62792-06-7Relevant articles and documents
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.
SOME RHODIUM(I) AND RHODIUM(III) COMPLEXES WITH THE TRIPOD-LIKE LIGANDS RC(CH2PPh2)3 (R=Me: triphos; R=Et: triphos-I) AND THE X-RAY CRYSTAL STRUCTURE OF
Ott, J.,Venanzi, L. M.,Ghilardi, C. A.,Midollini, S.,Orlandini, A.
, p. 89 - 100 (2007/10/02)
The syntheses of (8, triphos=CH3C(CH2PPh2)3) and the related compound (triphos-I=EtC(CH2PPh2)3) are described, and the X-ray crystal structure of the latter is reported.The crystals are monoclinic space group P21/a, a 15.985(6), b 19.683(7), c 11.900(4) Angstroem, β 103,73(6) degree, Z=4.The structure was solved by the heavy atom method and refined by full-matrix leastsquares to the conventional R factor value of 0.057 for 2649 observed reflections.The metal atom is octahedrally coordinated by three phophorus atoms and by three hydrogen atoms, each trans to one phosphorus.Complex 8 has been shown to react with CO to give (2).Compound 2 reacts with CH2=CHCO2Me to give only the branched insertion product .The complex has been re-investigated and was obtained in a single isomeric form which has been assigned a five-coordinate structure.The five-coordinate compounds (X=Br and I) are also described.