Metal Carbenes in Organic Synthesis

Metal Carbenes in Organic Synthesis PDF Author: K H Dtz
Publisher: Springer Science & Business Media
ISBN: 9783540218333
Category : Science
Languages : en
Pages : 396

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With contributions by numerous experts

Metal Carbenes in Organic Synthesis

Metal Carbenes in Organic Synthesis PDF Author: K H Dtz
Publisher: Springer Science & Business Media
ISBN: 9783540218333
Category : Science
Languages : en
Pages : 396

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Book Description
With contributions by numerous experts

Fischer Chromium Carbenes in Organic Synthesis

Fischer Chromium Carbenes in Organic Synthesis PDF Author: Ellen Elizabeth Burns
Publisher:
ISBN:
Category :
Languages : en
Pages : 682

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Metal Carbenes in Organic Synthesis

Metal Carbenes in Organic Synthesis PDF Author: Florencio Zaragoza Dörwald
Publisher: John Wiley & Sons
ISBN: 3527614079
Category : Science
Languages : en
Pages : 290

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There are hardly more versatile compounds in organic synthesis than carbene complexes. The rapid development of new synthetic methods involving carbene complexes - stereoselective cyclopropanation, carbonyl olefination, olefin metathesis, etc. - reveals the value and high potential of these compounds. Their application ranges from the synthesis of fine chemicals to polymer production. This comprehensive, well structured handbook presents the fundamental principles and the recent advances in carbene complex chemistry. Arranged according to structure and reactivity, all relevant classes of carbene complexes, their generation, and application in organic synthesis are discussed in detail. Critically selected, up-to-date references and valuable experimental procedures await the reader. Every chemist searching for a concise introduction and reference work for carbene complex chemistry will welcome this practical guide. "...this concise presentation of all the aspects of the use of carbene complexes in synthesis will help provide the impetus for even more rapid developments in this field of research." R. H. Grubbs (Caltech)

Fischer Carbene Complexes

Fischer Carbene Complexes PDF Author: Ying You
Publisher:
ISBN:
Category :
Languages : en
Pages : 850

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Chromium and Iron Organometallics in Organic Synthesis

Chromium and Iron Organometallics in Organic Synthesis PDF Author: Yiqian Lian
Publisher:
ISBN:
Category : Carbenes (Methylene compounds)
Languages : en
Pages : 604

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Chromium Carbene Complexes in Organic Synthesis

Chromium Carbene Complexes in Organic Synthesis PDF Author: James Edward Painter
Publisher:
ISBN:
Category :
Languages : en
Pages : 136

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Advances in Metal Carbene Chemistry

Advances in Metal Carbene Chemistry PDF Author: U. Schubert
Publisher: Springer Science & Business Media
ISBN: 9400923171
Category : Science
Languages : en
Pages : 405

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There are only few topics in organometallic chemistry, which have stimulated research activities in as many areas, as transition-metal carbene (alkylidene) complexes. About 25 years after the first planned synthesis of a carbene complex in E.O. Fischer's laboratory in Munich the NATO Advanced Research Workshop on Transition-Metal Carbene Complexes was the first meeting which,brought together scientists from different disciplines to discuss inorganic, organic, theoretical structural catalysis-related aspects of metal carbene chemistry. The 70th birthday of Professor E.O. Fischer was a good occasion for this enterprise. The organizers of the meeting (K.D. Dotz, Marburg; F.R. KreiBl, Munchen; U. Schubert, Wurzburg) were encouraged by the fact that most of the leading scientists in this area were able to participate in the workshop. The very high standard of the contributions is reflected in this book, which contains papers from the majority of the participants. The Proceedings show the state of the art in metal carbene chemistry and will hopefully be a landmark in the development of this area of chemistry. Generous financial support for the workshop and for the preparation of this book was provided by the Scientific Affairs Division of NATO and some companies. The organizers also acknowledge the efforts of the staff of the Bildungs zentrum der Hans-Seidel-Stiftung in Wild bad Kreuth for creating a pleasant and stimulating atmosphere during the conference.

