40438-65-1Relevant academic research and scientific papers
Palladium nanocatalysts in glycerol: Tuning the reactivity by effect of the stabilizer
Reina, Antonio,Serrano-Maldonado, Alejandro,Teuma, Emmanuelle,Martin, Erika,Gómez, Montserrat
, p. 22 - 27 (2017/10/24)
Palladium nanoparticles (PdNPs) prepared in neat glycerol containing TPPTS (tris(3-sulfophenyl)phosphine trisodium salt) or cinchona-based alkaloids (cinchonidine, quinidine) as capping agents, were applied as catalysts in fluoride-free Hiyama couplings and conjugate additions with the aim of evaluating the influence of the stabilizer in the catalytic reactivity. Therefore, PdNPs stabilized by phosphine favored C–C cross-couplings, whereas those containing alkaloids showed enhanced suitability for C–C homo-couplings and conjugate additions. The metal/stabilizer coordination mode, i.e. Pd–P dative bond and π-π interaction between quinoline moiety and palladium surface, is certainly key for the stabilization of different active metallic species and then promoting distinctive catalytic pathways.
Inner- and Outer-Sphere Roles of Ruthenium Phosphido Complexes in the Hydrophosphination of Alkenes
Belli, Roman G.,Burton, Krista M. E.,Rufh, Stephanie A.,McDonald, Robert,Rosenberg, Lisa
supporting information, p. 5637 - 5646 (2015/12/23)
An inner-sphere synthetic cycle for the hydrophosphination of alkenes is proposed, based on observed [2 + 2] cycloaddition of a wide range of alkenes at a coordinatively unsaturated Ru=PR2 complex. Key intermediates in the cycle were prepared, and their reactions with various organic acid/base pairs were examined to identify both new ruthenium precursors and base cocatalysts that allow turnover of the proposed cycle. Two new cationic ruthenium indenyl phosphine complexes were isolated and structurally characterized. Although preliminary screening studies show the moderate activity of these and related neutral phosphido complexes for catalytic hydrophosphination of acrylonitrile by both HPPh2 and HPCy2, and comparable activity for the hydrophosphination of tert-butyl acrylate by HPPh2, no activity was observed for the analogous hydrophosphination of 1-hexene. This is attributed to strong binding of the substrate phosphine to the unsaturated, planar Ru - PR2 fragment generated in situ, which inhibits the inner-sphere, alkene cycloaddition mechanism. An alternative, outer-sphere Michael addition process, involving a saturated complex with a strongly nucleophilic pyramidal Ru-PR2 ligand, is proposed to rationalize the observed selectivity for catalytic hydrophosphination of activated, but not simple, alkenes. Implications for further catalyst development are discussed.
