- Oxygenation Studies. Part 7. Catalytic Dioxygenation of Cyclo-octa-1,5-diene at a Rhodium Centre
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Studies on the oxygenation of cyclo-octa-1,5-diene by molecular oxygen using as catalysts (1), and related dioxygen complexes in the presence of excess PPh3 are reported.A regioselective homoco-oxygenation of the diene is found to occur with (1) to give cyclo-octane-1,4-dione, in competition with some homoco-oxygenation of PPh3. 18O-Labelling experiments establish that both oxygens in a molecule of (1) are transferred to a molecule of the diene and initial rate measurements indicate that the slow step in the catalytic cycle follows displacement of one phosphine ligand in (1) by the diene.An overall mechanistic cycle, involving a sequence of five-, seven-, and four-membered metallacyclic intermediates, is suggested.
- Read, Gordon,Urgelles, Miguel
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- Synthesis of a square-planar rhodium alkylidene N-heterocyclic carbene complex and its reactivity toward alkenes
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The first rhodium alkylidene square-planar complex stabilized by an N-heterocyclic carbene ligand, RhCl(=CHPh)(IPr)PPh3 (2; IPr = 1,3-bis(2,6-diisopropylphenyl)imidazol-2-carbene), has been prepared by reaction of RhCl(IPr)(PPh3)2 (1) with phenyldiazomethane and its dynamic behavior in solution studied. Treatment of 2 with alkenes results in the formation of the η2-olefin complexes RhCl(η2- CH2=CHR)(IPr)PPh3 (3, R = H; 4, R = Ph; 5, R = OEt) and new olefins arising from the coupling of the alkylidene with the alkenes, likely via a metallacyclobutane intermediate.
- Palacios, Laura,Miao, Xiaowei,Di Giuseppe, Andrea,Pascal, Simon,Cunchillos, Carmen,Castarlenas, Ricardo,Perez-Torrente, Jesus J.,Lahoz, Fernando J.,Dixneuf, Pierre H.,Oro, Luis A.
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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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- Hydrogenation of acrylonitrile-butadiene rubber latex using in situ synthesized RhCl(PPh3)3 catalyst
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Catalytic hydrogenation of acrylonitrile-butadiene rubber (NBR) latex was achieved by using in situ synthesized RhCl(PPh3)3 catalyst. Water-soluble rhodium salt (RhCl3) was used as the catalyst precursor which was reacted in situ with triphenylphosphine (PPh3) to form RhCl(PPh3)3. Compared with using solid RhCl(PPh3)3, hydrogenation of NBR latex using the in situ RhCl(PPh3)3 showed a faster hydrogenation reaction. Based on the retention of catalyst in the polymer, it was revealed that the efficiency of in situ synthesis and the diffusion of the catalyst from the aqueous phase into the polymer particles were crucial in achieving the required high degree of hydrogenation. As a result, it was discovered that by introducing a small amount of alcohol (e.g. RhCl3 = 0.52 mmol/L, PPh3 = 18 mmol/L, ethanol/total NBR latex = 1/10 volume ratio) to the feed latex, the in situ synthesized catalyst could be used in the hydrogenation reaction very efficiently.
- Liu, Yin,Wei, Zhenli,Pan, Qinmin,Rempel, Garry L.
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- Synthesis of Ammonium Ions and Nitrosylation Reactions using Nitrosyl Chloride and Alkyl Nitrites
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Nitrosyl chloride (NOCl) reacts with RuCl3*xH2O in the presence of PPh3 in different alcohols leading to the formation of ammonium ions and under mild experimental conditions, through reductive deoxygenation.Some parameters affecting th
- Khan, M. Ishaque,Agarwala, U. C.
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- A ternary Rh complex catalyst highly active and stable in the hydrogenation of acrylonitrile-butadiene rubber
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An Rh-based complex, T-Rh-PPh3, was developed through a facile one-step process. The T-Rh-PPh3 exhibited high activity and air stability in the hydrogenation of acrylonitrile-butadiene rubber. The enhanced air stability can be ascribed to the phenolic hydroxyl structures in tannin.
