Please use this identifier to cite or link to this item: http://repositorio.ufla.br/jspui/handle/1/31598
Title: Methane C–H bond activation by niobium oxides: theoretical analyses of the bonding and reactivity properties of Nbomn+(m = 1, 2; n = 0, 1, 2)
Keywords: Methane - Catalytic properties
Electrostatic interaction
Niobium oxides
Metano - Propriedades catalíticas
Interação eletrostática
Óxidos de nióbio
Issue Date: 15-Jan-2016
Publisher: Elsevier
Citation: ALMEIDA, K. J. de et al. Methane C–H bond activation by niobium oxides: theoretical analyses of the bonding and reactivity properties of Nbomn+(m = 1, 2; n = 0, 1, 2). Journal of Organometallic Chemistry, Lausanne, v. 802, p. 49-59, 15 Jan. 2016.
Abstract: The catalytic properties of NbOnþ m (m ¼ 1, 2; n ¼ 0, 1, 2) on the methane CeH bond activation were investigated using B3LYP and CCSD(T) calculations. The spineorbit relativistic effects were evaluated by means of ZORA approximations. The main results indicate that in agreement with the previous experimental findings only the neutral NbO monoxide is kinetically and thermodynamically feasible via the oxidative addition, whereas the remaining oxides and dioxides show better theoretical predictions in the hydrogen abstraction pathways. In these reactions, a known mechanism described as “Oxidative Hydrogen Migration (OHM)” was found to be more stable for the neutral and singly charged niobium-oxo species, while competitive direct H abstraction (DHA) and OHM pathways were obtained for the doubly charged niobium oxides, with slightly preferential conditions observed in DHA. Overall, the increase of charge on the metal center and the presence of the oxo ligands favors the initial electrostatic interaction between niobium oxides and methane, decreasing the activation barrier heights in the H abstraction pathways due to the electron acceptor nature of oxo ligands. Among the investigated oxides, NbO2þ and NbO2þ 2 show the best performances in the methane activation process, with activation barriers computed to be around 1.5e5.9 kcal mol1.
URI: https://www.sciencedirect.com/science/article/pii/S0022328X15302102#!
http://repositorio.ufla.br/jspui/handle/1/31598
Appears in Collections:DQI - Artigos publicados em periódicos

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