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Carbene Complexes

A special issue of Molecules (ISSN 1420-3049).

Deadline for manuscript submissions: closed (31 December 2011) | Viewed by 16123

Special Issue Editor

Department of Chemistry, National University of Singapore, Singapore, Singapore
Interests: N-heterocyclic carbenes; homogeneous catalysis; organometallic chemistry

Special Issue Information

Dear Colleagues,

N-heterocyclic carbenes (NHCs) have become state-of-the-art ligands in organometallic chemistry due to their strong donating ability. Their properties can be easily influenced through modification of the backbone and substituents leading to stable complexes with a wide range of metal centres, which have found applications in diverse areas such as catalysis, materials, bioorganometallic and supramolecular chemistry. Current developments also include the synthesis of new stable NHCs or other related strong donor ligands, e.g. mesoionic carbenes, and their complexes. With this special issue on carbene complexes we are aiming to highlight the current diversity in this research area.

Dr. Han Vinh Huyah
Guest Editor

Keywords

  • carbene complexes
  • N-heterocyclic carbenes
  • donor-functionalization
  • mesoionic/abnormal carbenes
  • catalysis
  • materials
  • bioorganometallic
  • supramolecular chemistry

Published Papers (2 papers)

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Research

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345 KiB  
Article
Understanding the Mechanism of the Intramolecular Stetter Reaction. A DFT Study
by Luis R. Domingo, Ramón J. Zaragozá, Jose A. Saéz and Manuel Arnó
Molecules 2012, 17(2), 1335-1353; https://doi.org/10.3390/molecules17021335 - 02 Feb 2012
Cited by 35 | Viewed by 7568
Abstract
The mechanism of the N-heterocyclic carbene (NHC)-catalyzed intramolecular Stetter reaction of salicylaldehyde 1 to yield chromanone 3 has been theoretically studied at the B3LYP/6-31G** level. This NHC-catalyzed reaction takes place through six elementary steps, which involve: (i) formation of the Breslow intermediate [...] Read more.
The mechanism of the N-heterocyclic carbene (NHC)-catalyzed intramolecular Stetter reaction of salicylaldehyde 1 to yield chromanone 3 has been theoretically studied at the B3LYP/6-31G** level. This NHC-catalyzed reaction takes place through six elementary steps, which involve: (i) formation of the Breslow intermediate IN2; (ii) an intramolecular Michael-Type addition in IN2 to form the new C-C s bond; and (iii) extrusion of the NHC catalyst from the Michael adduct to yield chromanone 3. Analysis of the relative free energies in toluene indicates that while formation of Breslow intermediate IN2 involves the rate-determining step of the catalytic process, the intramolecular Michael-type addition is the stereoselectivity determining step responsible for the configuration of the stereogenic carbon a to the carbonyl of chromanone 3. An ELF analysis at TSs and intermediates involved in the Michael-type addition allows for the characterization of the electronic changes along the C-C bond-formation. Full article
(This article belongs to the Special Issue Carbene Complexes)
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Review

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2263 KiB  
Review
Sulfur-Functionalized N-Heterocyclic Carbene Complexes of Pd(II): Syntheses, Structures and Catalytic Activities
by Dan Yuan and Han Vinh Huynh
Molecules 2012, 17(3), 2491-2517; https://doi.org/10.3390/molecules17032491 - 01 Mar 2012
Cited by 86 | Viewed by 8160
Abstract
N-heterocyclic carbenes (NHCs) can be easily modified by introducing functional groups at the nitrogen atoms, which leads to versatile coordination chemistry as well as diverse catalytic applications of the resulting complexes. This article summarizes our contributions to the field of NHCs bearing different [...] Read more.
N-heterocyclic carbenes (NHCs) can be easily modified by introducing functional groups at the nitrogen atoms, which leads to versatile coordination chemistry as well as diverse catalytic applications of the resulting complexes. This article summarizes our contributions to the field of NHCs bearing different types of sulfur functions, i.e., thioether, sulfoxide, thiophene, and thiolato. The experimental evidence for the truly hemilabile coordination behavior of a Pd(II) thioether-NHC complex has been reported as well. In addition, complexes bearing rigid CSC-pincer ligands have been synthesized and the reasons for pincer versus pseudo-pincer formation investigated. Incorporation of the electron-rich thiolato function resulted in the isolation of structurally diverse complexes. The catalytic activities of selected complexes have been tested in Suzuki-Miyaura, Mizoroki-Heck and hydroamination reactions. Full article
(This article belongs to the Special Issue Carbene Complexes)
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