- Synthesis of iridaboratranes bearing phosphine-tethered borane: Reversible CO/PR3 (R = Me, OMe, OEt) substitution reactions induced by a σ-electron-acceptor borane ligand
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The iridaboratrane [{o-(Ph2P)C6H4} 3B]IrH(CO) (1-Ir), bearing phosphine-tethered borane, was synthesized via phosphine ligand exchange between the tris(triphenylphosphine) carbonyl hydride IrH(CO)(PPh3)3 (2-Ir) and the tris(phosphine) borane {o-(Ph2P)C6H4}3B (3). 1-Ir was fully characterized on the basis of its 1H, 11B, and 31P NMR spectra, X-ray diffraction analysis, and elemental analysis. Density functional theory calculations revealed the important properties of the σ-acceptor borane ligand that led to its unique electron distribution in 1-Ir. The borane ligand extracts a significant amount of electron density from the iridium center, but the iridium center maintains an electron density similar to that of the boron-free compound 2-Ir by decreasing π back-donation from Ir to CO and strengthening the donation from the phosphorus atom (or by weakening the dmetal-σP-R interaction). The properties of the borane ligand can promote the reversible CO/PR3 (R = Me, OMe, OEt) substitution reaction.
- Kameo, Hajime,Hashimoto, Yasuhiro,Nakazawa, Hiroshi
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- Action of triphenylphosphine on [Rh(HCOO)(PPh3) 2(CO)]. A novel synthetic route to [HRh(PPh3) 3(CO)]
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Rhodium(I) carbonyl formato complex, trans-[Rh(HCOO)(PPh3) 2(CO)], on heating in propanol-2 in the presence of excess triphenylphosphine converts into carbonyl hydride complex, [HRh(PPh 3)3(CO)], with a good yield. The reaction provides a new and attractive method of synthesis of [HRh(PPh3)3(CO)].
- Varshavsky, Yuri S.,Cherkasova, Tatiana G.,Podkorytov, Ivan S.
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- Homogeneous and alumina supported rhodium complex catalyzed hydrogenation
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The complex Rh (OH) (CO) (PPh3)2 in homogeneous as well as in γ-Al2O3 supported system was used as catalyst precursor for hex-1-ene and benzene hydrogenation at 80 °C and 6.5 atm of H2. X-ray diffract
- Treciak, A. M.,Ziolkowski, J. J.,Jaworska-Galas, Z.,Mista, W.,Wrzyszcz, J.
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- The crystal and molecular structure of a new polymorph of carbonylhydridotris(triphenylphosphine)rhodium(I) having a Rh-H stretching absorption at 2013 cm-1
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A new polymorph of HRh(CO)(PPh3)3, with a υRh-H of 2013 cm-1, has been isolated by crystallization from tert-butyl methyl ether/tetrahydrofuran.The crystals are monoclinic (space group P21/n), with a=21.48(2) Angstroem, b=14.92(2) Angstroem, c=14.52(1) Angstroem, β=107.95(8) deg.A final R value of 0.065 was obtained using 2243 reflections which had Inet > 2.5?(Inet).The structure of the new polymorph has a similar coordination geometry to the known polymorph, but a different conformation of one of the phenyl rings.
- Babra, I. S.,Morley, L. S.,Nyburg, S. C.,Parkins, A. W.
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- Hydroformylation of dihydrofurans catalyzed by rhodium complex encapsulated hexagonal mesoporous silica
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HRh(CO)(PPh3)3 encapsulated hexagonal mesoporous silica (HMS) is found to be an efficient heterogeneous catalyst for the selective hydroformylation of 2,3-dihydrofuran (2,3DHF) and 2,5-dihydrofuran (2,5DHF). The Rh-complex encapsulated in situ in the organic phase of template inside the pores of HMS was found to act as nano phase reactors. Conversion of 2,3-DHF and 2,5-DHF and selectivity of the corresponding aldehydes were thoroughly investigated by studying the reaction parameters: catalyst amount, substrate concentration, partial as well as total pressure of CO and H2, and temperature. The selectivity for the formation of tetrahydrofuran-2-carbaldehyde (THF-2-carbaldehyde) from the hydroformylation of 2,3-DHF was found to be more than the selectivity of the formation of tetrahydrofuran-3-carbaldehyde (THF-3-carbaldehyde) from 2,5-DHF. The reaction paths are suggested and discussed for the selective formation of the corresponding aldehydes. The catalyst was elegantly separated and effectively recycled for six times.
