Browsing by Author "Matute, Ricardo A."

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    Bulky and Electron-Deficient α-Iminocarboxamidato-Nickel(II) Complexes: A Study of the Steric and Electronic Effects on Ethylene Activation
    (2021) Skarjan, Leon; Villegas-Escobar, Nery; Correa, Sebastian A.; Daniliuc, Constantin G.; Matute, Ricardo A.; Rojas, Rene S.
    Two alpha-iminocarboxamidato-nickel(II) complexes containing ligands with several CF3 groups were synthesized and characterized by NMR spectroscopy, elemental analysis, and density functional theory (DFT) calculations. Surprisingly, the prepared complexes were inactive toward ethylene oligo/polymerization reactions upon activation attempts with common lewis acid co-catalysts such as B(C6F5)(3) and BF3. Quantum chemistry calculations were employed to reveal that adduct formation is thermodynamically favored for small Lewis acids such as BF3 due to the sterically demanding ligand environment of the complex, confirming the experimental findings. DFT results associate the lack of polymerization activity with a highly unfavorable steric environment, undesirable London dispersion interactions between the ligands, and a strong electrostatic stabilization caused by the employed ligands. Our findings should help future researchers to identify necessary electronic and steric requirements for the compounds to generate active Ni(II) catalysts for ethylene oligo/polymerization activated by suitable boron Lewis acids.
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    Reaction Electronic Flux Perspective on the Mechanism of the Zimmerman Di-π-methane Rearrangement
    (2018) Matute, Ricardo A.; Villegas, Nery Andrés; Herrera Pisani, Bárbara Andrea; Gutiérrez Oliva, Soledad; Toro Labbé, Alejandro; Pérez, Patricia; Chamorro, Eduardo; Cortés Arriagada, Diego
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    Toward a Neutral Single-Component Amidinate Iodide Aluminum Catalyst for the CO2 Fixation into Cyclic Carbonates
    (2021) Saltarini, Sebastián; Villegas, Nery Andrés; Martínez, Javier; Daniliuc, Constantin G.; Matute, Ricardo A.; Gade, Lutz H.; Rojas Guerrero, René
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    Toward a Neutral Single-Component Amidinate Iodide Aluminum Catalyst for the CO2 Fixation into Cyclic Carbonates
    (2021) Saltarini, Sebastian; Villegas-Escobar, Nery; Martinez, Javier; Daniliuc, Constantin G.; Matute, Ricardo A.; Gade, Lutz H.; Rojas, Rene S.
    A new iodide aluminum complex ({AlI(kappa(4)-naphbam)}, 3) supported by a tetradentate amidinate ligand derived from a naphthalene-1,8-bisamidine precursor (naphbamH, 1) was obtained in quantitative yield via reaction of the corresponding methyl aluminum complex ({AlMe(kappa(4)-naphbam)}, 2) with 1 equiv of I-2 in CH2Cl2 at room temperature. Complexes 2 and 3 were tested and found to be active as catalysts for the cyclic carbonate formation from epoxides at 80 degrees C and 1 bar of CO2 pressure. A first series of experiments were carried out with 1.5 mol % of the alkyl complex 2 and 1.5 mol % of tetrabutylammonium iodide (TBAI) as a cocatalyst; subsequently, the reactions were carried out with 1.5 mol % of iodide complex 3 as a single-component catalyst. Compound 3 is one of the first examples of a nonzwitterionic halide single-component aluminum catalyst producing cyclic carbonates. The full catalytic cycle with characterization of all minima and transition states was characterized by quantum chemistry calculations (QCCs) using density functional theory. QCCs on the reaction mechanism support a reaction pathway based on the exchange of the iodine contained in the catalyst by 1 equiv of epoxide, with subsequent attack of I- to the epoxide moiety producing the ring opening of the epoxide. QCCs triggered new insights for the design of more active halide catalysts in future explorations of the field.