. The solution is filtered, and the iodiridate obtained on crystallisation as dark brown octahedra.5... 

It is a black, colloidal substance, soluble in aqua regia, giving an iridium chloride, and decomposable at high temperatures, yielding metallic iridium. 

Ruthenium may be separated from all metals except osmium by distilling in alkaline solution in a current of chlorine at 70° C. The ruthenium distils over as tetroxide, and is collected in dilute hydrochloric acid. The liquid in the distilling-flask must be kept alkaline to prevent iridium chloride from distilling over with the ruthenium. The distillate is evaporated to dryness, and the residue ignited in hydrogen, cooled in carbon dioxide and weighed as metal. 

I ioileciicarbonyltetrairidium, Ir4(CO)i2, can be prepared in good yields by the method used for the first time by Hieber and Idigully1 from iridium chloride or from an alkali hexachloro-... 

Chloro- and other halo- containing carbonyl compounds of iridium may also be synthesized under mild conditions. Unlike [Rh(CO)2Cl]2, [Ir(CO)2Cl] is not obtainable by the direct reaction of an iridium chloride solution with CO. Instead, [Ir(CO)2Cl2]n (48) is obtained in low yields by reaction between IrCl3-H20 and carbon monoxide. The predominant mononuclear compound obtained upon carbonylation of iridium chloride salts is the tricarbonyl [Ir(CO)3Cl] (49), which appears in the sohd state to be a polymeric array consisting of stacking square-planar Ir(CO)3Cl units with short fr-Ir bonds. Even though [Ir(CO)3Cl] is polymeric, it is sublimable and is stiU a convenient source of iridium(I) containing carbon monoxide. (49) will react with a number of nucleophiles to form mononuclear iridium carbonyl complexes. 

Besides Rhodamine 6G (see above). Malachite Green and Crystal Violet form ion-associates with the anionic iridium chloride-SnCl j complexes and these ean also be used for flotation-spectrophotometric determination of iridium. The molar absorptivity e with Malachite Green is 1.55-10 [77,78]. 

On treating an iridium chloride with SnClj and NEt4Cl, (NEt4)2[Ir(SnCl3)5] was obtained K7lrSn7Cl4F2o and K7lr[SnC04C2)2]s were also characterized. ... 

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