8 research outputs found
Etude théorique des réactions d'oligomérisation des oléfines catalysées par des complexes du fer
Les catalyseurs bis(imino)pyridine au fer sont hautement actifs en oligo/polymérisation des oléfines. L'IFP souhaite les étudier pour transformer l'éthylène, extrait du bioéthanol, en oléfines linéaires (de C16 à C24) qui alimenteraient le pool diesel.Cependant, leur activation génère une espèce de nature inconnue. Nos calculs DFT montrent que l'état d'oxydation +III (spin quadruplet) est l'état actif le plus favorable.En outre, la combinaison d'un modèle cinétique et des calculs DFT décrit précisément les résultats expérimentaux d'oligomérisation du butène-1 et donne un support additionnel à la pertinence de l'espèce activée retenue.Par ailleurs, cette espèce a permis d'établir une relation linéaire entre le coefficient Schulz-Flory, informant du degré d'oligomérisation expérimental, et la différence des enthalpies libres d'activation de réactions d'insertion et de terminaison particulières. Cette relation a aussi permis de rationaliser le comportement de ces catalyseurs vis-à -vis des changements de substituants. Enfin, son potentiel universel est avancé par l'extension de son domaine d'application à d'autres catalyseurs.PARIS-BIUSJ-Physique recherche (751052113) / SudocSudocFranceF
Theoretical Unraveling of Selective 1-Butene Oligomerization Catalyzed by Iron−Bis(arylimino)pyridine
Characterizing Agosticity Using the Quantum Theory of Atoms in Molecules: Bond Critical Points and Their Local Properties
In this paper, we extend the work of Popelier and Logothetis
[J. Organomet. Chem. 1998, 555, 101]
on the characterization of agosticity by considerably enlarging the
set of the studied organometallic molecules. To this aim, 23 representative
complexes have been considered, including all first line transition
metals at various oxidation states and exhibiting four types of agosticity
(α, β, γ, and δ). From these examples, the
concepts of agostic atom, agostic bond, and agostic interaction are
defined and discussed, notably by advocating Bader’s analysis
of the electron density. The nature and the local properties of the
bond critical points are then investigated, and the relationships
with the main geometric parameters of the complexes are particularly
examined. Moreover, new local descriptors based on kinetic energy
densities are developed in order to provide new tools for bond characterization
Synthesis of new RuO2@SiO2 composite nanomaterials and their application as catalytic filters for selective gas detection
RuO2@SiO2 nanomaterials are prepared using hybrid mesostructured silica (EtO)2P(O)(CH2)3SiO1.5/x SiO2 (x = 9, 16) by anchoring the metal precursor [Ru(COD)(COT)] (COD is 1,3-cyclooctadiene, COT is 1,3,5-cyclooctatriene) inside the pores of the organized silica matrix through the phosphonate moieties. Following this task, the nanoparticles are fabricated by i) decomposing the metal precursor with hydrogen at room temperature in tetrahydrofuran to achieve ruthenium nanoparticles and ii) thermally treating the ruthenium particles in silica at 450 °C in air to fabricate RuO2. The materials containing Ru and RuO2 nanoparticles are characterized by elemental analysis, transmission electron microscopy (TEM), X-ray diffraction (XRD), nitrogen sorption measurements, and 31P and 13C NMR. The obtained RuO2@SiO2 nanomaterials are evaluated as catalytic filters when deposited onto gas sensors for the preferential detection of propane in the multicomponent gas mixture propane/carbon monoxide/nitrogen dioxide