Oxidative addition of different electrophiles with rhodium(I) carbonyl complexes of unsymmetrical phosphine–phosphine monoselenide ligands

Direct Observation of Kinetically Competent Surface Intermediates upon Ethylene Hydroformylation over Rh/Al2O3 under Reaction Conditions by Time-Resolved Fourier Transform Infrared Spectroscopy

“…These spectral assignments and explanation of the kinetic behavior are borne out by observation of bands in the CH stretching region, isotopic labeling studies, and comparison with infrared spectra of related species reported in the literature. Specifically, the carbonyl stretch mode at 1675 cm À1 agrees with noble metal complexes containing propionyl ligands, which have carbonyl stretching modes in the range 1640À1701 cm À1 according to literature reports: RhCl 2 (COC 2 H 5 )(PMe 2 Ph) 3 [ν(CdO) 1640 cm À1 ], 33,34 36 Further, the band at 2869 cm À1 is assigned to the CH stretching mode of the ethyl group of the propionyl intermediate (Rh-CO-C 2 H 5 ) as its growth behavior is consistent with that of the 1675 cm À1 band. Similarly, the growth behavior of a ν(CH) product band at 2715 cm À1 with its distinct induction period, shown in Figure 11, agrees with that of the 1737 cm À1 absorption of propionaldehyde (Figure 10A).…”

Synthesis and characterization of new RhI complexes bearing CO, PPh3 and chelating P,O- or Se,Se-ligands: Application to hydroformylation of styrene

“…Also, the complex cis-[RhI-(CO){Ph 2 PCH 2 P(S)Ph 2 -P,S}] [8] exhibited better catalytic activity for this reaction compared to the classic Monsanto catalyst [RhI 2 (CO) 2 ] À , under mild conditions. Likewise, in a series of papers, Dutta et al have explored the efficiency of Rh I catalyst precursors modified with P,O- [9] and P,Se- [10,11] diphosphine ligands, including kinetic studies with respect to oxidative addition reactions on these complexes. In addition, Rh I complexes with bidentate P,O-ligands, were shown to catalyze the hydrogenation and the isomerization of 1-hexene, as well as the transfer dehydrogenation of cyclooctane [12].…”

“…One can observe the shift to lower energy of the m(PO) band going from 1 to 2 due to deprotonation and chelation of the bidentate ligand, the generation of the dicarbonyl complex in solution upon reaction with CO and, finally, the existence of a single m(CO) band in 3 after the reaction series is complete. Such Rh I complexes have been shown to exhibit high catalytic activity towards hydroformylation of olefins [26], or similar catalytic reactions like carbonylation of methanol [11,25].…”

Ethene Hydroformylation Catalyzed by Rhodium Dispersed with Zinc or Cobalt in Silanol Nests of Dealuminated Zeolite Beta

“…As the reaction proceeded, there was a gradual increase in the intensity of the bands at 3000–2800 and 1500–1350 cm –1 (Figure A), and new features appeared in the range of 1750–1500 cm –1 , which are assigned to CO stretching vibrations of adsorbed acyl species, presumably propionyl (CH 3 CH 2 CO*). − It has been reported that acyl groups in various Rh complexes exhibit CO stretching vibrations at 1705–1635 cm –1 . − Support for these assignments can be drawn from the observation of acyl species exhibiting bands at 1695, 1673, and 1645 cm –1 during ethene hydroformylation catalyzed by RhH­(CO)­L 3 (L = P­(3,5-(CF 3 ) 2 (C 6 H 3 ) 3 ) in supercritical CO 2 …”