124223-20-7Relevant academic research and scientific papers
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.
Efficient rhodium catalysts for the hydrogenolysis of thiophenic molecules in homogeneous phase
Bianchini, Claudio,Casares, Juan A.,Meli, Andrea,Sernau, Volker,Vizza, Francesco,Sanchez-Delgado, Roberto A.
, p. 3099 - 3114 (2008/10/09)
In the presence of strong bases, the C - S insertion complexes (triphos)Rh[η3-S(C6H4)CH=CH2] and (triphos)Rh(η3-SCH=CHCH=CH2) as well as the π-alkyne complex [(triphos)Rh(η2-MeO
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
Tripodal polyphosphine ligands in homogeneous catalysis. 1. Hydrogenation and hydroformylation of alkynes and alkenes assisted by organorhodium complexes with MeC(CH2PPh2)3
Bianchini,Meli,Peruzzini,Vizza,Frediani,Ramirez
, p. 226 - 240 (2008/10/08)
This paper describes the synthesis and the chemical-physical properties of a number of new mononuclear organorhodium complexes of triphos. A detailed study on the hydrogenation reactions of various alkenes and alkynes and on the hydroformylation reactions of alkenes has been carried out. Also, the study compares and contrasts the catalytic activity of complexes containing participative ligands with that of (i) related mononuclear species containing non-participative ligands, and (ii) related dirhodium complexes.
η3-MeC(CH2PPh2)3/rhodium complexes utilize phosphine arm dissociation mechanisms at 25°C
Thaler, Eric G.,Folting, Kirsten,Caulton, Kenneth G.
, p. 2664 - 2672 (2007/10/02)
Reaction of RhMe3(triphos) (triphos = MeC(CH2PPh2)3) with CO generates acetone and RhMe(CO)(triphos), which reacts with further CO to give Rh[C(O)Me](CO)(triphos). The structure of RhMe(CO)(triphos) shows one strained P-Rh-P bond angle between equatorial ligands (90.80 (5)°) in a trigonal bipyramid, together with intramolecular steric effects that cause a small equatorial CO-Rh-axial(CH3) C/C angle of 79.09 (25)°. The acetyl and methyl complexes react with H2 at 25°C to produce acetaldehyde and methane, respectively, together with RhH(CO)(triphos). Reaction of CO with RhH3(triphos) is even faster than with RhMe3(triphos) to give H2 and RhH(CO)(triphos), together with a CO hydrogenation product. These results show that these clean stoichiometric conversions, as well as a variety of isotopic exchange reactions of the Rh(I) and Rh(III) compounds with D2 and 13CO, occur by preequilibrium dissociation of one arm of the triphos ligand at 25°C. One such species, Rh[C(O)Me](CO)2(η2-triphos), is directly detectable and reveals the mechanism of exchange of Rh[C(O)Me](13CO)(triphos) with 12CO. The coordination of CO to Rh(H)3(η2-triphos) is proposed to generate a dihydrogen complex, thus accounting for the CO-induced elimination of H2. As suggested by these individual reactions, RhH(CO)(triphos) is a catalyst for olefin hydroformylation. The high n:iso selectivity mimics that of RhH(CO)(PPh3)3 in the presence of a large amount of added PPh3, a beneficial consequence of the chelate effect.
Nucleophilic attack on carbon monoxide in carbonyl phosphine complexes of rhodium(I) and ruthenium(II): A novel route to complexes of rhodium(-I)
Johnston, Gregory G.,Hommeltoft, Sven I.,Baird, Michael C.
