Nickel bromide as a hydrogen transfer catalyst

Page, Matthew D. Le; James, Brian R.

doi:10.1039/b005338o

Cited by 65 publications

(29 citation statements)

References 21 publications

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“…[2][3][4][5] One of the advantages of this pathway is that it is performed in the absence of gaseous hydrogen or oxygen, which requires precautions and special high pressure equipment. Although transfer hydrogenation-dehydrogenation is not as highly developed as catalytic hydrogenation or oxidation, it is recognized as an attractive technology with a high potential for wide industrial applicability.…”

Section: Introductionmentioning

confidence: 99%

Glycerol as solvent and hydrogen donor in transfer hydrogenation–dehydrogenation reactions

Wolfson

Dlugy

Shotland

et al. 2009

Tetrahedron Letters

140

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Section: Introductionmentioning

confidence: 99%

Glycerol as solvent and hydrogen donor in transfer hydrogenation–dehydrogenation reactions

Wolfson

Dlugy

Shotland

et al. 2009

Tetrahedron Letters

140

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“…Data for the reduction of respective ketones to alcohol is illustrated in Table 2. Reduction of C@C bond in styrene was not observed when lignin model compound 3,4-dimethoxystyrene was tested as the substrate under analogous hydrogentransfer conditions, further demonstrating general selectivity of [RuH(CO)Cl((j 1 -P-PPh 2 Py) 2 (N-N)] + systems in the reduction of polar C@O bond [8,[23][24][25][65][66][67]. Among the complexes under study, 3 and 7 exhibited highest activity towards hydrogen-transfer hydrogenation of acetophenone (Table 3).…”

Section: Transfer Hydrogenation Of Ketonesmentioning

confidence: 80%

Synthesis and characterization of ruthenium(II) complexes based on diphenyl-2-pyridylphosphine and their applications in transfer hydrogenation of ketones

Kumar

Singh

Yadav

et al. 2011

Inorganica Chimica Acta

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“…The following conditions were used for the data collection: omega and phi scans with exposures taken at 30 W X-ray power and 0.50º frame widths using APEX2. For the counter-ion containing Fe2, the major component of the disordered anion had a site occupancy factor of 0.83 (2); that for the anion containing Fe3 was 0.850 (18). A semi-empirical absorption correction was applied to the data in each case (SADABS 53 ).…”

Section: X-ray Crystallographymentioning

confidence: 99%

“…5 Notably, several Ru(II) complexes are active TH catalysts for ketones, 6 including complexes of the planar tridentate NNNdonor ligands 2-[6-(3,5-dimethyl-1H-pyrazol-1-yl)pyridin-2-yl]-1H-benzimidazole 7 and 2,6-bis(3,5-dimethylpyrazol-1-yl)pyridine. Homogeneous Ni(0) carbene complexes, 15 Ni(0)-based nanoparticles, 16,17 and even NiBr 2 in a binary NaOH-iPrOH mixture 18 are evidently also potentially useful catalysts for the TH of ketones. It is also environmentally unfriendly and is toxic in its ionic form.…”

Section: Introductionmentioning

confidence: 99%

Structural, kinetic, and DFT studies of the transfer hydrogenation of ketones mediated by (pyrazole)pyridine iron(ii) and nickel(ii) complexes

et al. 2016

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A series of iron(II) and nickel(II) complexes chelated by 2-pyrazolyl(methyl)pyridine (L1), 2,6-bis(pyrazolylmethyl)pyridine (L2), and 2,6-bis(pyrazolyl)pyridine (L3) ligands have been investigated as transfer hydrogenation (TH) catalysts for a range of ketones. Nine chelates in total were studied: (8), and [Fe(L3)Cl2] (9). Attempted crystallization of complexes 4 and 6 afforded stable six-coordinate cationic species 4a and 6a with a 2:1 ligand:metal (L:M) stoichiometry, as opposed to the monochelates that function as precursors to catalytic species for TH reactions. Crystallization of 7⋅ ⋅ ⋅ ⋅4H2O and 8⋅ ⋅ ⋅ ⋅2H2O, in contrast, afforded tri-and bis(aqua) salts of L3 chelated to Ni(II) in a 1:1 L:M stoichiometry, respectively. Complexes 1-9 formed active catalysts for TH of a range of ketones in 2-propanol at 82 °C. Both the nature of the metal ion and ligand moiety had a discernible impact on the catalytic activities of the complexes, with nickel(II) chelate 5 affording the most active catalyst (kobs, 4.3 × 10 -5 s -1 ) when the inductive phase lag was appropriately modelled in the kinetics. Iron(II) complex 3 formed the most active TH catalyst without a significant inductive phase lag in the kinetics. DFT and solid angle calculations were used to rationalize the kinetic data: both steric shielding of the metal ion and electronic effects correlating with the metal-ligand distances appear to be significant factors underpinning the reactivity of 1-9. Catalysts derived from 1 and 9 exhibit a distinct preference for aryl ketone substrates, suggesting the possible involvement of π-type catalyst⋅⋅⋅substrate adducts in their catalytic cycles. A catalytic cycle involving only 4 steps (after induction) with stable DFT-simulated structures is proposed which accounts for the experimental data for the system. Please do not adjust marginsPlease do not adjust margins catalysis in the ATH of a series of aromatic ketones using 2propanol as the hydrogen source. 19 Collectively, however,there are comparatively few reports on transfer hydrogenations of ketones in alcohols in the presence of nickel catalysts. As part of our continued investigation of late transition metal-catalysed TH reactions of ketones, 20 we herein report the use of iron(II) and nickel(II) complexes of three (pyrazolyl)pyridine-based ligands as TH catalysts for a range of ketone substrates (compounds 1-9, Scheme 2). Since TH catalysts for ketones typically operate via an induction phase (activation of a precatalyst to an active catalytic species), they are intrinsically difficult to delineate mechanistically, especially when paramagnetic intermediates are involved. We have accordingly attempted to understand some of the structural and electronic factors of the precatalysts that potentially impact on the reactivity of 1-9 using a combination of DFT simulations and solid angle calculations. By combining the information from the experimental kinetics and insights gained from DFT simulations we have proposed a 4-step catalytic cycle (after induction) that accounts ...

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Nickel bromide as a hydrogen transfer catalyst

Cited by 65 publications

References 21 publications

Glycerol as solvent and hydrogen donor in transfer hydrogenation–dehydrogenation reactions

Glycerol as solvent and hydrogen donor in transfer hydrogenation–dehydrogenation reactions

Synthesis and characterization of ruthenium(II) complexes based on diphenyl-2-pyridylphosphine and their applications in transfer hydrogenation of ketones

Structural, kinetic, and DFT studies of the transfer hydrogenation of ketones mediated by (pyrazole)pyridine iron(ii) and nickel(ii) complexes

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