- Cao, Peng,Wu, Meng,Zou, Rui,Zhang, Liqun,Yue, Dongmei
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- Synthesis of Silicon and Germanium-Containing Heterosumanenes via Rhodium-Catalyzed Cyclodehydrogenation of Silicon/Germanium-Hydrogen and Carbon-Hydrogen Bonds
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A three-step synthesis of C3-symmetric trisilasumanene and trigermasumanene, heteroanalogues of the π-bowl sumanene, was achieved using a threefold rhodium-catalyzed cyclodehydrogenation of Si/Ge-H and C-H bonds as the key step. Trigermasumanene was proven to adopt a planar geometry by single crystal X-ray diffraction for the first time. The optical properties were also investigated by UV-vis and fluorescence spectroscopy.
- Zhou, Dandan,Gao, Ya,Liu, Bingxin,Tan, Qitao,Xu, Bin
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- The Structure of Crystalline trans-Dichlorobis(triphenylphosphine)rhodium(II), a Square Planar Rhodium(II) Monomer: Isolation of the Proposed Paramagnetic Impurity in Wilkinson's Catalyst
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trans-Dichlorobis(triphenylphosphine)rhodium(II), a square planar rhodium(II) monomer, has been isolated and characterized spectroscopically and crystallographically.
- Ogle, Craig A.,Masterman, T. Craig,Hubbard, John L.
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- Dimeric rhodium-ethylene NHC complexes as reactive intermediates for the preparation of tetra-heteroleptic NHC complexes
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Dimeric rhodium complexes with various N-heterocyclic carbene (NHC) ligands have been synthesized and fully characterized. X-ray analysis unambiguously confirms the bimetallic nature of these complexes, and in all cases one molecule of ethylene is coordinated to each metal center in an η2- fashion. The Rh atoms are also coordinated to one NHC ligand and are interconnected by two μ-chlorine bridges. The dimeric nature of the complexes is most likely stabilized due to the significant steric bulk around the metal centers provided by the carbene ligands. Consistent with this, modulating the steric properties and backbone saturation of the ligands was shown to have a significant effect on the stability and geometry of the complexes. Treatment of the carbene dimers with ligands such as PPh3 results in cleavage of the dimers and a unique synthesis of tetra-heteroleptic complexes of the general formula [ClRh(NHC)(PR3)(CH2=CH2)]. The stabilities of these compounds have been assessed, and although decomposition to Wilkinson's complex is observed upon treatment with an excess of phosphine for prolonged times, the presence of the ethylene ligand provides greatly increased stability compared with the bis-phosphine analogues [ClRh(NHC)(PPh 3)2].
- Zenkina, Olena V.,Keske, Eric C.,Wang, Ruiyao,Crudden, Cathleen M.
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- Rhodium-catalyzed reductive carbonylation of aryl iodides to arylaldehydes with syngas
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The reductive carbonylation of aryl iodides to aryl aldehydes possesses broad application prospects. We present an efficient and facile Rh-based catalytic system composed of the commercially available Rh salt RhCl3·3H2O, PPh3 as phosphine ligand, and Et3N as the base, for the synthesis of arylaldehydes via the reductive carbonylation of aryl iodides with CO and H2 under relatively mild conditions with a broad substrate range affording the products in good to excellent yields. Systematic investigations were carried out to study the experimental parameters. We explored the optimal ratio of Rh salt and PPh3 ligand, substrate scope, carbonyl source and hydrogen source, and the reaction mechanism. Particularly, a scaled-up experiment indicated that the catalytic method could find valuable applications in industrial productions. The low gas pressure, cheap ligand and low metal dosage could significantly improve the practicability in both chemical researches and industrial applications.
- Chen, Suqing,Liu, Zhenghui,Mu, Tiancheng,Wang, Peng,Yan, Zhenzhong,Yu, Dongkun,Zhao, Xinhui
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p. 645 - 656
(2020/05/14)
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- Mechanochemical dehydrocoupling of dimethylamine borane and hydrogenation reactions using Wilkinson's catalyst
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Mechanochemistry enabled the selective synthesis of the recherché orange polymorph of Wilkinson's catalyst [RhCl(PPh3)3]. The mechanochemically prepared Rh-complex catalysed the solvent-free dehydrogenation of Me2NH·BH3 in a ball mill. The in situ-generated hydrogen (H2) could be utilised for Rh-catalysed hydrogenation reactions by ball milling.
