Acid−Base Reactions of Methylnickel Hydroxo, Alkoxo, and Amide Complexes with Carbon Acids. Studies on the Reactivity of Noncyclic Nickel Enolates
datasetposted on 07.05.2020, 10:03 by Juan Cámpora, Inmaculada Matas, Pilar Palma, Eleuterio Álvarez, Claudia Graiff, Antonio Tiripicchio
Basic organonickel hydroxo, alkoxo, or amido complexes of composition Ni(Me)(X)(dippe) (X = OH, t-BuO, cyclo-NC4H8; dippe = i-Pr2PCH2CH2Pi-Pr2) react with enolizable ketones, esters, and nitriles, producing the corresponding enolate complexes. In the case of the hydroxo and alkoxo complexes, these reactions may lead to equilibrium mixtures, allowing a comparison of their respective basicities, while the amido compound reacts clean and quantitatively in all cases, allowing the isolation of the corresponding enolates. While the ketone derivatives display oxygen-bound enolate ligands, the ester and nitrile enolates bind the metal center through the carbon atom. The acetophenone enolate complex has strong nucleophilic properties and rapidly reacts with aldehydes (PhCHO) or CO2, affording the corresponding aldolate and carboxylate addition products.
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enolizable ketonesAmide ComplexesOHketone derivatives display oxygen-bound enolate ligandscarbon atomCO 2alkoxo complexesNoncyclic Nickel Enolates Basic organonickel hydroxocarboxylate addition productsPr 2 PCH 2 CH 2 P iequilibrium mixturesnucleophilic propertiesacetophenone enolateamido compoundnitrile enolates bindenolate complexesamido complexesPr 2NC 4 H 8Carbon AcidsMethylnickel Hydroxometal center