New nickel-containing homogeneous hydrogenation catalysts

Angulo, Ingrid M.; Bouwman, Elisabeth; Gorkum, Remy van; Lok, Sandra M.; Lutz, Martin; Spek, Anthony L.

doi:10.1016/s1381-1169(03)00216-4

Cited by 38 publications

(32 citation statements)

References 12 publications

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“…The structures of the complexes [Pd(L1)OAc 2 ], [30] [Pd(L2)Cl 2 ] and [Pd(L7)Cl 2 ], [31] as well as of the analogous nickel(II) complexes [Ni(L2)I 2 ] [26] and [Ni(L7)Cl 2 ] [32] have been published; the reported distances, angles and Pd···H or Ni···H interactions are comparable to those described above.…”

Section: Complex Structures In the Solid Statesupporting

confidence: 59%

NMR Spectroscopic Studies of Palladium(II) Complexes of Bidentate Diphenylphosphane Ligands with Acetate and Tosylate Anions: Complex Formation and Structures

et al. 2010

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The synthetic pathways towards PdII complexes of functionalized bidentate diphenylphosphane ligands of the type [Pd(ligand)(anion)2] and [Pd(ligand)2](anion)2 have been investigated. Eighteen different ligands have been used in combination with strongly (acetate, OAc–) or weakly (tosylate, OTs–) coordinating anions. The solid‐state structure of some representative complexes was determined with X‐ray crystallography. It is shown that the solid‐state structures are fully retained in solution. The formation of [Pd(ligand)(anion)2]‐type complexes was studied in detail by 1H‐ and 31P‐NMR spectroscopy. Depending on the ligand structure, the complex is formed instantaneously, via a polynuclear intermediate or is not formed at all. Complex formation is demonstrated to depend on the length and rigidity of the ligand backbone and on the steric bulk at the ortho position of the phenyl rings on phosphorus. It was also found that the coordinating ability of the anions can alter the structure of the kinetic and/or thermodynamic product.

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Section: Complex Structures In the Solid Statesupporting

confidence: 59%

NMR Spectroscopic Studies of Palladium(II) Complexes of Bidentate Diphenylphosphane Ligands with Acetate and Tosylate Anions: Complex Formation and Structures

et al. 2010

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“…Ethene bubbling into CH 2 Cl 2 solutions of the acyl complexes 3b and 4b for 2 min, followed by the addition of stoichiometric NaBArЈ 4 , gave the β-keto chelates 3c and 4c (Scheme 4). Compounds 3b, 3c, 4b, and 4c have been unambiguously characterized by variable-temperature 31 P{ 1 H} and 1 H NMR spectroscopy.…”

Section: Thementioning

confidence: 99%

“…[2d, [3][4][5] In the light of the kinetic and thermodynamic data relative to the opening of the β-chelate ring by CO and to the alkyl migration to CO (Table 7), one may safely conclude that the latter process (step c of Scheme 8) limits the overall rate of the transformation of 3c and 4c into the (acyl)carbonyl products 3g and 4g, which is a relevant step in the propagation mechanism of the CO/ethene copolymerization by Pd II -diphosphane catalysis. [1] Accordingly, since the Pd(CO)alkyl migratory insertion is independent of the CO pressure (vide infra), the overall copolymerization process would be independent of the CO pressure, at least under a gas pressure of 20 bar.…”

Section: Carbonylation Reactions Of the β-Keto Chelatesmentioning

confidence: 99%

“…The IR values of the CO stretching frequencies are reported in Table 4. 4 . HPNMR Experiments: CD 2 Cl 2 (2 mL) solutions of the β-keto chelates [Pd(CH 2 CH 2 C(O)Me)(P-P)]BArЈ 4 (P-P = oMeO-dppe, 3c; o-MeO-dppp, 4c) (0.03 mmol) were synthesized in situ in a Schlenk tube at -30°C, as described above.…”

Section: In Situ Generation and Migratory Insertion Barriers Of [Pdmementioning

confidence: 99%

“…[2d,3] Both steric and electronic factors have been invoked to account for the positive effect of the o-methoxy groups on the catalyst activity, yet no clear-cut explanation has been put forward so far. Indeed, most of the previous hypotheses are based on indirect observations such as the decreased formation of catalytically inactive bis-chelates or binuclear species; [4] the reduced tendency towards phosphane oxi-phosphanyl)ethane (dppe) and 1,3-bis(diphenylphosphanyl)-propane (dppp) ligands. It was found that o-MeO substituents on the phosphorus aryl rings ease the opening of the β-chelate ring by CO and affect the kinetics of the overall CO/ ethene copolymerization.…”

Section: Introductionmentioning

confidence: 99%

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Unraveling the o‐Methoxy Effect in the CO/Ethene Copolymerization Reaction by Diphosphanepalladium(II) Catalysis

et al. 2007

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Relevant steps in the CO/ethene copolymerization reaction, namely the migratory insertion of [Pd(Me)(CO)(P-P)]BArЈ 4 and the carbonylation of the β-keto chelates [Pd(CH 2 CH 2 C(O)Me)(P-P)]BArЈ 4 have been studied by in situ high-pressure NMR spectroscopy in CH 2 Cl 2 ; P-P = 1,2-bis[bis(2-methoxyphenyl)phosphanyl]ethane or 1,3-bis[bis(2-methoxyphenyl)phosphanyl]propane. This study, backed by batch catalytic reactions in the same solvent, has contributed to rationalizing the higher catalytic activity of Pd II catalysts modified with o-methoxy-substituted diphosphane ligands as compared to analogous Pd II catalysts with 1,2-bis(diphenyl-

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Nickel

Bouwman¹

2006

The Handbook of Homogeneous Hydrogenation

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Nickelneous hydrogenation reaction. In this section, a brief overview will be provided of mononuclear nickel complexes, which have been reported to catalyze homogeneously the hydrogenation of various olefins. Many of the reported nickel-containing hydrogenation catalysts are of the Ziegler type (i.e., a nickel salt in combination with a reducing agent such as trialkylaluminum), and in many cases it is questionable whether the reported complexes yield really homogeneous hydrogenation catalysts or that the observed catalytic hydrogenation activity is due to formation of colloidal (heterogeneous) nickel particles [5]. Coordination Chemistry and Organometallic Aspects of Nickel Nickel-Hydride Complexes Nickel 94Scheme 5.1 Different modes of dihydrogen activation. (a) Oxidative addition, forming a metal dihydride species; (b) homolytic activation, forming two metal monohydride species; (c) heterolytic splitting, forming a metal hydride species and a proton.

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New nickel-containing homogeneous hydrogenation catalysts

Cited by 38 publications

References 12 publications

NMR Spectroscopic Studies of Palladium(II) Complexes of Bidentate Diphenylphosphane Ligands with Acetate and Tosylate Anions: Complex Formation and Structures

NMR Spectroscopic Studies of Palladium(II) Complexes of Bidentate Diphenylphosphane Ligands with Acetate and Tosylate Anions: Complex Formation and Structures

Unraveling the o‐Methoxy Effect in the CO/Ethene Copolymerization Reaction by Diphosphanepalladium(II) Catalysis

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