Beta -substituted Chromium Carbene Complexes in Organic Synthesis

Beta -substituted Chromium Carbene Complexes in Organic Synthesis PDF Author: James Edward Painter
Publisher:
ISBN:
Category :
Languages : en
Pages : 165

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Fischer and N-heterocyclic Carbene Complexes of Chromium(0)

Fischer and N-heterocyclic Carbene Complexes of Chromium(0) PDF Author: Roan Fraser
Publisher:
ISBN:
Category : Carbenes (Methylene compounds)
Languages : en
Pages : 368

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The central focus of this study was the synthesis, structural investigation and characterisation of multiple chromium carbene complexes. Fifteen novel chromium(0) complexes were synthesised. The synthesis of the primary monocarbene starting material [Cr(CO)5{C(OEt)(heteroaryl)}], heteroaryl = thiophene, furan, 2,2’-bithiophene, was carried out utilising typical Fischer methodology. A wide variation of spacer ligands were reacted to obtain different carbene substituents. The ligand substitution reaction between carbonyl ligands and the bidentate ligands followed the techniques proposed in literature and produced distinctive chelated monocarbene complexes with the resulting structure mer- [Cr(CO)3(dppe){carbene)}]. An extensive collection of more sophisticated monocarbene complexes was synthesised via modification pathways (aminolysis). Conversion of original ethoxy-bearing monocarbenes through aminolysis provided the corresponding amine analogues, possessing both novel structure and unique chemical reactivity. The aminolysis reactions involved different sized amino reagents; both ammonia and cyclohexyl amine (bulky, cyclic chair amines) were employed to produce derivatives of the monocarbene starting complexes. Lastly, the synthesis of unique N-heterocyclic carbene (NHC) complexes was envisaged. Synthesis of both the pentacarbonyl-bearing and phosphine-bearing NHC complexes was attempted utilising an adapted version of a methodology proposed in literature. The synthesis of chelate NHC complexes, however, proved difficult and the resulting products were not obtained. All Fischer and N-heterocyclic carbene complexes were characterised using infrared spectroscopy, nuclear magnetic resonance spectroscopy and mass spectrometry. In cases where single crystals were obtained, X-ray crystallography was used to confirm molecular structures. X-ray crystallographic studies indicated that carbonyl substitution reactions performed on monocarbene starting material, will favour the formation of the meridonial isomer in molecules where the carbene substituents are less bulky. Due to steric considerations, the substitution of labile carbonyl ligands in the trans position to the carbene moiety will be favoured. Density functional theory (DFT) calculations were performed on the complexes synthesised in this study. The results obtained indicated the favoured isomeric form to be facial in some cases whereas crystallographic data signified the meridonial isomer as the more stable product, irrespective of the bulkiness of the carbene substituents. Bond lengths, geometry and bond angles were all comparable to those of the single-crystal X-ray data. Single-point energy calculations show clearly that modelling methods provide good estimations of energetically favourable geometries, and accurate DFT calculations also predict the HOMO and LUMO orientations around the metal or ligand spheres. The majority of the structures provided by the computed model, illustrated that the 3d atomic orbitals of the metal contributed significantly to the HOMO, whereas the LUMO was mostly orientated around the carbene carbon atom. Metathesis and polymerisation catalytic reactions were attempted on [Cr(CO)3(dppe){C(OEt)(thiophene)}], 2, whereas only metathesis studies were employed for [Cr(CO)3(dppe){C(NHCy)(thiophene)}], 6. Both complexes presented as inert to either reaction and no catalytic capability was witnessed. Gas chromatography was used to indicate the level of progression of the reaction and the chromatogram verified that neither pre-catalyst found application in metathesis or, in the case of 2, in polymerisation.

Chromium Carbenes in Organic Synthesis

Chromium Carbenes in Organic Synthesis PDF Author: Michael Raymond Hallett
Publisher:
ISBN:
Category :
Languages : en
Pages : 174

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