4.6 Article

Macrocyclization of Dienes under Confinement with Cationic Tungsten Imido/Oxo Alkylidene N-Heterocyclic Carbene Complexes

Related references

Note: Only part of the references are listed.
Article Polymer Science

Tungsten Oxo and Tungsten Imido Alkylidene N-Heterocyclic Carbene Complexes for the Visible-Light-Induced Ring-Opening Metathesis Polymerization of Dicyclopentadiene

Janis V. Musso et al.

Summary: A system for visible-light-controlled ring-opening metathesis polymerization (ROMP) was developed by combining thermally latent group 6 olefin metathesis initiators with a photoredox catalyst. This system can be applied to two-dimensional (2D) photolithography, and it exhibits high activity and stability without the need for thermal or UV post-curing.

MACROMOLECULES (2023)

Article Chemistry, Physical

Olefin Metathesis under Spatial Confinement and Continuous Flow: Investigation of Isomeric Side Reactions with a Grubbs-Hoveyda Type Catalyst

Andre Both et al.

Summary: In this study, a 2(nd)-generation Grubbs-Hoveyda type catalyst was immobilized in mesoporous silica and used in the ring-closing metathesis (RCM) of an alpha,omega-diene to a large macro(mono)cycle. The relationship between substrate concentration, reaction time, and overall experiment time on the rate of isomerization under spatial confinement with continuous-flow microreactors was investigated. The results showed that higher substrate concentrations and longer reaction times increased the isomerization rate, while prolonged overall experiment times led to a decline in the isomerization rate.

CHEMCATCHEM (2023)

Article Chemistry, Multidisciplinary

Olefin Metathesis in Confinement: Towards Covalent Organic Framework Scaffolds for Increased Macrocyclization Selectivity

Sebastian T. Emmerling et al.

Summary: Covalent organic frameworks (COFs) offer vast structural and chemical diversity, and have the potential to play a greater role in catalytic reactions. This study demonstrates the alteration of reactions under spatial confinement by immobilizing specific catalysts on COF pore walls. The results show significantly improved selectivity in macrocyclization reactions compared to homogeneous catalysts, along with a substrate-size dependency in selectivity.

CHEMISTRY-A EUROPEAN JOURNAL (2022)

Article Chemistry, Physical

Cationic Molybdenum Imido Alkylidene N-Heterocyclic Carbene Complexes Confined in Mesoporous Silica: Tuning Transition States Towards Z-Selective Ring-Opening Cross-Metathesis

Elizabeth L. Goldstein et al.

Summary: This article reports a method for selective macro(mono)cyclization of dienes using catalysts confined inside mesoporous silica and finds that the proximity of the catalyst to the surface of silica material affects the selectivity. The catalyst displays a higher Z-selectivity when confined inside a pore or bound to non-porous silica.

CHEMCATCHEM (2022)

Article Chemistry, Physical

Olefin Ring-closing Metathesis under Spatial Confinement: Morphology-transport Relationships

Ulrich Tallarek et al.

Summary: The study quantified the effects of spatial confinement on hindered transport in mesoporous silica particles using reconstructions of their morphology as geometrical models in diffusion simulations, examining the interactions between tracers and pore space confinement based on the tracer to mean mesopore size ratio. The hindrance factors derived for different ratios quantify the hindrance of diffusion through the materials compared to free diffusion, providing insights into morphology-transport relationships and the immobilization, formation, and transport of key molecular species in ring-closing metathesis.

CHEMCATCHEM (2021)

Article Chemistry, Multidisciplinary

Rh(I)/(III)-N-Heterocyclic Carbene Complexes: Effect of Steric Confinement Upon Immobilization on Regio- and Stereoselectivity in the Hydrosilylation of Alkynes

Pradeep K. R. Panyam et al.

Summary: Rh(I) NHC and Rh(III) Cp* NHC complexes were immobilized inside mesoporous SBA-15, showing different reactivity and selectivity, particularly for aliphatic alkynes. The immobilized catalysts in SBA-15 exhibited excellent selectivity in hydrosilylation reactions, attributed to the confinement effect generated during immobilization.

CHEMISTRY-A EUROPEAN JOURNAL (2021)

Article Chemistry, Physical

Olefin Ring-closing Metathesis under Spatial Confinement and Continuous Flow

Felix Ziegler et al.

Summary: The study demonstrates the efficient use of a 2(nd)-generation Hoveyda-Grubbs-type catalyst immobilized inside mesoporous silica for selective macro(mono)cyclization (MMC) of an alpha,omega-diene under spatially confined and continuous-flow conditions. By analyzing reaction mixtures through NMR and MALDI-TOF-MS, the study identifies the effects of confinement on olefin metathesis pathways and determines conditions for achieving high MMC selectivity. The research also highlights the preference for ring-closing metathesis of monomers and backbiting from dimers and trimers under confinement, leading to a high MMC selectivity of 60%.

CHEMCATCHEM (2021)

Article Chemistry, Physical

Mechanisms and Intermediates in the True Liquid Crystal Templating Synthesis of Mesoporous Silica Materials

Johanna R. Bruckner et al.

Summary: The study uses small-angle X-ray scattering to monitor the structural evolution during templating process of mesoporous silica materials (MSMs) produced by true liquid crystal templating (TLCT). It reveals the formation of an intermediary liquid crystal phase as a key step to the success of templating process, connecting the structural parameters of the initial LLC and the MSM via a simple theoretical model. These findings contribute to a better understanding of the TLCT process and pave the way for predictable synthesis of new MSMs in the future.

