Studies on the bonding of polynuclear heteroaromatic nitrogen ligands to (pentamethylcyclopentadienyl)rhodium dication: the role of nitrogen versus .pi.-complexation on the regioselective hydrogenation of the nitrogen ring

Fish, Richard H.; Kim, Hoon Sik; Babin, James E.; Adams, Richard D.

doi:10.1021/om00100a035

Cited by 47 publications

(21 citation statements)

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“…Similar Table 1 Hydrogenation of Q (0.1 M) with the rhodium and iridium systems M 2 (COE) 4 tendencies were observed and explained by Fish et al [3][4][5], by Chin et al [7] and by some of us [8], and therefore no additional comments will be made. In order to gain further understanding of the mechanisms of the regioselective hydrogenation of heteroaromatic nitrogen substrates, the reaction of the dimeric iridium complex with each component of the catalytic mixture was carried out, with the aim of isolating or detecting some intermediates of the reaction; iridium dimer was chosen because of the higher stability of the species of this metal.…”

Section: Resultssupporting

confidence: 65%

“…The order of individual initial rate was A > Q > 5,6-BQ > 7,8-BQ > iQ, which suggests both steric and electronic effects. 4 containing dppe and triphos ligands.…”

Section: Resultsmentioning

confidence: 99%

“…The coordination chemistry experiments were carried out by the reaction of [Ir 2 (COE) 4 Cl 2 ] (110 mg, 0.12 mmol) with one equivalent of dppe or triphos and the corresponding nitrogen compound (0.5 mL) in benzene solution (15 mL), at room temperature, in the presence and in the absent of hydrogen.…”

Section: Methodsmentioning

confidence: 99%

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Regioselective Reduction of Quinolines Catalyzed by Rhodium and Iridium Complexes with mono-, di-, and tri-dentated Phosphine Ligands

et al. 2006

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The systems prepared in situ by addition of the corresponding equivalents of the respective phosphine (mono-, di-and tridentated), called M 2 Cl 2 (COE) 4 /n phosphine (M = Rh, Ir; and COE = cyclooctene), are efficient and regioselective precatalysts for the hydrogenation of quinoline, isoquinoline, 5,6-and 7,8-benzoquinoline and acridine. The Rh systems were more active than the corresponding Ir ones, being the systems with 1,1,1-tris(diphenylphosphinomethyl)ethane (triphos) more active than those with 1,2-bis(diphenylphosphino)ethane (dppe), except for the case of acridine, where the inversed tendencies were observed (Ir > Rh and dppe > triphos). The systems with triphenylphosphine showed the lowest activities.

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Section: Resultssupporting

confidence: 65%

“…The order of individual initial rate was A > Q > 5,6-BQ > 7,8-BQ > iQ, which suggests both steric and electronic effects. 4 containing dppe and triphos ligands.…”

Section: Resultsmentioning

confidence: 99%

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Regioselective Reduction of Quinolines Catalyzed by Rhodium and Iridium Complexes with mono-, di-, and tri-dentated Phosphine Ligands

et al. 2006

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“…Some homogeneous complexes have been found to catalyze the homogeneous reduction of Q, such as RuHCl(PPh 3 ) 3 [4], RhCl(PPh 3 ) 3 [5], [Rh(g 5 -Cp*)(NCMe) 3 ] 2? [6], [M(COD) (PPh 3 ) 2 ] ?…”

Section: Introductionmentioning

confidence: 99%

Kinetics and Mechanisms of Homogeneous Catalytic Reactions. Part 10. Regioselective Hydrogenation of Quinoline Catalyzed by the Systems M2Cl2(COE)4/2 Triphos [M = Rh, Ir; COE = Cyclooctene; Triphos = 1,1,1-Tris(diphenylphosphinomethyl)Ethane]