- Khokhar, Munir D.,Shukla, Ram S.,Jasra, Raksh V.
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- Hydroformylation of Alkenes in a Planetary Ball Mill: From Additive-Controlled Reactivity to Supramolecular Control of Regioselectivity
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The Rh-catalyzed hydroformylation of aromatic-substituted alkenes is performed in a planetary ball mill under CO/H2 pressure. The dispersion of the substrate molecules and the Rh-catalyst into the grinding jar is ensured by saccharides: methyl-α-d-glucopyranoside, acyclic dextrins, or cyclodextrins (CDs, cyclic oligosaccharides). The reaction affords the exclusive formation of aldehydes whatever the saccharide. Acyclic saccharides disperse the components within the solid mixture leading to high conversions of alkenes. However, they showed typical selectivity for α-aldehyde products. If CDs are the dispersing additive, the steric hindrance exerted by the CDs on the primary coordination sphere of the metal modifies the selectivity so that the β-aldehydes were also formed in non-negligible proportions. Such through-space control via hydrophobic effects over reactivity and regioselectivity reveals the potential of such solventless process for catalysis in solid state.
- Cousin, Kévin,Menuel, Stéphane,Monflier, Eric,Hapiot, Frédéric
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supporting information
p. 10564 - 10568
(2017/08/22)
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- "On water" hydroformylation of 1-hexene using Rh/PAA (PAA = polyacrylic acid) as catalyst
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A new rhodium catalyst, Rh/PAA, obtained by the immobilization of Rh(acac)(CO)2 on polyacrylic acid (PAA), was successfully applied for the hydroformylation of 1-hexene in a water medium. Spectroscopic analysis evidenced that rhodium in Rh/PAA was chemically bonded to polyacrylic acid and formed a hydrido-carbonyl rhodium compound in reaction with H2/CO. Excellent results (98% conversion, TOF 1000) were obtained in the "on water" hydroformylation of 1-hexene when Rh/PAA was used together with a hydrophobic phosphine (triphenylphosphine, tri-p-tolylphosphine, or diphenyl(2-methoxyphenyl) phosphine). A similar efficiency was also obtained for a system composed of Rh(acac)(CO)2 and PPh3, tested in the same conditions in water. the Partner Organisations 2014.
- Alsalahi,Trzeciak
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p. 30384 - 30391
(2014/08/05)
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- Ethylene hydroformylation in imidazolium-based ionic liquids catalyzed by rhodium-phosphine complexes
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In this research, the catalytic activity of a rhodium-based (Rh) catalyst with imidazolium-based ionic liquids (IBILs) as solvents for ethylene hydroformylation was studied. The structures of IBILs had an important influence on the activity and stability of the Rh catalyst. The IBILs with longer cation side chains, which were the strong steric hindrances around the Rh catalyst, were more unfavorable for the catalytic activity. The turnover frequency (TOF) of the Rh catalyst was 10627 h-1 when [Bmim][BF4] was used as solvent. The activity of the Rh complexes in the ionic liquid is better than they do in toluene. We used electrospray ionization mass spectrometry to characterize the catalyst after the reaction and found that [Bmim]+ acts as a ligand of the Rh catalyst to form a new active catalytic site [Rh(CO)(PPh3)2(Bmim)(BF4)]+ through the coordination of the Rh atom with the imidazole-2-C group of [Bmim][BF 4], and it was essential for the stabilization of the Rh catalyst and prevented the formation of low-active Rh clusters. In addition, the catalyst recycling test showed that the Rh catalyst could be reused with [Bmim][BF 4] as solvent without obvious loss of catalytic activity.