- Schumacher, Christian,Crawford, Deborah E.,Ragu?, Branimir,Glaum, Robert,James, Stuart L.,Bolm, Carsten,Hernández, José G.
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supporting information
p. 8355 - 8358
(2018/08/04)
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- Synthesis method of rhodium(triphenylphosphine)carbonylacetylacetonate
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The invention discloses a synthesis method of rhodium(triphenylphosphine)carbonylacetylacetonate.The method includes the steps of conducting backflow reaction on rhodium chloride trihydrate and a triphenylphosphine solution to prepare triphenylphosphine rhodium chloride, mixing prepared triphenylphosphine rhodium chloride with N,N-dimethylformamide under the protection of nitrogen, then adding acetylacetone, conducting backflow heating reaction, cooling to the room temperature, concentrating a solution, adding icy water, standing, separating out crystals, conducting filtering, washing filter cakes with water, and conducting vacuum drying to obtain rhodium(triphenylphosphine)carbonylacetylacetonate.By means of the new synthesis method, intermediates are replaced with triphenylphosphine rhodium chloride capable of being stably stored in air, the step-by-step yield and once through yield of the product are increased, and benzene and alkane type toxic solvent are not used; by means of environment-friendly type solvent ethyl alcohol, production cost is reduced, and remarkable economic and environment advantages are achieved.
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Paragraph 0017
(2016/12/01)
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- The continuous reaction device and method of using the continuous composite (by machine translation)
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PROBLEM TO BE SOLVED: compounds with high productivity can be generated. SOLUTION: 1 the raw material supply section 12 and a first, a second and 2 the raw material supply section 14, and a reaction part 18, the first reaction part 1 from the raw material supply section 1 and a second quantity of raw material, the raw material supply section 2 from the first reaction part 2 and a second quantity of raw material, the raw material supply section 1 from the first reaction part 1 and a second temperature of the raw material, the raw material supply section 2 from the first reaction part 2 and supplied to the temperature of the raw material, and having a control part 22, a continuous reaction device as shown in the drawing. Selected drawing: fig. 1 (by machine translation)
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Paragraph 0186
(2017/01/02)
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- Convenient synthesis and molecular structure of the cyclometallated complex [IrCl(H)(C6H4PPh2)(PPh3)2]
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Dedicated to Professor Hubert Schmidbaur on the occasion of his 80th birthday The reaction of [{Ir(μ-Cl)(coe)2}2] (coe=cis-cyclooctene) with triphenylphosphane (molar ratio of Ir to P=1 : 3) in dichloromethane at room temperature afforded after a short reaction time the cyclometallated complex [IrCl(H)(C6H4PPh2)(PPh3)2] (1) in almost quantitative yield. The molecular structure of the title compound 1 was determined by an X-ray diffraction study.
- B?ttcher, Hans-Christian,Mayer, Peter
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p. 1237 - 1240
(2015/06/16)
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- Fluxionality of [(Ph3P)3M(X)] (M = Rh, Ir). the red and orange forms of [(Ph3P)3Ir(Cl)]. Which phosphine dissociates faster from wilkinson's catalyst?
