124223-20-7Relevant articles and documents
Kinetics and mechanisms of homogeneous catalytic reactions. Part 9. Hydroformylation of 1-hexene catalyzed by a rhodium system containing a tridentated phosphine
Rosales, Merlin,Chacón, Gustavo,González, Angel,Pacheco, Inés,Baricelli, Pablo J.,Melean, Luis G.
, p. 110 - 114 (2009/01/23)
A kinetic study of the homogeneous hydroformylation of 1-hexene to the corresponding aldehydes (heptanal and 2-methyl-hexanal) was carried out by using a rhodium catalyst formed by the addition of 1 equiv. of 1,1,1-tris(diphenylphosphinomethyl)ethane (triphos) to the complex Rh(acac)(CO)2 under mild reaction conditions (80 °C, 2-10 atm of syn-gas) in toluene; linear to branched ratios (l/b) varied from 1.3 to 5.8, depending on the reaction conditions. The reaction rate is first order with respect to the concentration of Rh, fractional order with respect to 1-hexene concentration and zero order with respect to dissolved hydrogen concentration. Increasing the CO pressure up to a threshold value of 2.1 atm accelerates the reaction, further increments inhibit the reaction. Complex RhH(CO)(κ3-triphos) was isolated and characterized by IR and NMR (1H and 31P{H}). The kinetic data and related co-ordination chemistry are consistent with a mechanism involving RhH(CO)(κ2-triphos) as the active species and the migratory insertion of the alkene into the metal-hydride bond as the rate limiting step. This catalytic cycle is rather similar to that proposed for RhH(CO)(PPh3)3 and for RhH(CO)2(dppe); however, the presence of a triphos ligand co-ordinated in a κ2 mode through the cycle resulted in l/b ratio higher than those obtained in systems containing bidentated phosphines.
Mimicking the HDS activity of promoted tungsten catalysts. A homogeneous modeling study using a two-component tungsten/rhodium system
Bianchini, Claudio,Jiménez, M. Victoria,Meli, Andrea,Moneti, Simonetta,Patinec, Véronique,Vizza, Francesco
, p. 5696 - 5705 (2008/10/08)
Reaction of W(CO)5THF with (triphos)Rh[η3-S(C6H4)CH=CH2] (1), obtained by insertion of the 16e- fragment [(triphos)RhH] into the C2-S bond of benzo[b]thiophene (BT), gives the dimer (triphos)Rh[η3-(CO)5WS(C6H 4)CH=CH2] (2; triphos = MeC(CH2PPh2)3). Unlike 1, the heterometal dimer 2 reacts with H2 (30 atm) above 70°C in THF, undergoing the desulfurization of the C-S-inserted BT. As a result, a mixture of the hydrido carbonyl species (triphos)RhH(CO), ethylbenzene, and WSx (xav = 1.5) is obtained. High-pressure NMR spectroscopy in the temperature range from 20 to 70°C shows that the desulfurization step is preceded by the formation by the dimer (triphos)RhH(μ-H)[μ-o-S(C6H4)C2H 5]W(CO)4 (5), in which the Rh and W centers are held together by bridging 2-ethylthiophenolate and hydride ligands. Complex 5 has been characterized in both the solid state (single-crystal X-ray analysis) and solution (multinuclear NMR spectroscopy). The desulfurization of 5 occurs also by thermolysis in THF at 120°C under a nitrogen atmosphere. Reaction of 5 with CO (30 atm, 40°C) gives the complex [(triphos)Rh(CO)2][(CO)5W(o-S(C6H 4)C2H5)] (8), in which the thiolate ligand is η1-S bound to the tungsten atom in the complex anion [(CO)5W-(o-S(C6H4)C2H 5)]-. The hydrogenation of 8 (30 atm of H2, > 70°C) gives exclusively free 2-ethylthiophenol. The carbonylation of 2 (30 atm of CO, room temperature) results in the formation of [(triphos)Rh(CO)2][(CO)5W(o-S(C6H 4)CH=CH2)] (3), in which the 2-vinylthiophenolate ligand is η1-S bound to the tungsten atom. The possible similarity in the C-S bond cleavage mechanism in the desulfurization of 5 to those occurring in the HDS over promoted heterogeneous catalysts is discussed.
Reversible arm-off dissociation of the tripodal MeC(CH2PPh2)3 in HRh(CO)[MeC(CH2PPh2)3] under hydroformylation conditions
Kiss, Gábor,Horváth, István T.
, p. 3798 - 3799 (2008/10/08)
The reversible arm-off dissociation of the tripodal ligand MeC(CH2PPh2)3 in HRh(CO) [η3-MeC-(CH2PPh2)3] (1) under H2/CO (1:1) was studied by high-pressure IR and NMR s
