Carbon-hydrogen bond activation by a titanium neopentylidene complex
Нема приказа
Аутори
Ninković, DraganMoncho, Salvador
Petrović, Predrag
Zarić, Snežana D.
Hall, Michael B.
Brothers, Edward N.
Чланак у часопису (Објављена верзија)
Метаподаци
Приказ свих података о документуАпстракт
The titanium neopentylidene complex (PNP)Ti=(CHBu)-Bu-t((CH2Bu)-Bu-t), PNP=N[2-(PPr2)-Pr-i-4-methylphenyl](2)(-), can activate both sp(2) and sp(3) C-H bonds under mild conditions. In this work, we studied the reaction mechanism of this complex with benzene and methane using modern density functional theory, specifically the B97XD functional which contains long-range exchange and dispersion corrections. The mechanism of the reaction is similar to that computed previously in the literature, but we describe a new conformer that is both more stable and kinetically more reactive. The four-step mechanism is very similar for both benzene and methane. However, the highest energy barriers differ; for methane, it is the last step, which elucidates the inertness of that reactant. In addition, the hydrogen exchange between alkyl and alkylidene ligands in methane's product was studied by two different mechanisms: tautomerization to form (PNP)(TiCHBu)-Bu-t(=CH2) and reverse C-H activation to form (...PNP)(TiCBu)-Bu-t(CH3). The feasibility of the tautomerization, through a preliminary, accessible isomerization, suggests that these systems can be used to explore the reactivity of terminal methylidenes. Finally, methodological considerations are also discussed, as the importance of including the dispersion in the density functionals was determined by comparing several functionals. This comparison has shown that the dispersion is critical for accurate modeling, especially in the stability of the unsaturated intermediate; this has been neglected in previous studies. [GRAPHICS] .
Кључне речи:
C-H bond activation / DFT / reaction mechanisms / transition metal complexesИзвор:
Journal of Coordination Chemistry, 2016, 69, 11-13, 1759-1768Издавач:
- Taylor & Francis Ltd, Abingdon
Финансирање / пројекти:
- NPRP grant from Qatar National Research Fund (Qatar Foundation) [7-297-1-051]
DOI: 10.1080/00958972.2016.1172701
ISSN: 0095-8972
WoS: 000380129800008
Scopus: 2-s2.0-84966592174
Институција/група
Hemijski fakultet / Faculty of ChemistryTY - JOUR AU - Ninković, Dragan AU - Moncho, Salvador AU - Petrović, Predrag AU - Zarić, Snežana D. AU - Hall, Michael B. AU - Brothers, Edward N. PY - 2016 UR - https://cherry.chem.bg.ac.rs/handle/123456789/2281 AB - The titanium neopentylidene complex (PNP)Ti=(CHBu)-Bu-t((CH2Bu)-Bu-t), PNP=N[2-(PPr2)-Pr-i-4-methylphenyl](2)(-), can activate both sp(2) and sp(3) C-H bonds under mild conditions. In this work, we studied the reaction mechanism of this complex with benzene and methane using modern density functional theory, specifically the B97XD functional which contains long-range exchange and dispersion corrections. The mechanism of the reaction is similar to that computed previously in the literature, but we describe a new conformer that is both more stable and kinetically more reactive. The four-step mechanism is very similar for both benzene and methane. However, the highest energy barriers differ; for methane, it is the last step, which elucidates the inertness of that reactant. In addition, the hydrogen exchange between alkyl and alkylidene ligands in methane's product was studied by two different mechanisms: tautomerization to form (PNP)(TiCHBu)-Bu-t(=CH2) and reverse C-H activation to form (PNP)(TiCBu)-Bu-t(CH3). The feasibility of the tautomerization, through a preliminary, accessible isomerization, suggests that these systems can be used to explore the reactivity of terminal methylidenes. Finally, methodological considerations are also discussed, as the importance of including the dispersion in the density functionals was determined by comparing several functionals. This comparison has shown that the dispersion is critical for accurate modeling, especially in the stability of the unsaturated intermediate; this has been neglected in previous studies. [GRAPHICS] . PB - Taylor & Francis Ltd, Abingdon T2 - Journal of Coordination Chemistry T1 - Carbon-hydrogen bond activation by a titanium neopentylidene complex VL - 69 IS - 11-13 SP - 1759 EP - 1768 DO - 10.1080/00958972.2016.1172701 ER -
@article{ author = "Ninković, Dragan and Moncho, Salvador and Petrović, Predrag and Zarić, Snežana D. and Hall, Michael B. and Brothers, Edward N.", year = "2016", abstract = "The titanium neopentylidene complex (PNP)Ti=(CHBu)-Bu-t((CH2Bu)-Bu-t), PNP=N[2-(PPr2)-Pr-i-4-methylphenyl](2)(-), can activate both sp(2) and sp(3) C-H bonds under mild conditions. In this work, we studied the reaction mechanism of this complex with benzene and methane using modern density functional theory, specifically the B97XD functional which contains long-range exchange and dispersion corrections. The mechanism of the reaction is similar to that computed previously in the literature, but we describe a new conformer that is both more stable and kinetically more reactive. The four-step mechanism is very similar for both benzene and methane. However, the highest energy barriers differ; for methane, it is the last step, which elucidates the inertness of that reactant. In addition, the hydrogen exchange between alkyl and alkylidene ligands in methane's product was studied by two different mechanisms: tautomerization to form (PNP)(TiCHBu)-Bu-t(=CH2) and reverse C-H activation to form (PNP)(TiCBu)-Bu-t(CH3). The feasibility of the tautomerization, through a preliminary, accessible isomerization, suggests that these systems can be used to explore the reactivity of terminal methylidenes. Finally, methodological considerations are also discussed, as the importance of including the dispersion in the density functionals was determined by comparing several functionals. This comparison has shown that the dispersion is critical for accurate modeling, especially in the stability of the unsaturated intermediate; this has been neglected in previous studies. [GRAPHICS] .", publisher = "Taylor & Francis Ltd, Abingdon", journal = "Journal of Coordination Chemistry", title = "Carbon-hydrogen bond activation by a titanium neopentylidene complex", volume = "69", number = "11-13", pages = "1759-1768", doi = "10.1080/00958972.2016.1172701" }
Ninković, D., Moncho, S., Petrović, P., Zarić, S. D., Hall, M. B.,& Brothers, E. N.. (2016). Carbon-hydrogen bond activation by a titanium neopentylidene complex. in Journal of Coordination Chemistry Taylor & Francis Ltd, Abingdon., 69(11-13), 1759-1768. https://doi.org/10.1080/00958972.2016.1172701
Ninković D, Moncho S, Petrović P, Zarić SD, Hall MB, Brothers EN. Carbon-hydrogen bond activation by a titanium neopentylidene complex. in Journal of Coordination Chemistry. 2016;69(11-13):1759-1768. doi:10.1080/00958972.2016.1172701 .
Ninković, Dragan, Moncho, Salvador, Petrović, Predrag, Zarić, Snežana D., Hall, Michael B., Brothers, Edward N., "Carbon-hydrogen bond activation by a titanium neopentylidene complex" in Journal of Coordination Chemistry, 69, no. 11-13 (2016):1759-1768, https://doi.org/10.1080/00958972.2016.1172701 . .