RESUMO
The mol-ecular structure of the title complex, [Ni(C13H8F2N2O)(C14H32P2)] or Ni(oFPU)(dippe), where oFPU is the dianion of bis-(2-fluoro-phen-yl)urea and dippe is 1,2-bis-(di-iso-propyl-phosphino)ethane, comprises an NiII atom with a distorted square-planar coordination environment (geometry index τ4 = 0.195). One of the fluoro-phenyl rings of the oFPU ligand is disordered over two sets of sites in an 0.832â (7):0.168â (7) ratio. The crystal structure displays C-Hâ¯O and C-Hâ¯F hydrogen-bonding inter-actions, leading to chains with R 2 2(12) motifs extending parallel to [100]. The title compound might be of inter-est with respect to the production of urea and carbamate derivatives of nickel(II).
RESUMO
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.
RESUMO
The use of nickel compounds in low oxidation states allowed a variety of useful transformations of interest for academia, industry and in the solution of environmental issues.
RESUMO
Ni(0)-catalyzed dehydrogenation of benzylic-type imines was performed to yield asymmetrical tetra-substituted imidazoles and 2-imidazolines. This was achieved with a single operational step while maintaining good selectivity and atom economy. The catalytic system shows low to moderate tolerance for fluoro-, trifluoromethyl-, methyl-, and methoxy-substituted benzylic-type imines. In addition, the substitution pattern at the N-heterocyclic products was easily controlled by the appropriate selection of R-groups in the starting organic substrates. Based on experimental observations, we propose a reaction mechanism in which benzylic C(sp(3))-H bond activation and insertion steps play pivotal roles in this nickel-catalyzed organic transformation.