, p. 1904 - 1909 (2008/10/08)
Reaction of [Rh(CO)2(triphos)]PF6 (triphos = MeC(CH2PPh2)3) with sodium borohydride in CD2Cl2 results in the formation of the hydride RhH(CO)(triphos) and the formyl complex Rh(HCO)(CO)(triphos). In contrast, treatment of [Rh(CO)2(triphos)]PF6 with excess methyllithium in THF results in the formation of the rhodium(-I) complex Li[Rh(CO)(triphos)]. The mechanism of this unusual reaction appears to involve (i) nucleophilic attack of MeLi on a carbonyl carbon of [Rh(CO)2(triphos)]PF6 to yield the acetyl complex Rh(MeCO)(CO)(triphos), (ii) attack by a second mole of MeLi on the acetyl group to produce the complex Li[Rh(Me2CO)(triphos)], and (iii) elimination of acetone to form product. In the presence of excess MeLi, the acetone reacts further to form tert-butoxide, which is also detected in the reaction mixture. The rhodium(-I) complex Li[Rh(CO)(triphos)] reacts with proton sources to yield the hydride RhH(CO)(triphos), with alkyl and acyl halides to form the alkyl complexes RhR(CO)(triphos) (R = Me, Et, Ph, MeCO), with trimethyltin chloride to form Rh(SnMe3)(CO)(triphos), and with CO to form Li[Rh(CO)2(η2-triphos)], with a pendant phosphine. The complex [Ru(CO)3(triphos)][AlCl4]2 can be synthesized by treating [RuCl-(CO)2(triphos)]Cl with AlCl3 under an atmosphere of CO. The dicationic complex [Ru(CO)3(triphos)]2+ is very susceptible to nucleophilic attack at CO and reacts with ethanol, water, and NaBH3CN to form the alkoxycarbonyl complex [Ru(CO2Et)(CO)2(triphos)]+, the hydride complex [RuH(CO)2(triphos)]+ (presumably via [Ru(CO2H)(CO)2(triphos)]+), and the formyl complex [Ru(HCO)(CO)2(triphos)]+, respectively.
Organorhodium(I) and -rhodium(III) complexes containing the ligand 1,1,1-tris((diphenylphosphino)methyl)ethane (triphos)
Johnston, Gregory G.,Baird, Michael C.
, p. 1894 - 1903 (2008/10/08)
Treatment of the complex [Rh(CO)2(triphos)]PF6 (triphos = MeC(CH2PPh2)3) with the ligands L (L = PMe3, PMe2Ph, PEt3, P(n-Bu)3, P(OMe)3, t-BuNC) resulted in the formation of complexes of the type [Rh(CO)L(triphos)]PF6. The analogous complexes of PPh3, ethylene, and propylene could not be prepared in this way but were synthesized by displacing molecular hydrogen from the complex [RhH2(CO)(trip-hos)]PF6, prepared by the photochemical oxidative addition of H2 to [Rh(CO)2(triphos)]PF6. The σ-bonded organorhodium(I) complexes RhR(CO)(triphos) (R = Me, Ph) were prepared by treating RhCl(CO)(triphos) with the appropriate alkyllithium reagent, and these compounds in turn were found to react readily with CO to form the acyl complexes Rh(RCO)(CO)(triphos). Addition of anhydrous HCl to the complex RhCl(CO)(triphos) resulted in the formation of a mixture of RhHCl2(CO)(triphos) and RhCl3(triphos), while addition of excess chlorine, bromine, or iodine to [Rh(CO)2(triphos)]PF6 resulted in the formation of the rhodium(III) complexes [RhX2(triphos)]PF6 (X = Cl, Br, I). These reacted in turn with methyllithium to form RhMe3(triphos), and with a variety of neutral ligands L to form the series [RhX2L(triphos)]PF6.
Rhodium Complexes with the Tripodal Triphosphine MeC(CH2PPh2)3 as Highly Reactive Systems for Hydrogenation and Hydroformylation of Alkenes
Bianchini, Claudio,Meli, Andrea,Peruzzini, Maurizio,Vizza, Francesco,Fujiwara, Yuzo,et al.
, p. 299 - 301 (2007/10/02)
The (triphos)Rh fragment is able to form strong bonds with several reactive species (hydride, alkyl, carbon monoxide, alkenes), some reactions of which are highly specific; preliminary results on the hydrogenation and hydroformylation of hex-1-ene using (triphos)RhH(C2H4) as catalyst precursor are discussed.
