115223-08-0Relevant articles and documents
Nickelalactones with an allyl subunit-the effect of penta-coordination on structures and stability
Freund, Robert R. A.,Goerls, Helmar,Langer, Jens
, p. 13988 - 14000 (2014)
A series of allyl modified nickelalactone derivatives of the general formula [(L)nNi{CH2C(CH3)C(CH 3)CH2COO}] was synthesized via ligand exchange reactions in order to investigate the influence of the neutral ligand L on the structure and stability of these complexes. While the square planar 1,8-diazabicyclo[5,4, 0]undec-7-ene ligated derivative 1 is stable in the solid state and in solution at ambient temperature, the use of the chelating ligands 6-diphenylphosphino-1, 8-diazabicyclo[5.4.0]undec-7-ene, 1,1-bis(dicyclohexylphosphino)methane and 1,2-bis(dicyclohexylphosphino)ethane (dcpe) led to square pyramidal derivatives 2, 4, and 5 with a novel ligand arrangement. In solution, these derivatives are fluxional and show increasing tendencies in the order 2 2 and zero-valent nickel complexes. During the investigation of 5, the tetrahedral complex [(dcpe)2Ni] (6) and the trigonal planar derivative [(dcpe)Ni(dmbd)] (7) were observed as predominant decomposition products. In the case of the application of 1,1-bis(diphenylphosphino)methane as a neutral ligand, a dinuclear nickelalactone species [(μ-dppm)(Ni{CH 2C(CH3)C(CH3)CH2COO})2] (3) was isolated in which the two nickel atoms realize different coordination geometries (SP-4 and SPY-5) in the solid state. The complexes were characterized by NMR techniques, single crystal X-ray diffraction measurements and infrared spectroscopy.
Nickel-Catalyzed Amination of Aryl Thioethers: A Combined Synthetic and Mechanistic Study
Bismuto, Alessandro,Delcaillau, Tristan,Müller, Patrick,Morandi, Bill
, p. 4630 - 4639 (2020/05/19)
Herein, we report a nickel-1,2-bis(dicyclohexylphosphino)ethane (dcype) complex for the catalytic Buchwald-Hartwig amination of aryl thioethers. The protocol shows broad applicability with a variety of different functional groups tolerated under the catalytic conditions. Extensive organometallic and kinetic studies support a nickel(0)-nickel(II) pathway for this transformation and revealed the oxidative addition complex as the resting state of the catalytic cycle. All the isolated intermediates have proven to be catalytically and kinetically competent catalysts for this transformation. The fleeting transmetalation intermediate has been successfully synthesized through an alternative synthetic organometallic pathway at lower temperature, allowing for in situ NMR study of the C-N bond reductive elimination step. This study addresses key factors governing the mechanism of the nickel-catalyzed Buchwald-Hartwig amination process, thus improving the understanding of this important class of reactions.
Nickel-catalyzed transfer hydrogenation of ketones using ethanol as a solvent and a hydrogen donor
Castellanos-Blanco, Nahury,Arévalo, Alma,García, Juventino J.
, p. 13604 - 13614 (2016/09/04)
We report a nickel(0)-catalyzed direct transfer hydrogenation (TH) of a variety of alkyl-aryl, diaryl, and aliphatic ketones with ethanol. This protocol implies a reaction in which a primary alcohol serves as a hydrogen atom source and solvent in a one-pot reaction without any added base. The catalytic activity of the nickel complex [(dcype)Ni(COD)] (e) (dcype: 1,2-bis(dicyclohexyl-phosphine)ethane, COD: 1,5-cyclooctadiene), towards transfer hydrogenation (TH) of carbonyl compounds using ethanol as the hydrogen donor was assessed using a broad scope of ketones, giving excellent results (up to 99% yield) compared to other homogeneous phosphine-nickel catalysts. Control experiments and a mercury poisoning experiment support a homogeneous catalytic system; the yield of the secondary alcohols formed in the TH reaction was monitored by gas chromatography (GC) and NMR spectroscopy.
