Metals and Catalyst Precursors

The rhodium catalyst has to mediate hydroformylation as well as hydrogenation. Since both reactions require different conditions in tandem reactions, a compromise has to be found. 

H2 to afford B. In the cases where the HAM is initiated with the latter, it has to be converted first into A. This may affect, for example, the rate of the HAM in ionic liquids (ILs) or the conversion of long-chain olefins [37,38]. By using both precatalysts together, regioselectivity as well as the chemoselectivity could be improved. 

Bearing in mind that iridium complexes are particularly active for the hydrogenation of imines, dual catalysts consisting of rhodium and iridium complexes [RhCl(COD)]2/[IrCl(COD)]2 have been suggested [39, 40]. Also the combined use of Rh(acac)(CO)2/Ru3(CO)j2 in AfAf-dimethylformamide (DMF) proved to be advantageous [41]. If the water gas shift reaction or its reversed version is utilized as sources for CO or H2, ruthenium catalysts give superior results [42-44]. HAM can be speeded up by irradiation with microwaves [45]. 

In the HAM of internal olefins with rhodium Xantphos-type ligands, the same steric dependency on the bite angle concerning the formation of the linear amine as in hydroformylation was observed. An increase in the bite angle up to 125°, which was realized with Nixantphenoxaphos (1), resulted in an increase in n-regioselectivity, whereas with wider angles a reversed tendency was 

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