Homogenous carbene

Anchoring of Pd via a carbene linkage to a polymer resin substantially increased Pd TON (up to 5100) compared with homogeneous carbene systems (80-150) [38]. 

The pre.sent account follows a Journey in this arena from solution calorimetric studies dealing with nucleophilic carbene ligands in an organometallic system to the use of these thermodynamic data in predicting the feasibility of exchange reactions to applications in homogeneous catalysis. 

APPLICATIONS OF NUCLEOPHILIC CARBENES AS CATALYST PRECURSORS IN HOMOGENEOUS CATALYSIS... 

Abstract The use of A-heterocyclic carbene (NHC) complexes as homogeneous catalysts in addition reactions across carbon-carbon double and triple bonds and carbon-heteroatom double bonds is described. The discussion is focused on the description of the catalytic systems, their current mechanistic understanding and occasionally the relevant organometallic chemistry. The reaction types covered include hydrogenation, transfer hydrogenation, hydrosilylation, hydroboration and diboration, hydroamination, hydrothiolation, hydration, hydroarylation, allylic substitution, addition, chloroesterification and chloroacylation. 

Table 3.15. Fischer-type carbene complexes as catalysts for homogeneous-phase alkene metathesis.

Peris E (2006) Routes to N-Heterocydic Carbene Complexes. 21 83-116 Fitter S, Dinjus E, lonescu C, Maniut C, Makarczyk P, Patcas F (2008) Evaluation of Supercritical Carbon Dioxide as a Tuneable Reaction Medium for Homogeneous Catalysis. 23 109-147... 

Homogeneous Catalysis through Heterogeneous Ru Carbenes 471 Tab. 11.1 Ring-closing metathesis of acyclic dienes by Ru complex (10). ... 

Iridium N-Heterocyclic Carbene Complexes and Their Application as Homogeneous Catalysts... 

Sola, M. Duran, M. Torrent, M. The Dotz reaction A chromium Eischer carbene-mediated benzannulation reaction. In Computational Modeling of Homogeneous Catalysis Maseras, E. Lledos, A. eds. Kluwer Academic Boston 2002, 269—287. (Review). 

Metal complexes of stable carbenes—or more precisely metal complexes of car-benes that are now known to be stable—have developed from laboratory curiosities to widely used compounds. The basis for this development was laid by Wanzlick s and Ofele s discoveries in the 1960s, the recent revival has certainly been driven by Arduengo s first isolation of an A-heterocyclic carbene in 1991, and the result is a permanently increasing number of synthetic routes towards precursors for stable carbenes, towards stable carbenes themselves, and their metal complexes. Simultaneously with their accessibility, the applicability of these compounds to various fields such as homogeneous catalysis, materials science, medicinal and bioinorganic chemistry has been evaluated. 

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