24476-86-6Relevant academic research and scientific papers
Comprehensive Study of the Reactions between Chelating Phosphines and Ni(cod)2
Clevenger, Andrew L.,Stolley, Ryan M.,Staudaher, Nicholas D.,Al, Noman,Rheingold, Arnold L.,Vanderlinden, Ryan T.,Louie, Janis
, p. 3259 - 3268 (2018/09/12)
A comprehensive study of the reactions of chelating phosphines with Ni(cod)2 to form (phosphine)Ni(cod), (phosphine)2Ni, or mixtures thereof is presented. A series of (phosphine)Ni(cod) complexes were isolated and characterized. The structural differences between the (phosphine)Ni(cod) and (phosphine)2Ni complexes were examined using X-ray crystallography and 1H and 31P NMR spectroscopy. In addition, the effects of ring size, rigidity, and bulk of the phosphine backbone on the formation of either (phosphine)Ni(cod) or (phosphine)2Ni were investigated. These studies show that the Ni-P bond lengths in both the (phosphine)Ni(cod) and (phosphine)2Ni complexes and the size of the ring formed by the chelating phosphine and Ni are crucial in determining whether or not (phosphine)Ni(cod) complexes can be isolated. Other factors such as π-stacking interactions were found to have marginal influence.
Monomeric three-coordinate N-heterocyclic carbene nickel(I) complexes: Synthesis, structures, and catalytic applications in cross-coupling reactions
Matsubara, Kouki,Fukahori, Yukino,Inatomi, Takahiro,Tazaki, Saeko,Yamada, Yuji,Koga, Yuji,Kanegawa, Shinji,Nakamura, Toshikazu
supporting information, p. 3281 - 3287 (2016/10/21)
A series of three-coordinate monovalent nickel halide complexes bearing N-heterocyclic carbene (NHC) ligands, i.e., NiCl(IPr)(L) [L = pyridine, P(OPh)3, bis(diphenylphosphino)butane (dppb), IPr = 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene], NiX(IMes)(PPh3) (X = Cl and Br, IMes = 1,3-bis(mesityl)imidazol-2-ylidene), were prepared. The complexes were identified using NMR spectroscopy, superconducting quantum interference device (SQUID), and X-ray crystallography. Additionally, ESR spectra of NiCl(IPr)(pyridine) were taken in toluene. These complexes had three-coordinate Y-shaped geometries in both the solid and solution states. The compounds containing IPr showed equilibrium between the monomeric and dimeric forms, with liberation of ligands. Addition of 1,2-bis(diphenylphosphino)ethane and 1,3-bis(diphenylphosphino)propane to the dinickel(I) IPr complex instead of dppb resulted in heterolytic cleavage to nickel(0) and nickel(II) species. Catalysis of Suzuki cross-coupling and Buchwald-Hartwig amination of aryl bromide using the complexes was investigated. The efficiencies in the amination of aryl bromide depended strongly on the additional donor ligands.
Preparation of benzyne complexes of group 10 metals by intramolecular Suzuki coupling of ortho-metalated phenylboronic esters: Molecular structure of the first benzyne-palladium(0) complex
Retboll, Mikael,Edwards, Alison J.,Rae, A. David,Willis, Anthony C.,Bennett, Martin A.,Wenger, Eric
, p. 8348 - 8360 (2007/10/03)
A series of nickel(II) and palladium(II) aryl complexes substituted in the ortho position of the aromatic ring by a (pinacolato)boronic ester group, [MBr{o-C6H4B(pin)}L2] (M = Ni, L2 = 2PPh3 (2a), 2PCy3 (2b), 2PEt3 (2c), dcpe (2d), dppe (2e), and dppb (2f); M = Pd, L2 = 2PPh3 (3a), 2PCy3 (3b), and dcpe (3d)), has been prepared. Many of these complexes react readily with KOtBu to form the corresponding benzyne complexes [M(η2-C6H4)L2] (M = Ni, L2 = 2PPh3 (4a), 2PCY3 (4b), 2PEt3 (4c), dcpe (4d); M = Pd, L2 = 2PCy3 (5b)). This reaction can be regarded as an intramolecular version of a Suzuki cross-coupling reaction, the driving force for which may be the steric interaction between the boronic ester group and the phosphine ligands present in the precursors 2 and 3. Complex 3d also reacts with KOtBu, but in this case disproportionation of the initially formed η2-C6H4 complex (5d) leads to a 1:1 mixture of a novel dinuclear palladium(I) complex, [(dcpe)Pd(μ2-C6H4)Pd(dcpe)] (6), and a 2,2′-biphenyldiyl complex, [Pd(2,2′-C6H4C6H4)-(dcpe)] (7d). Complexes 2a, 3b, 3d, 4b, 5b, 6, and 7d have been structurally characterized by X-ray diffraction; complex 5b is the first example of an isolated benzyne-palladium(0) species.