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NMR studies of intramolecular exchange in [(Ph3P) 3Rh(X)] (X = CF3, CH3, H, Ph, Cl) have produced full sets of activation parameters for X = CH3 (Ea = 16.4 ± 0.6 kcal mol-1, ΔH? = 16.0 ± 0.6 kcal mol-1, and ΔS? = 12.7 ± 2.5 eu), H (Ea = 10.7 ± 0.2 kcal mol-1, ΔH ? = 10.3 ± 0.2 kcal mol-1, and ΔS ? = -7.2 ± 0.8 eu), and Cl (Ea = 16.3 ± 0.2 kcal mol-1, ΔH? = 15.7 ± 0.2 kcal mol-1, and ΔS? = -0.8 ± 0.8 eu). Computational studies have shown that for strong trans influence ligands (X = H, Me, Ph, CF3), the rearrangement occurs via a near-trigonal transition state that is made more accessible by bulkier ligands and strongly donating X. The exceedingly fast exchange in novel [(Ph3P) 3Rh(CF3)] (12.1 s-1 at -100 °C) is due to strong electron donation from the CF3 ligand to Rh, as demonstrated by computed charge distributions. For weaker donors X, this transition state is insufficiently stabilized, and hence intramolecular exchange in [(Ph 3P)3Rh(Cl)] proceeds via a different, spin-crossover mechanism involving triplet, distorted-tetrahedral [(Ph3P) 3Rh(Cl)] as an intermediate. Simultaneous intermolecular exchange of [(Ph3P)3Rh(Cl)] with free PPh3 (THF) via a dissociative mechanism occurs exclusively from the sites cis to Cl (E a = 19.0 ± 0.3 kcal mol-1, ΔH ? = 18.5 ± 0.3 kcal mol-1, and ΔS ? = 4.4 ± 0.9 eu). Similar exchange processes are much slower for [(Ph3P)3Ir(Cl)] which has been found to exist in orange and red crystallographic forms isostructural with those of [(Ph 3P)3Rh(Cl)].
- Goodman, Jenni,Grushin, Vladimir V.,Larichev, Roman B.,MacGregor, Stuart A.,Marshall, William J.,Roe, D. Christopher
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p. 12013 - 12026
(2010/10/19)
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- Rates and mechanism of rhodium-catalyzed [2+2+2] cycloaddition of bisalkynes and a monoalkyne
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The mechanism of RhCl(PPh3)3-catalyzed [2+2+2] cycloaddition of alkynes is investigated in the case of the reaction of symmetrical diynes la and lb with the monoalkyne 3 (HOCH2- Cdeg;2OH), leading to highly subs
- Dachs, Anna,Torrent, Anna,Pla-Quintana, Anna,Roglans, Anna,Jutand, Anny
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p. 6036 - 6043
(2010/03/04)
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- Phosphinorhodium-catalyzed dehalogenation of chlorinated and fluorinated ethylenes: Distinct mechanisms with triethylsilane and dihydrogen
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Catalytic dehalogenation of chlorinated and fluorinated ethylenes by (PR3)3RhCl complexes is described. The C-Cl and C-F bonds are activated by the catalyst in the presence of triethylsilane (Et 3SiH) or dihydrogen (H
- Peterson, Alicia A.,Thoreson, Kristen A.,McNeill, Kristopher
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p. 5982 - 5991
(2010/02/16)
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- The F/Ph rearrangement reaction of [(Ph3P)3RhF], the fluoride congener of Wilkinson's catalyst
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The fluoride congener of Wilkinson's catalyst, [(Ph3P) 3RhF] (1), has been synthesized and fully characterized. Unlike Wilkinson's catalyst, 1 easily activates the inert C-Cl bond of ArCl (Ar = Ph, ρ-tolyl) under mild conditions (3 h at 80 °C) to produce trans-[(Ph 3P)2Rh(Ph2PF)(Cl)] (2) and ArPh as a result of C-Cl, Rh-F, and P-C bond cleavage and C-C, Rh-Cl, and P-F bond formation. In benzene (2-3 h at 80 °C), 1 decomposes to a 1:1 mixture of trans-[(Ph 3P)2Rh(Ph2PF)(F)] (3) and the cyclometalated complex [(Ph3P)2Rh(Ph2PC6H 4)] (4). Both the chloroarene activation and the thermal decomposition reactions have been shown to occur via the facile and reversible F/Ph rearrangement reaction of 1 to cis-[(Ph3P)2Rh(Ph) (Ph2PF)] (5), which has been isolated and fully characterized. Kinetic studies of the F/Ph rearrangement, an intramolecular process not influenced by extra phosphine, have led to the determination of Ea = 22.7 ± 1.2 kcal mol-1, ΔH? 22.0 ± 1.2 kcal mol-1, and ΔS? = -10.0 ± 3.7 eu. Theoretical studies of F/Ph exchange with the [(PH3)2(PH 2Ph)RhF] model system pointed to two possible mechanisms: (i) Ph transfer to Rh followed by F transfer to P (formally oxidative addition followed by reductive elimination, pathway 1) and (ii) F transfer to produce a metallophosphorane with subsequent Ph transfer to Rh (pathway 2). Although pathway 1 cannot be ruled out completely, the metallophosphorane mechanism finds more support from both our own and previously reported observations. Possible involvement of metallophosphorane intermediates in various P-F, P-O, and P-C bond-forming reactions at a metal center is discussed.
