Advertisement

Topics

C-H bond activation of benzene by unsaturated η2-cyclopropene and η2-benzyne complexes of niobium.

06:00 EDT 23rd September 2010 | BioPortfolio

Summary of "C-H bond activation of benzene by unsaturated η2-cyclopropene and η2-benzyne complexes of niobium."

We report the synthesis of a niobium cyclopropyl complex, Tp(Me2)NbMe(c-C(3)H(5))(MeCCMe), and show that thermal loss of methane from this compound generates an intermediate that is capable of activating both aliphatic and aromatic C-H bonds. Isotopic labeling, trapping studies, a detailed kinetic analysis, and density functional theory all suggest that the active intermediate is an η(2)-cyclopropene complex formed via β-hydrogen abstraction rather than an isomeric cyclopropylidene species. C-H activation chemistry of this type represents a rather unusual reactivity pattern for η(2)-alkene complexes but is favored in this case by the strain in the C(3) ring which prevents the decomposition of the key intermediate via loss of cyclopropene.

Affiliation

CNRS, Laboratoire de Chimie de Coordination, 205 Route de Narbonne, F-31077 Toulouse, France.

Journal Details

This article was published in the following journal.

Name: Journal of the American Chemical Society
ISSN: 1520-5126
Pages: 14239-50

Links

DeepDyve research library

PubMed Articles [8282 Associated PubMed Articles listed on BioPortfolio]

Rhodium-Catalyzed C-H Bond Functionalization with Amides by Double C-H/C-N Bond Activation.

The first C-H bond functionalization with amides as the coupling partners via selective activation of the amide N-C bond using rhodium(I) catalysts under highly chemoselective conditions is reported. ...

Predicting Promoter-Induced Bond Activation on Solid Catalysts Using Elementary Bond Orders.

In this Letter, we examine bond activation induced by nonmetal surface promoters in the context of dehydrogenation reactions. We use C-H bond activation in methane dehydrogenation on transition metals...

Frontispiece: General Route to Cyclobutadiene Rhodium Complexes.

Sandwich Complexes The center of the stained glass represents the top view of the cyclobutadiene rhodium benzene complex [(C4 H4 )Rh(C6 H6 )](+) . This sandwich compound not only shows the geometric b...

Bottom-Up Construction of a CO2-Based Cycle for the Photocarbonylation of Benzene Promoted by a Rhodium(I) Pincer Complex.

The use of CO2 for synthetic applications presents a major goal in modern homogenous catalysis. Rhodium-hydride PNP pincer complex 1 is shown to add CO2 in two disparate pathways. One is the expected ...

Revisiting the glass transition and dynamics of supercooled benzene by calorimetric studies.

The glass transition and dynamics of benzene are studied in binary mixtures of benzene with five glass forming liquids, which can be divided into three groups: (a) o-terphenyl and m-xylene, (b) N-buty...

Clinical Trials [751 Associated Clinical Trials listed on BioPortfolio]

Modulation of Benzene Metabolism by Exposure to Environment

The research is to evaluate benzene metabolism after exposure at levels that can be found in the environment, such as the higher end concentrations in the air inside cars and buses while b...

Molecular Epidemiology of Benzene-Exposed Workers.

The purpose of this study is to investigate the health effects of benzene exposure in workers in Shanghai, China.

Biomarkers of Benzene Exposure in Inner City Residents

This study compares air pollution exposures of residents in a South Baltimore community next to major industry with those in a comparison community with much less industry nearby. Parents ...

Benzene Exposure as a Risk Factor for Hematological Cancer or Related Disorders or Lung Cancer in Chinese Workers

RATIONALE: Exposure to low-level benzene in the work place may affect the risk of developing cancer later in life. Learning about the long-term effects of benzene exposure may help the stu...

Validation of Brief Objective Neurobehavioral Detectors (BOND) in Mild TBI

The Veterans Health Administration (VHA) has stated the need for a brief screening instrument that can assist with the triage of the enormous number of returning OEF/OIF veterans with conc...

Medical and Biotech [MESH] Definitions

Niobium. A metal element atomic number 41, atomic weight 92.906, symbol Nb. (From Dorland, 28th ed)

Complexes of enzymes that catalyze the covalent attachment of UBIQUITIN to other proteins by forming a peptide bond between the C-terminal GLYCINE of UBIQUITIN and the alpha-amino groups of LYSINE residues in the protein. The complexes play an important role in mediating the selective-degradation of short-lived and abnormal proteins. The complex of enzymes can be broken down into three components that involve activation of ubiquitin (UBIQUITIN-ACTIVATING ENZYMES), conjugation of ubiquitin to the ligase complex (UBIQUITIN-CONJUGATING ENZYMES), and ligation of ubiquitin to the substrate protein (UBIQUITIN-PROTEIN LIGASES).

The sequential activation of serum COMPLEMENT PROTEINS to create the COMPLEMENT MEMBRANE ATTACK COMPLEX. Factors initiating complement activation include ANTIGEN-ANTIBODY COMPLEXES, microbial ANTIGENS, or cell surface POLYSACCHARIDES.

UNSATURATED FATTY ACIDS that contain at least one double bond in the trans configuration, which results in a greater bond angle than the cis configuration. This results in a more extended fatty acid chain similar to SATURATED FATTY ACIDS, with closer packing and reduced fluidity. HYDROGENATION of unsaturated fatty acids increases the trans content.

Unsaturated derivatives of the steroid androstane containing at least one double bond at any site in any of the rings.

Quick Search
Advertisement
 


DeepDyve research library

Searches Linking to this Article