Homogeneous and biphasic nickel-catalyzed isomerization of allylic alcohols
Bricout, Herve,Monflier, Eric,Carpentier, Jean-Francois,Mortreux, Andre
, p. 1739 - 1744 (2008/10/08)
The nickel-catalyzed isomerization of geraniol and prenol in homogeneous and two-phase systems has been investigated. The best results in terms of activity and selectivity have been obtained in homogeneous systems with a bis(cycloocta-1,5-diene)nickel(0)/1,4-bis(diphenylphosphanyl)butane/ trifluoroacetic acid combination. Catalyst deactivation occurs in the course of the reaction owing to coordination of the formed aldehyde group to the nickel species or as a result of protonolysis of hydrido- or (π-allyl)nickel complexes.
Nickel-catalysed Substitution Reactions of Allylic Compounds with Soft Nucleophiles: an Efficient Alternative to Palladium Catalysis
Bricout, Herve,Carpentier, Jean-Francois,Mortreux, Andre
, p. 1863 - 1864 (2007/10/02)
Substitution reactions of allyl alcohol derivatives 1a-c with diethylamine, phenol and dimethyl malonate are efficiently carried out in the presence of Ni(dppb)2 (dppb = 1,2-diphenylphosphinobutane) as catalyst and ammonium salts or bases as promoters or co-reagents.
Effect of the Bite Angle of Diphosphine Ligands on Activity and Selectivity in the Nickel-catalysed Hydrocyanation of Styrene
Kranenburg, Mirko,Kamer, Paul C. J.,Leeuwen, Piet W. N. M. van,Vogt, Dieter,Keim, Wilhelm
, p. 2177 - 2178 (2007/10/02)
The application of diphosphines with large bite angles (βn = 101-109 deg) in nickel catalysts leads to successful, regioselective hydrocyanation of styrene.
LIGAND EXCHANGE REACTION BETWEEN NiMe2L2 (L = 1/2 bpy, PEt3) AND DITERTIARY PHOSPHINES Ph2P(CH2)nPPh2 (n = 1-4) AND EFFECT OF LIGAND ON EASE OF REDUCTIVE ELIMINATION OF C2H6 FROM NiMe2(Ph2P(CH2)nPPh2)
Kohara, Teiji,Yamamoto, Takakazu,Yamamoto, Akio
, p. 265 - 274 (2007/10/02)
Reactions of the dimethylnickel(II) complexes NiMe2L2 (L = 1/2 bpy, PEt3 (bpy=2,2'-bipyridine)) with diphosphines Ph2P(CH2)nPPh2 (n = 1-4) give NiMe2(Ph2P(CH2)nPPh2) (n = 2, 3) or produce ethane and Ni0-diphosphine complexes (n = 1, 4), depending on the chain length of (CH2)n of the diphosphine ligand employed.The ligand exchange reaction between NiMe2(bpy) and Ph2P(CH2)3PPh2 (dpp) proceeds through an SN2 process with the activation parameters ΔH = 8.3 kcal/mol and ΔS = -35 e.u.A mechanism involving coordination of dpp via one phosphorus atom and ensuing chelation of dpp accompanied by dissociation of bpy is proposed for the ligand exchange reaction.Kinetic studies on the thermal decomposition of NiMe2(Ph2P(CH2)nPPh2) (n = 2, 3) show that the reductive elimination of C2H6 from NiMe2(Ph2P(CH2)nPPh2) (n = 2, 3) proceeds by a unimolecular process with the activation parameters ΔH = 26.8 kcal/mol and ΔS = 1.9 e.u. for NiMe2(Ph2P(CH2)2PPh2) and ΔH = 25.1 kcal/mol and ΔS = 4.8 e.u. for NiMe2(Ph2P(CH2)3PPh2).The rate of reductive elimination of NiMe2(Ph2P(CH2)3PPh2) is 46 times faster than that of NiMe2(Ph2P(CH2)2PPh2) at 64.3 deg C.