et al. 2009

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The systems prepared in situ by addition of two equivalents of 1,1,1-tris(diphenylphosphinomethyl)ethane (triphos) to M 2 Cl 2 (COE) 4 (M = Rh, Ir; COE = cyclooctene) showed to be efficient and regioselective precatalysts for the hydrogenation of quinoline. For both systems, kinetic studies lead to the rate laws rit was proposed that the catalytically active species are the cationic unsaturated complexes [M(Q)(triphos)] ? . The general mechanism involves a rapid and partial hydrogenation of these species to generate complexes of the type [M(H) 2 (Q)(triphos)] ? (isolated and characterized for M = Ir), which transfer the hydride ligands to the coordinated Q to yield species containing a 1,2-dihydroquinoline (DHQ) ligand, followed by a second oxidative addition of H 2 , considered as the rate-determining step of the cycle; hydrogen transfer toward the DHQ ligand yield THQ, regenerates the active species and restarts the catalytic cycle.

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“…The hydrogenation of quinoline (Q) to 1,2,3,4-tetrahydroquinoline (THQ) is an area of considerable interest because it is the first step of the hydrodenitrogenation (HDN) process [1][2][3]; some homogeneous complexes catalyze this reaction, such as RuHCl(PPh 3 ) 3 [4], RhCl(PPh 3 ) 3 [5], [Rh(g 5 -Cp*)(NCMe) 3 ] 2? [6], [M(COD)(PPh 3 ) x (NCPh) y ] ?…”

Section: Introductionmentioning

confidence: 99%

Kinetics and Mechanisms of Homogeneous Catalytic Reactions. Part 11. Regioselective Hydrogenation of Quinoline Catalyzed by Rhodium Systems Containing 1,2-Bis(diphenylphosphino)ethane

et al. 2011

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The system prepared in situ by addition of two equivalents of 1,2-bis(diphenylphosphino)ethane (dppe) to Rh 2 Cl 2 (COE) 4 (COE = cyclooctene) showed to be an efficient and regioselective precatalyst for the hydrogenation of quinoline (Q). This reaction showed to be independent of the Q concentration and of fractional order on H 2 and catalyst concentrations (1.5 and 0.6, respectively). The fractional order on catalyst concentration indicates that several catalytic species with different activities are present in the reaction medium; however, the cationic species [Rh (dppe) 2 ] ? was the only phosphorous-containing compound detected by 31 P{ 1 H} NMR. For the acac salt of this cationic bis(dppe) complex, a kinetic study led to the rate law r = {K 1 k 2 /(1 ? K 1 [H 2 ])}[M][H 2 ] 2 ; [M(Q)(j 2 -dppe) (j 1 -dppe)] ? was proposed as the catalytically active species (CAS) of the cycle. The general mechanism involves a reversible oxidative addition of H 2 to generate a dihydrido complex, which transfers the hydride ligands to the coordinated Q to yield species containing a 1,2-dihydroquinoline (DHQ) ligand, followed by a second oxidative addition of H 2 , considered as the rate-determining step of the cycle; hydrogen transfer toward the DHQ ligand yields THQ, regenerates the CAS and restarts the catalytic cycle.

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Studies on the bonding of polynuclear heteroaromatic nitrogen ligands to (pentamethylcyclopentadienyl)rhodium dication: the role of nitrogen versus .pi.-complexation on the regioselective hydrogenation of the nitrogen ring

Cited by 47 publications

References 0 publications

Regioselective Reduction of Quinolines Catalyzed by Rhodium and Iridium Complexes with mono-, di-, and tri-dentated Phosphine Ligands

Regioselective Reduction of Quinolines Catalyzed by Rhodium and Iridium Complexes with mono-, di-, and tri-dentated Phosphine Ligands

Kinetics and Mechanisms of Homogeneous Catalytic Reactions. Part 10. Regioselective Hydrogenation of Quinoline Catalyzed by the Systems M2Cl2(COE)4/2 Triphos [M = Rh, Ir; COE = Cyclooctene; Triphos = 1,1,1-Tris(diphenylphosphinomethyl)Ethane]

Kinetics and Mechanisms of Homogeneous Catalytic Reactions. Part 11. Regioselective Hydrogenation of Quinoline Catalyzed by Rhodium Systems Containing 1,2-Bis(diphenylphosphino)ethane

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