Successive insertion of tetrafluoroethylene and CO and of tetrafluoroethylene and acetylenes into aryne-nickel(0) bonds
Bennett, Martin A.,Glewis, Margaret,Hockless, David C. R.,Wenger, Eric
, p. 3105 - 3114 (2007/10/03)
Aryne-nickel complexes [Ni(η2-C6H4)L2] [L2 = 2PEt3 or dcpe; dcpe = (C6H11)2PCH2CH2P(C 6H11)2] and [Ni(η2-C10H6)(PEt3)2] reacted readily with C2F4 to form the corresponding five-membered tetrafluoro-substituted nickelacycles [Ni(C6H4CF2CF2-2)L2] (L2 = dcpe or 2PEt3) and [Ni(2-C10H6CF2CF2-3)(PEt 3)2], respectively. The complex [Ni(C6H4CF2CF2-2)(dcpe)] is very stable towards air, whereas the PEt3 analogues react readily to give μ-aryloxo dimers. The naphthalene-based dimer [{Ni(μ-2-OC10H6CF2CF2-3)(PEt 3)}2] has been structurally characterized. The complexes [Ni(C6H4CF2CF2-2)L2] insert CO into their aryl-nickel bonds to form six-membered acyl complexes [Ni{C(O)C6H4CF2CF2-2} L2] (L2 = dcpe or 2PEt3) and, after CO-induced reductive elimination, 2,2,3,3-tetrafluoroindanone. The dcpe acyl complex has also been shown to undergo reaction with air to form the carboxylato complex [Ni{OC(O)C6H4CF2CF2-2}(dcpe)], whose structure has been confirmed by X-ray crystallography. Some insertions of acetylenes into the aryl-nickel bonds of [Ni(C6H4CF2CF2-2)L2] are also reported.
Synthesis and reactions of nickel(0) η2-cyclohexyne complexes and X-ray crystal structure of Ni(η2-C6H8)(C6H 11)2PCH2CH2P(C6H 11)2
Bennett, Martin A.,Johnson, Julian A.,Willis, Anthony C.
, p. 68 - 74 (2008/10/08)
Reduction of 1,2-dibromocyclohexene with 1% sodium amalgam in the presence of Ni(η2-C2H4)L2 gives cyclohexyne nickel(O) complexes Ni(η2-C6H8)L2 [L2 = 2PPh3 (1), dcpe (2), 2PEt3 (3); dcpe = 1,2-bis(dicyclohexylphosphino)ethane, Cy2PCH2CH2PCy2], which are structurally similar to, but less stable than, the corresponding platinum(O) compounds. The crystal structure of 2 has been determined. The molecule contains a nickel atom bound to η2-cyclohexyne [Ni-C(1) = 1.875(4) A?, Ni-C(2) = 1.867(4) A?] and to dcpe [Ni-P(1) = 2.139-(1) A?, Ni-P(2) = 2.138(1) A?]. The geometry is close to trigonal planar if the midpoint of the coordinated triple bond is regarded as occupying one coordination site, and the C=C distance [1.272(5) A?] is slightly less than that in Pt(η2-C6H8)(PPh3)2 [1.297(8) A?]. Complex 2 reacts with methyl iodide and with CO2 to give insertion products containing nickel(II), NiI(2-MeC6H8)(dcpe) (7) and Ni{C6H8C(O)O}(dcpe)(9), respectively. Dimethyl acetylenedicarboxylate inserts into the Ni-C σ-bond of 9 to give a seven-membered nickelacycle Ni{C(CO2-Me)=C(CO2Me)C6H 8C(O)C-(dcpe) (10).
Reactivity of Nickel(II) Diphosphine Complexes towards Alkoxides: a New Route to the Synthesis of Nickel(0) Compounds through Nickel(II) Alkoxides
Sacco, Adriano,Mastrorilli, Pietro
, p. 2761 - 2764 (2007/10/02)
Reaction of with NaOR (R = Me, Et or i-Pr) under a dinitrogen atmosphere afforded , Ni(OR)2 and aldehyde (or acetone when R = Pri) in 1:1:1 ratio, showing the peculiar reducing effect of alkoxide promoted by the chelating property of the phosphorus ligand.The reaction of NaOMe with afforded mainly when carried out in the absence of free diphosphine, and in the presence of free diphosphine.The reaction always yields the nickel(0) species when it is carried out under a carbon monoxide atmosphere.The intermediate formation of unstable alkoxo(diphosphine)nickel(II) complexes has been demonstrated by recording the 31P NMR spectra of the reactiong solutions at low temperature; in the case of the reaction of with NaOMe only, it was possible to isolate as a solid the complex, which has been fully characterized by analytical and spectroscopic (IR and 1H, 31P NMR) methods.A possible route by which nickel(0) complexes could be formed is discussed.