- Diao, Yanyan,Li, Jing,Wang, Ling,Yang, Pu,Yan, Ruiyi,Jiang, Li,Zhang, Heng,Zhang, Suojiang
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- Rh(I) carbonyl carboxylato complexes: Spectral and structural characteristics. Some reactions of coordinated formate group
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Complexes [Rh(μ-RCOO)(CO2)]2, where R = H, CH 3, CF3 (I, II, III, respectively) are synthesized by reacting anhydrous carboxylic acids with Rh(Acac)(CO2) crystals. In compounds I, II, III, and trans-Rh(RCOO)(PPh3)2(CO), where R = H, CH3, CF3 (IV, V, VI, respectively), ν(CO) and 1J(CRh) increase and δ13C decreases with the increasing electronegativity of R (CH3 3). In the case complexes IV, V, and VI, the values of δ31P and 1J(PRh) decrease in the same order. Complexes I and V are studied by X-ray diffraction analysis. Intramolecular (2.946 A) and intermolecular (3.127 A) Rh-Rh distances in a columnar structure I are close, i.e., the structure contains infinite chains of metal atoms. Interaction of IV with chlorinated solvents results in trans-RhCl(PPh3)2(CO). When heated with an excess of PPh3 in propanol-2, compound IV transforms to HRh(PPh3)3(CO). The latter reaction was suggested as a basis of a new method that can be used to obtain HRh(PPh 3)3(CO).
- Varshavskii,Cherkasova,Podkorytov,Korlyukov,Khrustalev,Nikol'skii
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p. 121 - 131
(2008/10/09)
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- C-C and C-H bond activation of dialkylmethylenecyclopropane promoted by rhodium and iridium complexes. Preparation and structures of M(η1:η2-CH2CR2CH=CH 2)(CO)(PPh3)2 and trans-M(CH=CHCMeR 2)(CO)(PPh3)2 (M = Rh, Ir, R = CH 2CH2Ph)
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2,2-Bis(2-phenylethyl)-1-methylenecyclopropane reacts with RhH(CO)(PPh 3)3 at room temperature and with IrH(CO)(PPh 3)3 at 70°C to form the 3-butenyl complexes of these metals, M{η1:η2-CH2C(CH 2CH2Ph)2CH=CH2}(CO)(PPh 3)2 (1, M = Rh; 2, M = Ir). Heating 1 at 55°C liberates 1,1-bis(2-phenylethyl)-1,3-butadiene, while the thermal reaction of 2 at 110°C forms a mixture of 3-methyl-3-vinyl-1,5-diphenyl-1-pentene (48% NMR yield) and 3-methyl-3-vinyl-1,5-diphenylpentane (15% NMR yield). The reactions of excess amounts of 2,2-bis(2-phenylethyl)-1-methylenecyclopropane with RhH(CO)(PPh3)3 at 55°C and with IrH-(CO)(PPh 3)3 at 115°C afford the alkenyl complexes trans-Rh{(Z)-CH=CHC(CH2CH2Ph)2CH 3}-(CO)(PPh3)2 (3) and trans-Ir{(E)-CH= CHC(CH2CH2Ph)2CH3}(CO)(PPh 3)2 (4), respectively. The reaction mechanisms are discussed on the basis of the results of the reactions under different conditions. HC≡CC(CH2CH2Ph)2CH 3 reacts with MH(CO)(PPh3)3 (M = Rh, Ir) to afford the alkynyl complexes trans-M{C≡CC(CH2CH 2Ph)2CH3}(CO)(PPh3)2 (5, M = Rh; 6, M = Ir) via oxidative addition of the C(alkyne)-H bond to the metal center and subsequent elimination of H2.
