Hydrations iridium

Rhodium(III) hydroxide is an ill-defined compound Rh(0H)3.nH20 (n 3) obtained as a yellow precipitate by careful addition of alkali to Na3RhCl6-Addition of imidazole solution to suitable aqua ions leads to the precipitation of active rhodium(III) hydroxides formulated as Rh(0H)3(H20)3, Rh2(/x-0H)2(0H)4(H20)4 and Rh3(/z-0H)4(0H)5(H20)5 [31]. Hydrated iridium(III) hydroxide is obtained as a yellow precipitate from Ir3+ (aq.) at pH 8. 

Although the redox reaction mechanisms of iridium oxide are still not clear, most researchers believe that the proton exchange associated with oxidation states of metal oxides is one of the possible pH sensing mechanisms [41, 87, 100, 105], During electrochemical reactions, oxidation state changes in the hydrated iridium oxide layer are... 

Examples for electrochromic behavior upon electrochemical oxidation can be found among group VIII metal oxides. Thin films of transparent hydrated iridium oxide turn blue-black, whereas nickel oxide switches from pale green to brown-black, possibly due to the absorbance of Ni3+ centers [26]. The systems are much less thoroughly investigated and a detailed mechanistic explanation is not known. However, proton extraction and anion insertion have been suggested. 

Hydrated Iridium Sesquioxide, Ir203.5H20, is obtained as an olive-green precipitate on addition of the requisite quantity of potassium hydroxide solution to one of chloriridite. If excess of potash is taken no precipitate appears, since the sesquioxide dissolves as rapidly as formed, yielding an olive-green solution, from which, however, it is pre< itated on addition of acid. 

Hydrated Iridium Dioxide, Ir02.2H20, results (1) when excess of caustic alkali is added to a solution of chloriridate or of iridium tetrachloride. Any sesquioxide simultaneously produced passes into solution, but is converted into the dioxide by boiling in air, by addition of hydrogen peroxide, or by passing a current of oxgen through the solution. 

Beck and coworkers211 have reviewed transition metal complexes of the fulminate ion, CNO, which bonds to the metal via the carbon atom. Fulminate complexes are, in general, similar to those with CN ligands. An extensive series of stable, non-explosive fulminates has been examined, including [Ir(CNO)6](AsPh4)3. [Ir(CNO)6]3- was prepared from hydrated iridium(III) chloride and Hg(CNO)2, and characterized by IR spectroscopy.21"1... 

A 150-ml., three-necked, round-bottomed flask is charged with 2.0 g. of hydrated iridium trichloride, 22 ml. of 2-propanol (isopropyl... 

Organometallic compounds such as [Cp Ir(0H2)3]S04 can be precursors for electrodeposition of a heterogeneous hydrated iridium oxide material that is an excellent electrocatalyst for water oxidation to O2. The deposit is not formed from standard Ir salts and may consist of small (Ir02) clusters n = 2,3) held together by carboxylate ligands formed in the oxidative degradation of Cp. ... 

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. 

The photochemistry and photophysics of [Ir(terpy)2], prepared for the first time, and of [Ir(phen)3], allegedly prepared pure for the first time, have been described. Quantum yields, in acetonitrile solution, are reported, and the efiTects of added mercury(II) chloride described. The preparation of [Ir(SSS)Cl3], where SSS = 1,4,7-trithiacyclononane, (71), from hydrated iridium trichloride and ligand normally takes many hours, but this synthesis can be achieved in seconds, and with very high yield, in a microwave... 

Dye-sensitized photoelectrochemical cell is used to split water under visible light. For example, an O2 evolution catalyst is formed by hydrated iridium oxide (Ir02 H20) nanoparticles attached to Ru-complex sensitizer molecules. An excited electron from LUMO is injected into the conduction band of Ti02. The outer circuit transfers this electron to a counter electrode (Pt). The water is then reduced to form hydrogen gas [41]. After water oxidation to O2, the dye returns to the ground state on accepting an electron from the I1O2 H20 nanoparticle. 

---