5814-85-7Relevant articles and documents
Characterization and reactivity studies of dinuclear iridium hydride complexes prepared from iridium catalysts with N,P and C,N ligands under hydrogenation conditions
Gruber, Stefan,Neuburger, Markus,Pfaltz, Andreas
, p. 4702 - 4711 (2013)
The dinuclear iridium hydride complexes [IrH(CH3CN)(L1)(μ-H)] 2(BArF)2 (7; L1 = (S)-2-(2- ((diphenylphosphanyl)oxy)propan-2-yl)-4-isopropyl-4,5-dihydrooxazole, BAr F = tetrakis[3,5-bis(trifluoromethyl)phenyl]borate), [IrH(CH 2Cl2)(L1)(μ-H)]2(BArF) 2 (8), [IrH(L2)(μ-H)]2(BArF)2 (9a; L2 = (S)-1-[2-(2-adamantan-2-yl-4,5-dihydrooxazol-4-yl)-ethyl]-3-(2,6- diisopropylphenyl)-1,2-dihydroimidazol-2-ylidene), and [IrH(L3)(μ-H)] 2(BArF)2 (9b; L3 = (S)-1-[2-(2-tert-butyl-4,5- dihydrooxazol-4-yl)-ethyl]-3-(2,6-diisopropylphenyl)-1,2-dihydroimidazol-2- ylidene) were prepared from the corresponding mononuclear [Ir(COD)(L)]BAr F precursors by treatment with H2 and characterized by 2D NMR spectroscopy and X-ray diffraction. Conversion to a trinuclear iridium hydride complex, which is usually observed for N,P iridium hydride complexes, is inhibited by addition of 0.5 equiv of [H(OEt2)2]BAr F or acetonitrile. Reactions with acetonitrile or 6,6′-bi-2-picoline afforded the mononuclear iridium dihydride complexes [Ir(H)2(CH3CN)2(L1)]BArF (5), [Ir(H)2(CH3CN)2(L3)]BArF (10), or [Ir(H)2(6,6′-bi-2-picoline)(L3)]BArF (11). The CH3CN complexes 7 and 10 are inactive as hydrogenation catalysts. In contrast, the coordinatively unsaturated dinuclear complexes 9a and 9b are active catalysts for the hydrogenation of (E)-1,2-diphenyl-1-propene at 50 bar hydrogen pressure.
Merging Halogen-Atom Transfer (XAT) and Copper Catalysis for the Modular Suzuki-Miyaura-Type Cross-Coupling of Alkyl Iodides and Organoborons
Zhang, Zhenhua,Górski, Bartosz,Leonori, Daniele
, p. 1986 - 1992 (2022/02/01)
We report here a mechanistically distinct approach to achieve Suzuki-Miyaura-type cross-couplings between alkyl iodides and aryl organoborons. This process requires a copper catalyst but, in contrast with previous approaches based on palladium and nickel
Boosting homogeneous chemoselective hydrogenation of olefins mediated by a bis(silylenyl)terphenyl-nickel(0) pre-catalyst
Lücke, Marcel-Philip,Yao, Shenglai,Driess, Matthias
, p. 2909 - 2915 (2021/03/14)
The isolable chelating bis(N-heterocyclic silylenyl)-substituted terphenyl ligand [SiII(Terp)SiII] as well as its bis(phosphine) analogue [PIII(Terp)PIII] have been synthesised and fully characterised. Their reaction with Ni(cod)2(cod = cycloocta-1,5-diene) affords the corresponding 16 VE nickel(0) complexes with an intramolecularη2-arene coordination of Ni, [E(Terp)E]Ni(η2-arene) (E = PIII, SiII; arene = phenylene spacer). Due to a strong cooperativity of the Si and Ni sites in H2activation and H atom transfer, [SiII(Terp)SiII]Ni(η2-arene) mediates very effectively and chemoselectively the homogeneously catalysed hydrogenation of olefins bearing functional groups at 1 bar H2pressure and room temperature; in contrast, the bis(phosphine) analogous complex shows only poor activity. Catalytic and stoichiometric experiments revealed the important role of the η2-coordination of the Ni(0) site by the intramolecular phenylene with respect to the hydrogenation activity of [SiII(Terp)SiII]Ni(η2-arene). The mechanism has been established by kinetic measurements, including kinetic isotope effect (KIE) and Hammet-plot correlation. With this system, the currently highest performance of a homogeneous nickel-based hydrogenation catalyst of olefins (TON = 9800, TOF = 6800 h?1) could be realised.
