Heterolytic cleavage of ammonia N-H bond by bifunctional activation in silica-grafted single site Ta(V) imido amido surface complex. Importance of the outer sphere NH3 assistance

Handle URI:
http://hdl.handle.net/10754/561647
Title:
Heterolytic cleavage of ammonia N-H bond by bifunctional activation in silica-grafted single site Ta(V) imido amido surface complex. Importance of the outer sphere NH3 assistance
Authors:
Gouré, Eric; Avenier, Priscilla; Soláns, Xavier Luis; Veyre, Laurent; Baudouin, Anne Christine; Kaya, Yasemin; Taoufik, Mostafa; Basset, Jean-Marie ( 0000-0003-3166-8882 ) ; Eisenstein, Odile; Quadrelli, Elsje Alessandra
Abstract:
Ammonia N-H bond is cleaved at room temperature by the silica-supported tantalum imido amido complex [(≡SiO)2Ta(NH)(-NH2)], 2, if excess ammonia is present, but requires 150 °C to achieve the same reaction if only one equivalent NH3 is added to 2. MAS solid-state 15N NMR and in situ IR spectroscopic studies of the reaction of either 15N or 2H labeled ammonia with 2 show that initial coordination of the ammonia is followed by scrambling of either 15N or 2H among ammonia, amido and imido groups. Density functional theory (DFT) calculations with a cluster model [{(μ-O)[(H3SiO) 2SiO]2}Ta(NH)(-NH2)(NH3)], 2 q·NH3, show that the intramolecular H transfer from Ta-NH2 to TaNH is ruled out, but the H transfers from the coordinated ammonia to the amido and imido groups have accessible energy barriers. The energy barrier for the ammonia N-H activation by the Ta-amido group is energetically preferred relative to the Ta-imido group. The importance of excess NH3 for getting full isotope scrambling is rationalized by an outer sphere assistance of ammonia acting as proton transfer agent, which equalizes the energy barriers for H transfer from coordinated ammonia to the amido and imido groups. In contrast, additional coordinated ammonia does not favor significantly the H transfer. These results rationalize the experimental conditions used. © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2011.
KAUST Department:
KAUST Catalysis Center (KCC); Physical Sciences and Engineering (PSE) Division; Chemical Science Program
Publisher:
Royal Society of Chemistry
Journal:
New Journal of Chemistry
Issue Date:
2011
DOI:
10.1039/c1nj20032a
Type:
Article
ISSN:
11440546
Appears in Collections:
Articles; Physical Sciences and Engineering (PSE) Division; Chemical Science Program; KAUST Catalysis Center (KCC)

Full metadata record

DC FieldValue Language
dc.contributor.authorGouré, Ericen
dc.contributor.authorAvenier, Priscillaen
dc.contributor.authorSoláns, Xavier Luisen
dc.contributor.authorVeyre, Laurenten
dc.contributor.authorBaudouin, Anne Christineen
dc.contributor.authorKaya, Yaseminen
dc.contributor.authorTaoufik, Mostafaen
dc.contributor.authorBasset, Jean-Marieen
dc.contributor.authorEisenstein, Odileen
dc.contributor.authorQuadrelli, Elsje Alessandraen
dc.date.accessioned2015-08-03T09:01:19Zen
dc.date.available2015-08-03T09:01:19Zen
dc.date.issued2011en
dc.identifier.issn11440546en
dc.identifier.doi10.1039/c1nj20032aen
dc.identifier.urihttp://hdl.handle.net/10754/561647en
dc.description.abstractAmmonia N-H bond is cleaved at room temperature by the silica-supported tantalum imido amido complex [(≡SiO)2Ta(NH)(-NH2)], 2, if excess ammonia is present, but requires 150 °C to achieve the same reaction if only one equivalent NH3 is added to 2. MAS solid-state 15N NMR and in situ IR spectroscopic studies of the reaction of either 15N or 2H labeled ammonia with 2 show that initial coordination of the ammonia is followed by scrambling of either 15N or 2H among ammonia, amido and imido groups. Density functional theory (DFT) calculations with a cluster model [{(μ-O)[(H3SiO) 2SiO]2}Ta(NH)(-NH2)(NH3)], 2 q·NH3, show that the intramolecular H transfer from Ta-NH2 to TaNH is ruled out, but the H transfers from the coordinated ammonia to the amido and imido groups have accessible energy barriers. The energy barrier for the ammonia N-H activation by the Ta-amido group is energetically preferred relative to the Ta-imido group. The importance of excess NH3 for getting full isotope scrambling is rationalized by an outer sphere assistance of ammonia acting as proton transfer agent, which equalizes the energy barriers for H transfer from coordinated ammonia to the amido and imido groups. In contrast, additional coordinated ammonia does not favor significantly the H transfer. These results rationalize the experimental conditions used. © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2011.en
dc.publisherRoyal Society of Chemistryen
dc.titleHeterolytic cleavage of ammonia N-H bond by bifunctional activation in silica-grafted single site Ta(V) imido amido surface complex. Importance of the outer sphere NH3 assistanceen
dc.typeArticleen
dc.contributor.departmentKAUST Catalysis Center (KCC)en
dc.contributor.departmentPhysical Sciences and Engineering (PSE) Divisionen
dc.contributor.departmentChemical Science Programen
dc.identifier.journalNew Journal of Chemistryen
dc.contributor.institutionUniversité de Lyon, UMR 5265 C2P2, (UCBL Lyon 1- CPE Lyon -CNRS), École Supérieure Chimie Physique Electronique, 43 Boulevard du 11 Novembre 1918, Villeurbanne, Franceen
dc.contributor.institutionDepartament de Quimica, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spainen
dc.contributor.institutionInstitut Charles Gerhardt, Université Montpellier 2, CNRS 5253, cc 1501 Place E. Bataillon, 34095 Montpellier, Franceen
dc.contributor.institutionGorlaeus Laboratories, Universiteit Leiden, Leiden Institute of Chemistry, Einsteinweg 55, 2333 CC Leiden, Netherlandsen
dc.contributor.institutionIFP-Lyon, Rond-Point de LEchangeur de Solaize, BP3, 69360, Franceen
kaust.authorBasset, Jean-Marieen
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