- Macgregor, Stuart A.,Roe, D. Christopher,Marshall, William J.,Bloch, Karen M.,Bakhmutov, Vladimir I.,Grushin, Vladimir V.
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p. 15304 - 15321
(2007/10/03)
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- METHOD FOR PRODUCING CHLOROTRIS(TRIPHENYLPHOSPHINE) RHODIUM (I)
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The invention relates to a method for producing chlorotris(triphenylphosphine) rhodium (I) by reacting an RhCl3 solution with triphenylphosphine in mixtures of C2-C5 alcohols and water and subsequently cooling and filtering the resultant crystalline precipitate. Said method is characterised in that the mixture of reactants is heated to a temperature of approximately 75 °C and is then maintained at a temperature of between 80 and 110 °C. The method leads to increases in terms of the yield and the quality of the resultant crystals.
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Page/Page column 5-6
(2008/06/13)
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- Dehalogenation of hexachlorocyclohexanes and simultaneous chlorination of triethylsilane catalyzed by rhodium and ruthenium complexes
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Complexes RhCl(PPh3)3 and RhH2Cl(P iPr3)2 catalyze the dehalogenation of γ-hexachloro-cyclohexane to benzene and the simultaneous chlorination of HSiEt3 to ClSiEt3. In
- Esteruelas, Miguel A.,Herrero, Juana,Olivan, Montserrat
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p. 3891 - 3897
(2008/10/09)
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- A high-yield conversion of trans-Rh(Cl)(CO)(PPh3)2 to Rh(Cl)(PPh3)3
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The first high-yield procedure for conversion of trans-Rh(Cl)(CO)(PPh3)2 to Rh(Cl)(PPh3)3 has been achieved by utilization of the commercially available17 DPPA as a carbonyl ligand abstraction reagent.
- O'Connor, Joseph M.,Ma, Junning
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p. 1866 - 1867
(2008/10/08)
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- Reactions of catecholborane with wilkinson's catalyst: Implications for transition metal-catalyzed hydroborations of alkenes
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Reactions of catecholborane (HBO2C6H4) with RhCl(PPh3)3 (1) yield a variety of products depending on the B/Rh ratio, solvent, and temperature. Of particular relevance to catalyzed alkene hydroboration is degradation of HBO2C6H4 to B2(O2C6H4)3/'BH 3' and the dihydride RhH2Cl(PPh3)3 (3). The molecular structure of 3, determined by X-ray diffraction, has meridional phosphine ligands and cis hydrides. Catalyst systems formed from in situ addition of PPh3 to [Rh(μ-Cl)(COD)]2 (COD = 1,5-cyclooctadiene) are fundamentally different from Wilkinson's catalyst; RhCl(COD)(PPh3) forms initially, but the reaction of this with PPh3 is slow. Monitoring catalyzed hydroborations using Wilkinson's catalyst and catecholborane by multinuclear NMR spectroscopy, prior to oxidative workup, showed that alkylboranes were formed with some sterically hindered alkenes. With 2-methylbut-2-ene (24), for example, we observed significant quantities of disiamylborane, (CHMeCHMe2)2, formed via addition of 'BH3' to 24. When excess PPh3 was added to the catalyst system, however, the desired alkylboronate ester was formed in high yield. Partial oxidation of RhCl(PPh3)3 had a significant effect on product (and D-label) distributions. Detailed investigations of catalyzed additions of DBO2C6H4 to allylic silyl ethers CH2=C(Me)CRR′(OSitBuMe2) (R, R′ = H, Me) demonstrated that deuterium incorporation at the carbon bonded to boron in the primary alcohol product occurs only with freshly prepared Wilkinson's catalyst or when excess PPh3 is added to the oxidized catalyst. With freshly prepared Wilkinson's catalyst, addition of H2 (or D2) to these substrates is a significant competing reaction and appreciable catalytic formation of vinylboronate esters is also observed. The latter presumably arise via insertion of alkene into a Rh-B bond, followed by β-hydride elimination. Subsequent in situ addition of H2 (DH or D2) to these vinylboronate esters provides an alternative explanation to α-deuterium incorporation into the resulting primary alcohols.