- Itazaki, Masumi,Yoda, Chikako,Nishihara, Yasushi,Osakada, Kohtaro
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p. 5402 - 5409
(2008/10/09)
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- Rhodium complexes HRh[P(NC4H4)3]4 and HRh(CO)[P(NC4H4)3]3 as active catalysts of olefins and arenes hydrogenation : X-ray structure of HRh(CO)[P(NC4H4)3]3
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The rhodium hydrido complexes HRh[PPhx(NC4H4)3-x]4 (x=0-2) and HRh(CO)[PPhx(NC4H4)3-x]3 have been obtained in reactions of Rh(acac)(CO)2+PPhx(NC4H4) 3-x with H2 or H2/CO (0.1 MPa, room temperature) respectively. The crystal structure of HRh(CO)[P(NC4H4)3]3 has been determined. The complex is slightly distorted trigonal bipyramidal with H and CO ligands occupying the axial positions. The Rh atom is located 0.336 A out of plane of the three equatorial P atoms. The Rh-H distance in two crystallographically independent molecules is 1.51(5) and 1.69(6) A respectively. The complexes HRh[P(NC4H4)3]4 and HRh(CO)[P(NC4H4)3]3 are active catalysts of hydrogenation reaction of olefins and arenes (cyclohexene, 1,3-cyclohexadiene, 1,4-cyclohexadiene, propenylbenzene, styrene, toluene) at 353 K and 0.5 MPa H2. The TOF up to 836 mol/mol Rh per h have been obtained.
- Trzeciak, Anna M.,Glowiak, Tadeusz,Ziolkowski, Jozef J.
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p. 159 - 164
(2007/10/03)
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- Rhodium hydride (HRh(CO)(PPh3)3) and rhodium carbonyl (Rh4(CO)8L4) complexes obtained by reaction of Rh(acac)(CO)(L) type complexes with methanol and formaldehyde
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Rhodium(I) complexes of Rh(acac)(CO)(L) type (where L = P(OMe)3, P(OEt)3, P(OPh)3, P(O-o-MeC6H4)3, PPh3, P(p-MeC6H4)3, PMePh2, AsPh3) react with alcohols and formaldehyde.In absence of free ligand (L) only carbonyl complexes of formula Rh4(CO)8(L)4 (or Rh
- Trzeciak, A. M.,Ziolkowski, J. J.
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p. 239 - 244
(2007/10/02)
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- Protonation of cobalt, rhodium, and iridium hydrides with fluorocarbon acids. Synthesis, reactivity, and dynamic properties of (Ph3P)3Rh+ and its derivatives
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Protonation of a variety of Co, Rh, and Ir hydrides with the fluorocarbon acids H2C(SO2CF3)2, PhCH(SO2CF3)2, HN(SO2CF3)2, H2C(SO2C8F17)2, and C8F17SO3H is reported. The Co and Ir hydrides form cationic dihydrides. Protonation of (Ph3P)4RhH affords [(Ph3P)3Rh][HC(SO2CF3)2]. The stereochemical nonrigidity of [(Ph3P)3Rh]+ in solution has been characterized by 31P DNMR. Reactions of this 14-electron Rh(I) compound are described, including the solid-state carbonylation to yield [(Ph3P)3Rh(CO)2] [HC(SO2CF3)2]. Carbon monoxide in the dicarbonyl salt is labile, and it dissociates in solution to give [(Ph3P)3Rh(CO)] [HC(SO2CF3)2]. Fluorocarbon acids having long-chain perfluoroalkyl groups are useful in synthesizing salts that have high solubility in aromatic hydrocarbons.
