165751-18-8Relevant academic research and scientific papers
Comparison of a range of rhodium-based catalysts for the hydroformylation of selected alkenes
Dickson,Gladiali,Bowen,Campi,Jackson,Jonasson,McGrath,Paslow,Polas,Renton
, p. 133 - 146 (1999)
To determine whether the activity and selectivity of bimetallic catalysts improve during the hydroformylation of alkenes compared to their monometallic counterparts, the hydroformylation of styrene, 1-hexene, and a variety of amino- and phosphino-alkenes using four Rh-based catalyst systems ((OC)4W(μ-PPh2)2RhH(CO)(PPh3), (OC)2RhMo(CO)3(C5H4PPh2), (OC)2RhW(CO)3(C5H4PPh2), and [Rh(OAc)2]2/PPh3) was investigated. The Rh-catalyzed reactions of unsaturated amines with H2/CO differed in chemo- and regioselectivity depending on the catalyst and the reaction conditions. The reactions of unsaturated amides differed in product ratios with varying catalyst systems.
Transition-metal derivatives of the functionalized cyclopentadienyl ligand. XVI. Synthesis of the bridged complexes [(μ-η5-C5H4PPh2)M(CO) 2]2 (M = Cr, Mo, W). X-Ray crystal structure of the dihydride derivative [μ-η5-C5H4PPh2W(CO) 2H]2
Brumas-Soula, Brigitte,Dahan, Francoise,Poilblanc, Rene
, p. 15 - 23 (2008/10/08)
Four synthetical methods, implying basically the oxidation of the anionic species [(η5-C5H4PPh2)M(CO) 3]- [M = Cr, (2a-), Mo (2b-), W (2c-)] to produce the new homobimetallic derivatives [(μ,η5-C5H4PPh2)M(CO) 2]2 (M-M), [M = Cr (1a), Mo (1b), W (1c)] of the heterodifunctional diphenylphosphinocyclopentadienyl bridging ligand, have been investigated. The first approach proceeds in two steps: thus the electrochemical oxidation of the complexes 2a- and 2b- leads to the metal-metal bonded dimetallic complexes [(η5-C5H4PPh2)M(CO) 3]2 (M-M), [M = Cr (5a), Mo (5b)]; the irradiation of these complexes 5a and 5b with a high-pressure Hg lamp affords the corresponding decarbonylated bridged complexes 1a and 1b. The second method, using silver tetrafluoroborate as the oxidant of the anions 2a- to 2c-, leads to the formation of tetrametallic cyclic complexes of silver and Group 6 transition metals [(μ-η5-C5H4PPh2[M(CO) 3Ag]2, [M = Cr (6a), Mo (6b), W (6c)] but the splitting of these compounds into bimetallic complexes 1a-c and metallic silver appears neither easy nor selective. As a third procedure, the hydrido complexes (η5-C5H4PPh2)M(CO)3H [M = Cr (3a), Mo (3b), W (3c)] are irradiated with a high-pressure Hg lamp. This procedure is useful to prepare 1b but is non-selective in the two other cases, affording mainly bimetallic dihydrido-bridged complexes [(μ-η5-C5H4PPh2)M(CO) 2H]2 [M = Mo (7b), W (7c)] and 1a or 1b, as a result of the expected competition between the dehydrogenation and the decarbonylation processes. The X-ray molecular structure of 7c points out the transoid disposition of the hydrido ligands, which could well be a factor of its inertness in a spontaneous dehydrogenation process towards 1c. Finally, the most efficient method requires the preliminary preparation of the iodo complexes (η5-C5H4PPh2)M(CO)3I [M = Cr (4a), Mo (4b), W (4c)], which are reacted in toluene with their anionic parents 2-. This last method is particularly useful for preparing 1a and 1c.