- Burgess, Kevin,Van Der Donk, Wilfred A.,Westcott, Stephen A.,Marder, Todd B.,Baker, R. Thomas,Calabrese, Joseph C.
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p. 9350 - 9359
(2007/10/02)
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- Para-hydrogen-induced polarization in rhodium complex-catalyzed hydrogenation reactions
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The homogeneous hydrogenation of PhCCH catalyzed by RhClL3, Rh(COD)L2+, and Rh(COD)dppe+ (L=PPh3; COD=1,5-cyclooctadiene; dppe=1,2-bis(diphenylphosphino)ethane) has been investigated using para-hydrogen-induced polarization (PHIP) which shows that in accord with earlier studies, for RhClL3 the addition of H2 is reversible, whereas for Rh(COD)(dppe)+ and Rh(COD)L2+, H2 addition in hydrogenation catalysis is irreversible.
- Kirss, Rein U.,Eisenberg, Richard
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p. C22 - C26
(2007/10/02)
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- Reaction Dynamics of the Tricoordinate Intermediates MCl(PPh3)2 (M = Rh, or Ir) as Probed by the Flash Photolysis of the Carbonyls MCl(CO)(PPh3)2
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Reported is a kinetics flash photolysis investigation of the rhodium(I) complex RhCl(CO)(PPh3)2 in benzene solution.These results are interpreted in terms of the transient formation of the unsaturated species RhCl(PPh3)2 (A), an intermediate crucial to proposed mechanisms of Wilkinson's catalyst reactions such as olefin hydrogenation, but which has not been the subject of previous direct investigation.Kinetics of the dimerization of A and of the reactions of this transient with CO, C2H4, PPh3, and H2 are also described.The second-order rate constant for the reaction with H2 is 1.0E5/M.s in good agreement with the value >7E4/M.s estimatted by Halpern and Wong (J.Chem.Soc., Chem.Commun. 1973, 629) from kinetics investigations of the hydrogenation of RhCl(PPh3)3.Furthermore, the equilibrium constant for triphenylphosphine dissociation from RhCl(PPh3)3 can be calculated as 2.3E-7 M from the ratio of the first-order dissociation rate constant 0.68/s determined by those workers and the second-order rate constant 3.0E6/M.s for the back reaction determined here.Rates of the subsequent reactions of other adducts formed from A and various ligands with the CO liberated in the flash experiment were also determined.Flash photolysis studies of the iridium(I) analogue IrCl(CO)(PPh3)2 in benzene demonstrated CO photolabilization in this case as well.The back reaction of the resulting transient species IrCl(PPh3)2 with CO displayed second-order kinetics with the respective rate constant 2.7E8/M.s.These results are discussed in terms of the catalytic mechanisms involving such species.
- Wink, David A.,Ford, Peter C.
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p. 436 - 442
(2007/10/02)
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- Synthesis, structure, and ligand-promoted reductive elimination in an acylrhodium ethyl complex
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8-Quinolinecarboxaldehyde and [(C2H4)2RhCl]2 reacted to give a polymeric acylrhodium ethyl compound which was solubilized by pyridine to give chloroethyl(8-quinolinecarbonyl-C,N)(pyridine)rhodium. This compound was stable in the presence of amine ligands, but phosphine ligands caused rapid reductive elimination. Intermediates in the reductive elimination were observed at -40°C by using 1H, 13C, and 31P NMR in the case of the ligand PPh3. In the first-formed intermediate PPh3 displaced pyridine. The resulting five-coordinated Rh(III) complex reductively eliminated (with an observed first-order rate constant of 3.7 × 10-4 s-1 at -40°C) to give an η2-ketone Rh(I) intermediate. With excess phosphine RhCl(PPh3)3 and 8-quinolinyl ethyl ketone were the final products. Recrystallization of the starting pyridine complex from pyridine-ether gave Cl(C2H5)Rh(C10H6NO)(C 5H5N)2·1/2C 4H10O (chloroethyl(8-quinolinecarbonyl-C,N)bis(pyridine)rhodium-hemi(diethyl ether)), whose structure was determined by single-crystal X-ray diffraction. The compound crystallizes in the triclinic space group P1 with two molecules in the unit cell a = 8.933 (3) A?, b = 17.573 (8) A?, c = 7.760 (2) A?, α = 97.57 (3)°, β = 98.04 (2)°, and γ = 79.98 (3)°. The least-squares refinement with anisotropic thermal parameters for all non-hydrogen atoms converged at RF = 0.046 (RwF = 0.055) for 2595 observed reflections and 262 parameters refined.
