Iridium hydrogenation

Okada, M., Ogura, S., Dino, W.A., Wilde, M., Flikutani, K. and Kasai, T. (2005) Reactivity of gold thin films grown on iridium Hydrogen dissociation. Applied Catalysis A General, 291, 55-61. 

Since there are unresolved issues in the fine detail of reaction mechanism, it is worth recalling an earlier publication on reactive intermediates in iridium hydrogenation [61]. In general, conventional Ir diphosphine complexes turnover slowly or not at all when enantioselective hydrogenation of standard substrates is attempted, and essentially all the practical and useful recent synthetic contri-... 

Arylation, olefins, 187, 190 Arylketimines, iridium hydrogenation, 83 Arylpropanoic acid, Grignard coupling, 190 Aspartame, 8, 27 Asymmetric catalysis characteristics, 11 chiral metal complexes, 122 covalently bound intermediates, 323 electrochemistry, 342 hydrogen-bonded associates, 328 industrial applications, 8, 357 optically active compounds, 2 phase-transfer reactions, 333 photochemistry, 341 polymerization, 174, 332 purely organic compounds, 323 see also specific complexes Asymmetric induction, 71, 155 Attractive interaction, 196, 216 Autoinduction, 330 Axial chirality, 18 Aza-Diels-Alder reaction, 220 Azetidinone, 44, 80 Aziridination, olefins, 207... 

There are a number of possible mechanisms for oxidative addition and the precise one followed depends on the nature of the reacting partners. Vaska s complex [lr(PPh3)2C0CI] has been extensively studied and it reacts differently with hydrogen and methyl iodide. Hydrogen is added in a c/s fashion, consistent with concerted formation of the two new iridium-hydrogen bonds. The... 

Reactions of Salts of Iridium,.—Hydrogen sulphide in excess causes the precipitation of dark brown iridium sesquisulphide, Ir2S3. If the iridium is present in solution in the tetravalent condition, as for example in the form of alkali chlor-iridates, M2IrCl8 or 2MQ.IrCld, the dark solution is first decolorised and a yellowish white precipitate of sulphur forms in consequence of the reduction of the iridium salt to the trivalent condition, namely, as IrCl3. When this has been accomplished the brown sesquisulphide is obtained. 

In the reaction of IrH(CO)(PPh3)3 with tetracyanoethylene (tcne) one molecule of tcne inserts into the iridium-hydrogen bond and a second molecule of tcne co-ordinates 7T-wise to the metal to give the product... 

Crabtree s catalyst shows some tendency to form inactive trimeric heptahy-dride species under low alkene concentration, and the stability and durability of monophosphine monoamine iridium hydrogenation catalysts have been recently reported (62). 

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