JOURNAL OF PHYSICAL CHEMISTRY B (2021)

Article Chemistry, Inorganic & Nuclear

Cationic Tungsten Imido Alkylidene N-Heterocyclic Carbene Complexes That Contain Bulky Ligands

Roman Schowner et al.

Summary: The synthesis of tungsten imido alkylidene complexes with neutral and cationic properties was achieved, leading to successful homometathesis of unfunctionalized olefins. The reactivity of these complexes in various reactions was investigated, resulting in the first fully characterized cationic tungsten(IV) NHC ethylene complex.

ORGANOMETALLICS (2021)

Article Chemistry, Physical

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

Felix Ziegler et al.

Summary: By utilizing cationic molybdenum imido alkylidene N-heterocyclic carbene (NHC) complexes confined in tailored ordered mesoporous silica, high macrocyclization selectivities up to 98% and high substrate concentrations up to 0.1 M can be achieved. Molecular dynamics simulations reveal that high conversions are a result of the proximity between the surface-bound catalyst and surface-located substrates, leading to increased reaction efficiency.

ACS CATALYSIS (2021)

Article Polymer Science

Cationic tungsten imido alkylidene N-heterocyclic carbene complexes for stereospecific ring-opening metathesis polymerization of norbornene derivatives

Janis V. Musso et al.

Summary: The stereospecific ring-opening metathesis polymerization (ROMP) of DMMNBE was successfully achieved using cationic tungsten imido alkylidene N-heterocyclic carbene (NHC) complexes as initiators, showing high trans-isospecifity of up to 95%. Tuning the steric demand of the ligands of the metal complexes allowed for a change in stereoselectivity in the reaction.

POLYMER CHEMISTRY (2021)

Article Chemistry, Inorganic & Nuclear

Cationic Tungsten AlkylidyneN-Heterocyclic Carbene Complexes: Synthesis and Reactivity in Alkyne Metathesis

Philipp M. Hauser et al.

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY (2020)

Review Chemistry, Inorganic & Nuclear

Group 6 metal alkylidene and alkylidyne N-heterocyclic carbene complexes for olefin and alkyne metathesis

Mathis J. Benedikter et al.

COORDINATION CHEMISTRY REVIEWS (2020)

Article Chemistry, Multidisciplinary

Olefin Metathesis in Confined Geometries: A Biomimetic Approach toward Selective Macrocyclization

Felix Ziegler et al.

JOURNAL OF THE AMERICAN CHEMICAL SOCIETY (2019)

Proceedings Paper Instruments & Instrumentation

A beamline for bulk sample X-ray absorption spectroscopy at the high brilliance storage ring PETRA III

Edmund Welter et al.

13TH INTERNATIONAL CONFERENCE ON SYNCHROTRON RADIATION INSTRUMENTATION (SRI2018) (2019)

Article Chemistry, Multidisciplinary

Molybdenum Imido, Tungsten Imido and Tungsten Oxo Alkylidene N-Heterocyclic Carbene Olefin Metathesis Catalysts

Michael R. Buchmeiser

CHEMISTRY-A EUROPEAN JOURNAL (2018)

Article Chemistry, Physical

Diffusion of Water and Electrolytes in Mesoporous Silica with a Wide Range of Pore Sizes

Diana C. Martinez Casillas et al.

JOURNAL OF PHYSICAL CHEMISTRY C (2018)

Article Chemistry, Multidisciplinary

Iminium Catalysis inside a Self-Assembled Supramolecular Capsule: Scope and Mechanistic Studies

Thomas M. Brauer et al.

JOURNAL OF THE AMERICAN CHEMICAL SOCIETY (2017)

Article Chemistry, Multidisciplinary

Structure and reactivity of a mononuclear gold(II) complex

Sebastian Preiss et al.

NATURE CHEMISTRY (2017)

Article Chemistry, Physical

Consistent structures and interactions by density functional theory with small atomic orbital basis sets

Stefan Grimme et al.

JOURNAL OF CHEMICAL PHYSICS (2015)

Article Chemistry, Multidisciplinary

Cationic Tungsten-Oxo-Alkylidene-N-Heterocyclic Carbene Complexes: Highly Active Olefin Metathesis Catalysts

Roman Schowner et al.

JOURNAL OF THE AMERICAN CHEMICAL SOCIETY (2015)

Article Chemistry, Multidisciplinary

Nucleophilic Substitution Catalyzed by a Supramolecular Cavity Proceeds with Retention of Absolute Stereochemistry

Chen Zhao et al.

JOURNAL OF THE AMERICAN CHEMICAL SOCIETY (2014)

Article Chemistry, Organic

Highly Selective Macrocycle Formations by Metathesis Catalysts Fixated in Nanopores

Joo-Eun Jee et al.

JOURNAL OF ORGANIC CHEMISTRY (2013)

Article Chemistry, Multidisciplinary

Stereoselective Access to Z and E Macrocycles by Ruthenium-Catalyzed Z-Selective Ring-Closing Metathesis and Ethenolysis

Vanessa M. Marx et al.

JOURNAL OF THE AMERICAN CHEMICAL SOCIETY (2013)

Article Chemistry, Multidisciplinary

The ORCA program system

Frank Neese

WILEY INTERDISCIPLINARY REVIEWS-COMPUTATIONAL MOLECULAR SCIENCE (2012)

Article Instruments & Instrumentation

ATHENA, ARTEMIS, HEPHAESTUS:: data analysis for X-ray absorption spectroscopy using IFEFFIT

B Ravel et al.

JOURNAL OF SYNCHROTRON RADIATION (2005)

Article Chemistry, Multidisciplinary

Structure and diffusion characterization of SBA-15 materials

VT Hoang et al.

LANGMUIR (2005)