Òscar González-Blanco

Autonomous University of Barcelona, Cerdanyola del Vallès, Catalonia, Spain

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Publications (7)17.1 Total impact

  • Carles Acosta-Silva, Oscar Gonzalez-Blanco, Vicenç Branchadell
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    ABSTRACT: The hetero-Diels-Alder reactions of butadiene with Fe(CO)(3)-coordinated formylbutadiene and formyltrimethylenemethane catalyzed by Lewis acids have been theoretically studied through density functional calculations. The results obtained show that, for the reaction with (formylbutadiene)Fe(CO)(3), the kinetically most favourable product is the one corresponding to the attack of butadiene on the s-cis conformer of the formylbutadiene fragment when the reaction is catalyzed by BF(3), and the one corresponding to the attack on the s-trans conformer when the catalyst is TiCl(4). On the other hand, for the reaction with (formyltrimethylenemethane)Fe(CO)(3) catalyzed by BF(3), the product corresponding to the attack on the s-trans conformer is predicted to be favoured. These results have been interpreted through an energy decomposition analysis of the potential-energy barriers.
    Canadian Journal of Chemistry 01/2009; 87:1074. · 0.96 Impact Factor
  • Òscar González-Blanco, Vicenç Branchadell
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    ABSTRACT: The 1,3-metal shift process has been studied for several conjugated cyclic and acyclic (η4-triene)Fe(CO)3 systems. In all cases the transition state of the process corresponds to (η2-triene)Fe(CO)3 structures. The computed energy barriers are notably higher for acyclic complexes than for the cyclic ones, in good agreement with the experimental observations. The analysis of the energy barriers shows that this is due to the different orientations of the triene ligand in the transition states, which leads to more efficient stabilizing metal−ligand orbital interactions for the cyclic systems.
    Organometallics. 09/2000; 19(22).
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    ABSTRACT: The structures of several complexes arising from the interaction between methylene and palladium and rhodium diformates were optimized through density functional calculations. For palladium, mono-, di-, and trimeric complexes were considered. The results obtained show that in all cases the most stable structures correspond to complexes in which methylene has inserted in one of the M–O bonds, while metal–carbene complexes are energy minima only for monomeric palladium diformate and for rhodium diformate. Trimeric palladium formate is thermodynamically stable upon fragmentation. However, when it reacts with methylene, fragmentation becomes favorable. The role of the resulting monomeric complex in the olefin cyclopropanation mechanism catalyzed by palladium dicarboxylates is discussed.
    Berichte der deutschen chemischen Gesellschaft 01/2000; 2000(5):1073-1078. · 2.94 Impact Factor
  • Òscar González-Blanco, Vicenç Branchadell, René Grée
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    ABSTRACT: A very good correlation was observed between the relative energies of the stable conformers in substituted derivatives of [(η4-butadiene)Fe(CO)3], obtained from density functional calculations performed on the conformational equilibria that correspond to C−C rotations (see diagram), and the experimentally observed diastereomeric ratios in several kinds of reactions.
    Chemistry 05/1999; 5(6):1722 - 1727. · 5.93 Impact Factor
  • Oscar González-Blanco, Vicenç Branchadell
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    ABSTRACT: Fe(CO)n (n=1–5) complexes have been studied using density functional theory (DFT) methods. Several functionals have been used in the geometry optimizations, harmonic frequencies computation and calculation of the iron–carbonyl bond dissociation energies. Coupled-cluster single double (triple) bond dissociation energies have also been computed for the smaller systems. The obtained results show that DFT methods yield reasonable geometries and vibrational frequencies. Regarding the bond dissociation energies, it is shown that the validity of the results depends on whether there is a change in the atomic state of the metal during the dissociation. When the atomic state is the same for both complexes, the bond dissociation energy computed using gradient corrected functionals is within the range of the experimental values, while when the atomic state changes, DFT methods overestimate the bond dissociation energy due to a poor description of the atomic multiplets. © 1999 American Institute of Physics.
    The Journal of Chemical Physics 01/1999; 110(2):778-783. · 3.12 Impact Factor
  • Òscar González-Blanco, Vicenç Branchadell, Kereen Monteyne, Tom Ziegler
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    ABSTRACT: Density functional theory calculations have been carried out on the trigonal complexes OsO3E and MCl3E (M = V, Ta) and the square pyramidal systems MCl4E (M = Cr, Mo, W, Re) for E = O, S, Se, and Te as well as (C5H5)ReO3. All complexes were fully optimized, and the calculated geometrical parameters are in reasonable agreement with gas-phase electron diffraction data where available. The calculated M−E bond energies decrease from oxygen to tellurium, from bottom to top in a metal triad, and from left to right in a transition series. The trend setting factor is the donation from the dσ metal orbital to the pσ acceptor orbital on the chalcogen atom. The contribution from the chalcogen to metal π back-donation has a maximum for sulfur and selenium. However in relative terms, the contribution from the π back-donation to the total M−E bond energy increases from oxygen to tellurium. Comparisons are made to previous calculations and experimental data on M−E bond strengths.
    03/1998;
  • Òscar González-Blanco, Vicenç Branchadell
    Organometallics 01/1997; 16(3):475-481. · 4.15 Impact Factor