- Siedle,Newmark,Howells
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p. 2473 - 2478
(2008/10/08)
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- Reaction of carbon monoxide with hydridobis[di(tertiary phosphine)]rhodium(I) complexes. Synthesis and structure of the metal-metal bonded carbonyl-bridged dimers [Rh(CO)(diphosphine)]2(μ-CO)2
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Reaction of the hydridorhodium(I) complexes RhH(P-P)2 with carbon monoxide leads to formation of the dimeric carbonyl-bridged complexes [Rh(CO)(P-P)]2(μ-CO)2 with concomitant elimination of hydrogen, where P-P represents the di(tertiary phosphines): 1,2-bis(diphenylphosphino)ethane, 1,3-bis(diphenylphosphino)propane, and 2,3-O-isopropylidene-2,3-dihydroxy-1,4-bis(diphenylphosphino)butane, abbreviated as dppe, dppp, and diop, respectively. The Rh2(dppp)2(CO)4·1/ 2C6H6 complex exists as two crystallographically independent binuclear molecules possessing approximate C2 symmetry (triclinic, space group P1, a = 17.222 (3) A?, b = 21.513 (4) A?, c = 15.479 (3) A?; α = 90.929 (11)°, β = 108.358 (9)°, γ = 86.303 (12)°; Z = 4; R = 0.047 and Rw = 0.056 for 8068 reflections with I ≥ 3σ(I)). The structure is described in terms of two square pyramids (with phosphorus apical) sharing an edge formed by the two bridging carbonyl ligands, the mean angle between basal planes being 82.6°; a formal metal-metal single bond is indicated. Important bond lengths are Rh-Rh = 2.725 (1) and 2.709 (1) A?, Rh-P(basal) = 2.340 (3)-2.399 (3) A?, Rh-P(apical) = 2.316 (3)-2.340 (3) A?, Rh-CO(bridging) = 2.036 (9)-2.067 (10) A?, and Rh-CO(terminal) = 1.920 (11)-1.944 (11) A?. Low-temperature 31P{H} NMR spectra are consistent with the rigid structure; at room temperature the pairs of phosphorus atoms become chemically equivalent, probably via carbonyl site exchange since the 13C NMR spectrum is a single, broad resonance. Spectroscopic data for all three complexes indicate the same structure in each case. Like the corresponding bis(triphenylphosphine) species, the complexes are active catalysts for hydrogenation, isomerization, and hydroformylation of terminal olefins.
- James, Brian R.,Mahajan, Devinder,Rettig, Steven J.,Williams, Gregory M.
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p. 1452 - 1458
(2008/10/08)
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- ELECTROCHEMISTRY OF COORDINATION COMPOUNDS. XX. ELECTROGENERATED Rh(CO)(PPh3)3 AND Ir(CO)(PPh3)3
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The redox behaviour of the d8 complexes + (M=Rh, Ir) was studied on platinum electrode in 1,2-dimethoxyethane by cyclic voltammetry, differential pulse voltammetry, and potentiostatic coulometry.The complexes show two reversible one-electron reductions consistent with the formation of the rare zerovalent M(CO)(PPh3)3 and the anionic - derivatives, respectively.The reduced species were characterized by ESR and IR spectroscopy.A significant feature is that the one-electron reduced intermediates, in spite of their radical nature, react very easily with molecules capable of reacting as proton rather than H-atom sources to give the hydride species HM(CO)(PPh3)3.A tentative interpretation of this behaviour is suggested.
- Zotti, Gianni,Zecchin, Sandro,Pilloni, Giuseppe
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- Rhodium Nitrosyl Complexes
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The reactions of nitrosyl chloride and nitrosyl bromide with rhodium(I) complexes containing triphenylphosphine and triphenylarsine have been studied.These reactions result in the formation of the complexes of the type (X = Cl, Br; L = PPh3, AsPh3) and Rh(NO)X3L2.Reactions of Rh(CO)(NO)ClX(PPh3)2 (X = Cl, Br) with hydrazine hydrate afford PhH(CO)(PPh3)3 and a highly hygroscopic red complex X (X = Cl or Br).The probable structures of these complexes have been proposed on the basis of elemental analyses, spectroscopic (IR, UV and EPR) and magnetic data.
- Pandey, K. K.,Agarwala, U. C.
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p. 673 - 676
(2007/10/02)
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