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Titolo:
Activity of peroxo and hydroperoxo complexes of Ti-IV in olefin epoxidation: A density functional model study of energetics and mechanism
Autore:
Yudanov, IV; Gisdakis, P; Di Valentin, C; Rosch, N;
Indirizzi:
Univ Munich, Inst Phys & Theoret Chem, D-85747 Munich, Germany Univ Munich Munich Germany D-85747 Theoret Chem, D-85747 Munich, Germany Russian Acad Sci, Boreskov Inst Catalysis, Siberian Branch, Novosibirsk 630090, Russia Russian Acad Sci Novosibirsk Russia 630090 h, Novosibirsk 630090, Russia Univ Pavia, Dipartimento Chim Organ, I-27100 Pavia, Italy Univ Pavia Pavia Italy I-27100 rtimento Chim Organ, I-27100 Pavia, Italy
Titolo Testata:
EUROPEAN JOURNAL OF INORGANIC CHEMISTRY
fascicolo: 12, , anno: 1999,
pagine: 2135 - 2145
SICI:
1434-1948(199912):12<2135:AOPAHC>2.0.ZU;2-A
Fonte:
ISI
Lingua:
ENG
Soggetto:
METAL-CATALYZED EPOXIDATIONS; HYDROGEN-PEROXIDE; TITANIUM-SILICALITE; CRYSTAL-STRUCTURE; ASYMMETRIC EPOXIDATION; BASIS-SETS; MOLYBDENUM; OXO;
Keywords:
density functional calculations; epoxidation; peroxo complexes; titanium; transition states;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
46
Recensione:
Indirizzi per estratti:
Indirizzo: Rosch, N Univ Munich, Inst Phys & Theoret Chem, D-85747 Munich, Germany Univ Munich Munich Germany D-85747 hem, D-85747 Munich, Germany
Citazione:
I.V. Yudanov et al., "Activity of peroxo and hydroperoxo complexes of Ti-IV in olefin epoxidation: A density functional model study of energetics and mechanism", EUR J INORG, (12), 1999, pp. 2135-2145

Abstract

Epoxidation of olefins by Ti-IV peroxo and hydroperoxo (alkylperoxo) complexes was investigated using a hybrid DFT method (B3LYP). Reaction energies and activation barriers for direct oxygen transfer to ethylene as a model olefin were computed for various model complexes to compare the epoxidation activity of Ti(eta(2)-O-2) and TiOOR (R = H, CH3) moieties. The activity ofcomplexes with a Ti(O-2) peroxo group is shown to be essentially quenched when the coordination sphere of the complex is saturated by strongly basic (sigma-donor) ligands. In contrast, the activity of a TiOOH functional group depends only weakly on the saturation of the coordination sphere of the Ti center. Substitution of methyl for hydrogen in a TiOOH group is found to slightly increase the activation barrier of epoxidation. The computational results give preference to reaction paths that involve TiOOR species. The factors governing the activity of Ti(O-2) and TiOOR groups, in particular the effects of donor Ligands, are discussed on the basis of a molecular orbital analysis.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 18/09/20 alle ore 17:17:27