Confinement Effects for Efficient Macrocyclization Reactions with Supported Cationic Molybdenum Imido Alkylidene <i>N</i>-Heterocyclic Carbene Complexes

Ziegler, Felix; Kraus, Hamzeh; Benedikter, Mathis; Wang, Dongren; Bruckner, Johanna R.; Nowakowski, Michał; Weißer, Kilian; Solodenko, Helena; Schmitz, Guido; Hansen, Niels; Buchmeiser, Michael R.

doi:10.1021/acscatal.1c03057

Cited by 23 publications

(57 citation statements)

References 51 publications

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“…However, intrinsically stable N -heterocyclic carbenes (NHC) are widely used in heterogeneous catalysis as surface ligands. , [For those interested in applications of NHC as surface ligands in catalysis, we recommend refs , .] The NHC anchored-supported surfaces-particles vary from elemental metal allotrope species to bulk crystals, and also their applications vary from photo/electrocatalysis to thermalcatalysis. − In the early 2010s, Sanchez and his co-workers reported the immobilization of pincer-type NHC-metal (i.e., Ru, Rh, and Au) complexes in ordered mesoporous silica structures (MCM-41). , They studied the stability and structure of immobilized metal–carbene complexes via a battery of spectroscopic methods ( 13 C CP solid-state NMR, FTIR, UV–vis DRS) and tested the catalysts for hydrogenation of olefins and dehydrogenation of alcohols. In comparison to homogeneous catalysts, promising performance and recycling ability were observed with the hybrid mesoporous materials.…”

Section: Carbene Chemistry In Zeolite Catalysismentioning

confidence: 99%

First-Generation Organic Reaction Intermediates in Zeolite Chemistry and Catalysis

Gong

Çağlayan

et al. 2022

Chem. Rev.

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Zeolite chemistry and catalysis are expected to play a decisive role in the next decade(s) to build a more decentralized renewable feedstock-dependent sustainable society owing to the increased scrutiny over carbon emissions. Therefore, the lack of fundamental and mechanistic understanding of these processes is a critical “technical bottleneck” that must be eliminated to maximize economic value and minimize waste. We have identified, considering this objective, that the chemistry related to the first-generation reaction intermediates (i.e., carbocations, radicals, carbenes, ketenes, and carbanions) in zeolite chemistry and catalysis is highly underdeveloped or undervalued compared to other catalysis streams (e.g., homogeneous catalysis). This limitation can often be attributed to the technological restrictions to detect such “short-lived and highly reactive” intermediates at the interface (gas–solid/solid–liquid); however, the recent rise of sophisticated spectroscopic/analytical techniques (including under in situ/operando conditions) and modern data analysis methods collectively compete to unravel the impact of these organic intermediates. This comprehensive review summarizes the state-of-the-art first-generation organic reaction intermediates in zeolite chemistry and catalysis and evaluates their existing challenges and future prospects, to contribute significantly to the “circular carbon economy” initiatives.

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Section: Carbene Chemistry In Zeolite Catalysismentioning

confidence: 99%

First-Generation Organic Reaction Intermediates in Zeolite Chemistry and Catalysis

Gong

Çağlayan

et al. 2022

Chem. Rev.

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“…The simulation suite GROMACS 2016.5 [46,47] was used for all simulations, while PLUMED 2.5 [48,49] was utilized to extract specific distances and angles. Based on earlier work [50,51], the general Amber force field (GAFF) [52] was chosen to describe intra-and intermolecular interactions. This is further backed up by the quality of the GAFF-compatible force field q4md-CD for cyclodextrin simulations [40,53].…”

Section: Simulation Parametersmentioning

confidence: 99%

An atomistic view on the uptake of aromatic compounds by cyclodextrin immobilized on mesoporous silica

Kraus

Hansen

2022

Adsorption

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The effect of immobilized $$\upbeta$$ β -cyclodextrin (bCD) molecules inside a mesoporous silica support on the uptake of benzene and p-nitrophenol from aqueous solution was investigated using all-atom molecular dynamics (MD) simulations. The calculated adsorption isotherms are discussed with respect to the free energies of binding for a 1:1 complex of bCD and the aromatic guest molecule. The adsorption capacity of the bCD-containing material significantly exceeds the amount corresponding to a 1:1 binding scenario, in agreement with experimental observations. Beside the formation of 1:2 and, to a lesser extent, 1:3 host:guest complexes, also host–host interactions on the surface as well as more unspecific host–guest interactions govern the adsorption process. The demonstrated feasibility of classical all-atom MD simulations to calculate liquid phase adsorption isotherms paves the way to a molecular interpretation of experimental data that are too complex to be described by empirical models.

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“…For instance, interactions of functionalized olefins containing ester groups and surface silanol groups were recently found to enrich the near-surface concentration of olefins and influence product selectivities for ring-closing metathesis reactions catalyzed by well-defined cationic Mo alkylidenes supported on mesoporous silicas. 54 The silica-supported Mo oxo system is known to possess strong Brønsted acid sites that could act as adsorption sites, 11,55 and even on bare hydroxylated silica the interaction energies of hydrocarbons are known to increase as a function of chain length and are greater for alkenes than alkanes. 56 The catalytic reaction tests and spectroscopic analyses discussed above show that substratesilica interactions are non-negligible for long-chain olefinic hydrocarbons and indeed have significant effects on catalytic reaction properties at low reaction temperatures (<100 °C).…”

Section: Dynamics and Adsorption Of Olefins On Silicamentioning

confidence: 99%

Olefin-surface interactions: a key activity parameter in silica-supported olefin metathesis catalysts

Berkson

Bernhardt

Schlapansky

et al. 2022

Preprint

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Molecularly defined and classical heterogenous Mo-based metathesis catalysts are shown to display dis-tinct and unexpected reactivity patterns for the metathesis of long-chain α-olefins at low temperatures (< 100 °C). Namely, catalysts based on supported Mo oxo species, whether prepared via wet impregnation or surface organometallic chemistry (SOMC), exhibit strong activity dependencies on the α-olefin chain length, with slower reaction rates for longer substrate chain lengths. In contrast, molecular and support-ed Mo alkylidenes are highly active and do not display such dramatic dependence on chain length. State-of-the-art 2D solid-state NMR analyses of post-metathesis catalysts, complemented by FTIR and molecular dynamics calculations, evidence that the activity decrease observed for supported Mo oxo catalysts relates to the strong adsorption of internal olefin metathesis products due to interactions with surface Si-OH groups. Overall, this study shows that in addition to the nature and the number of active sites, the metathesis rates and overall catalytic performance depend on product desorption, even in the liquid phase with non-polar substrates. This study further highlights the role of support and active site composition and dynamics on activity as well as the need to consider adsorption in catalyst design.

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Confinement Effects for Efficient Macrocyclization Reactions with Supported Cationic Molybdenum Imido Alkylidene N-Heterocyclic Carbene Complexes

Cited by 23 publications

References 51 publications

First-Generation Organic Reaction Intermediates in Zeolite Chemistry and Catalysis

First-Generation Organic Reaction Intermediates in Zeolite Chemistry and Catalysis

An atomistic view on the uptake of aromatic compounds by cyclodextrin immobilized on mesoporous silica

Olefin-surface interactions: a key activity parameter in silica-supported olefin metathesis catalysts

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