Iridium and rhodium “PNP” aminodiphosphine complexes used as catalysts in the oxidation of styrene

Abstract

New Ir and Rh “PNP” aminodiphosphine complexes are effective catalysts in styrene oxidation with tert-butyl hydroperoxide as the oxidant. The Ir catalysts were more active than the Rh catalysts with high yields to benzaldehyde in comparison to styrene oxide.

The effects of metals and ligands on the oxidation of n-octane using iridium and rhodium “PNP” aminodiphosphine complexes

“…Our recent study on the application of these catalysts showed that these two families of complexes follow similar chemistry for styrene oxidation. 74 Therefore, 1a was only chosen for the initial optimization studies. The reaction was initially carried out at 80 °C with tert -butyl hydroperoxide (TBHP) as the oxidant in acetonitrile using catalyst 1a (Figure 2).…”

“…This clearly confirms the contribution of the nitrogen atoms of the ligands in these complexes in tuning the selectivity to certain products, besides the already discussed role in improving the catalyst basicity that was discussed in a previous study using these catalysts. 74 The deep oxidation process (ketone formation) is much slower with the rhodium catalysts in comparison to the Ir catalysts ( Figure 6), which is noted by the higher selectivity for the octanols (11%-41%), with catalyst 2b being the most selective (41%) and 2c being the least selective toward these octanols. As also noted with the iridium catalysts, the C(1) position is the least active, with the C(2) and C(3) positions being the most active carbons ( Table 1).…”

“…The complexes 1 and 2 ( Figure 1) were synthesized by the procedure reported elsewhere. 74 The PNP ligands were added to methanol/acetone mixtures (2:1; v/v), to which the metal complex precursor and NH 4 PF 6 salt were added. The complexes were characterized by NMR and infrared (IR) spectroscopy.…”

“…General reaction scheme and the structures of the complexes used as catalysts for the oxidation of n-octane. 74 Temperature optimization. Before optimizing the temperature for this reaction, another popular solvent [dichloroethane (DCE)] was tested for this reaction at the same temperature as for the optimized conditions in MeCN.…”

“…General reaction scheme and the structures of the complexes used as catalysts for the oxidation of n -octane. 74 …”