H/D Exchange on Silica-Grafted Tantalum(V) Imido Amido [(≡SiO)2Ta(V)(NH)(NH2)] Synthesized from Either Ammonia or Dinitrogen: IR and DFT Evidence for Heterolytic Splitting of D2
| Autor: | Laurent Veyre, Odile Eisenstein, Elsje Alessandra Quadrelli, Priscilla Avenier, Xavier Solans-Monfort, Jean-Marie Basset, Filippo Renili, Mostafa Taoufik |
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| Přispěvatelé: | Laboratoire de Chimie, Catalyse, Polymères et Procédés, R 5265 (C2P2), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-École supérieure de Chimie Physique Electronique de Lyon (CPE)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), IFP Energies nouvelles (IFPEN), departament de Quimica, Universitat Autònoma de Barcelona (UAB), Dipartimento di Chimica e Chimica Industriale, University of Pisa - Università di Pisa, Institut Charles Gerhardt Montpellier - Institut de Chimie Moléculaire et des Matériaux de Montpellier (ICGM ICMMM), Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Université Montpellier 1 (UM1)-Université Montpellier 2 - Sciences et Techniques (UM2)-Institut de Chimie du CNRS (INC) |
| Rok vydání: | 2009 |
| Předmět: |
Hydrogen
010405 organic chemistry Chemistry Stereochemistry chemistry.chemical_element Infrared spectroscopy General Chemistry 010402 general chemistry 01 natural sciences Heterolysis Catalysis 0104 chemical sciences Crystallography Deuterium Isotopic shift Yield (chemistry) Density functional theory [PHYS.PHYS.PHYS-CHEM-PH]Physics [physics]/Physics [physics]/Chemical Physics [physics.chem-ph] ComputingMilieux_MISCELLANEOUS |
| Zdroj: | Topics in Catalysis Topics in Catalysis, Springer Verlag, 2009, 52, pp.1482-1491. ⟨10.1007/s11244-009-9295-0⟩ |
| ISSN: | 1572-9028 1022-5528 |
| DOI: | 10.1007/s11244-009-9295-0 |
| Popis: | The silica-grafted Ta(V) imido amido complex [(≡SiO)2Ta(NH)(NH2)], 2, obtained from the reaction of either ammonia or dinitrogen plus hydrogen with the silica-grafted hydrides [(≡SiO)2Ta(III)H], 1a, and [(≡SiO)2Ta(V)H3], 1b, undergoes H/D exchange with D2. In situ IR spectroscopy shows that the fully labelled compound [(≡SiO)2Ta(ND)(ND2)], 2-d, can be obtained by moderate heating (60 °C, 3 h) under D2 atmosphere (550 torr, 300 eq. with respect to Ta), and that the exchange is reversible. The observed stretching and bending frequencies of 2-d are in agreement with the expected isotopic shift upon H/D replacement with respect to literature values reported for 2 and have been corroborated by the independent synthesis of 2-d by reaction of deuterated 1a and 1b with N2 and D2. Density functional theory (DFT) calculations, performed using a periodic or a cluster model, explored the structures and energetics of all minima involved in the reaction with H2 and showed that among the explored pathways the energetically preferred mechanisms for H2 reaction with [{(μ-O)[(HO)2SiO]2}Ta(V)(NH)(NH2)], 2q, is the heterolytic cleavage of either the imido Ta=N or the amido Ta-N bonds, to yield respectively [{(μ-O)[(HO)2SiO]2}TaH(NH2)2], 3q (ΔE = −9.5 kcal mol−1 and ΔG298K = +2.6 kcal mol−1 with respect to 2q) and [{(μ-O)[(HO)2SiO]2}Ta(NH)(NH3)], 4q (ΔE = −6.0 kcal mol−1 and ΔG298K = +7.9 kcal mol−1 with respect to 2q). All activation barriers are moderate (between 17.7 and 30.2 kcal mol−1) in agreement with the observed mild heating conditions necessary for the reaction to occur. |
| Databáze: | OpenAIRE |
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