- Suggs, J. William,Wovkulich, Michael J.,Cox, Sherman D.
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p. 1101 - 1107
(2008/10/08)
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- Metallacarboranes in Catalysis. 3. Synthesis and Reactivity of exo-nido-Phosphinerhodacarboranes
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The carbon-substituted closo-bis(triphenylphosphine)hydridorhodacarborane , the carbon-substituted exo-nido-bis(triphenylphosphine)rhodacarborane complexes , and the salt (1+)(1-) were prepared by the reaction of the carborane anions (1-) (Ia-e) with in benzene.Complexes IIa,c exhibited a closo-exo-nido equilibrium in solution.The exo-nido complexes can be regarded as being composed of an (1+) cation bound to a (1-) anion cage via two exo polyhedral three-center, two-electron interactions (Rh-H-B bridges) with terminal hydrogen atoms.The (1+) moiety can apparently rotate with respect to and, in some cases, migrate about the polyhedral surface of the cage.Complex IIA reacted with 2 equiv of PCy3 ( Cy = cyclohexyl) to generate the mixed phosphine exo-nido complex (IIIa).Reaction of the exo-nido-bis(triphenylphosphine)rhodacarboranes with good ? donors or CO displaced the rhodium from the carborane cage to give cationic species of the form (1+), (1+), (1+) (L = PPh3, S = solvent); (1+) (L = PEt3); (1+) (L-L = dppe); and (1+) (L-L-L = Ph2PCH2CH2P(Ph)CH2CH2PPh2 = triphos, L' = PPh3).The (1+) complexes (Va-e) reacted further to generate closo species of the general formula .The 3,1,2-isomer was obtained when R = R' = Me (VIIc), R, R' = μ-(CH2)3- (VIId), and R, R' = μ-(1',2'-CH2C6H4CH2-) (VIIa); but in the cases of R = Ph, R' = Me and R = 1'-(closo-1',2'-C2B10H11), R' = H, a polytopal rearrangement occurred, resulting in the formation of , R = Me, R' = Ph (VIb) and R = H, R' = 1'-(closo-1',2'-C2B10H11) (VIe).The complexes IIa-d and IIIa underwent oxidative addition of H2 to give dihydrido Rh(III) products in which the (1+) or (1+) fragment remains bonded to the carborane cage through two three-center, two-electron Rh-H-B interactions.Molecular structures of two representative exo-nido-rhodacarboranes (IIb and IIIa) along with that of closo-rhodacarborane (IIa) have been determined and are formally presented in the following paper of this series.
- Long, Judith A.,Marder, Todd B.,Behnken, Paul E.,Hawthorne, M. Frederick
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p. 2979 - 2989
(2007/10/02)
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- Hyponitrite Complexes of Rhodium(III)
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The hyponitrite complexes of rhodium(III), 2N2O2> (X = Cl, Br), 2N2O2> have been prepared by the reactions of NOX (X = Cl, Br) or NOBr3 with Rh(CS)Cl(PPh3)2.These hyponitrite complexes react with HCl in the presence of triphenylphosphine to give halo-complexes RhX(PPh3)3 (X = Cl, Br).The products are characterized by elemental analyses, and various physicochemical methods.
- Pandey, K. K.,Jain, K. C.,Agarwala, U. C.
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