Oxidative Addition of Allylammonium BPh<sub>4</sub><sup>-</sup> to Nickel(0): Synthesis, Crystal Structure, Fluxional Behavior, and Catalytic Activity of Chiral [(<i>η</i><sup>3</sup>-allyl)(NH<sub>3</sub>)(PCy<sub>3</sub>)Ni]BPh<sub>4</sub>
in the solid state and in solution. The X-ray study shows that the cation [(η3-C3H5)Ni(PCy3)(NH3)]+ (1+) is chiral as a result of the two possible orientations of the allyl group and the different ancillary ligands bound to the (η3-C3H5)Ni+ moiety. In the solid state, cation 1+ exists as a racemic mixture of the two enantiomers 1a+ and 1b+. In solution, complex 1+ is involved in a slow fluxional process
Reactivity of ammonium and iminium tetraphenylborates towards Pd(0)-complexes: selective allyl or proton transfer to Pd(0).
作者:Michele Aresta、Eugenio Quaranta
DOI:10.1016/s0022-328x(02)01897-1
日期:2002.11
The reactivity of ammonium- and iminium-BPh4 Salts, [CH2=CHCH2NH3]BPh4, [(CH2=CHCH2)HN=CMe2]BPh4 and [(PhCH2)HN=CMe2]BPh4, towards Pd(0)-complexes, [Pd(dppe)(dba)] and [Pd(dppe)(2)] (dppe = 1,2-bis(diphenylphosphino)ethane; dba = dibenzylideneacetone), has been investigated. Allyl-ammonium and -iminium tetraphenylborates [CH2=CHCH2NH3]BPh4 and [(CH2=CHCH2)HN=CMe2]BPh4 react with [Pd(dppe)(dba)] to afford, under mild conditions (293 K), [(eta(3)-C3H5)Pd(dppe)][BPh4], through selective oxidative transfer of allyl group from the ammonium or iminium cation to the Pd center. [(PhCH2)HN CMe2]BPh4 reacts with [Pd(dppe)(2)] to afford [H-Pd(dppe)(2)][BPh4], that, under the reaction conditions, has poor stability as it undergoes hydride transfer to the iminium ion present in the reaction medium, affording [Pd(dppe)(2)][BPh4](2). (C) 2002 Elsevier Science B.V. All rights reserved.
Oxidative Addition of Ammonium and Iminium Tetraphenylborates to Low-Valent Metal Complexes. Evidence of Selective N−C and N−H Activation. A New, Easy Route to Cationic Allyl- and Hydridonickel Complexes
The reaction of ammonium and iminium tetraphenylborate salts ((CH2CHCH2NH3)BPh4, [(CH2CHCH2)HNCMe2]BPh4, and [(PhCH2)HNCMe2]BPh4) with transition-metal systems in a low oxidation state has been investigated. We report the oxidative addition to (Cy3P)2Ni(η2-CO2) or (Cy3P)2NiN⋮NNi(PCy3)2 under mild conditions (253−293 K) and describe a very selective NC or NH bond activation. (CH2CHCH2NH3)BPh4 or [(