N-Heterocyclic Carbene (NHC) Ligands - Sigma-Aldrich.
N-Heterocyclic Carbenes in Catalytic Organic Synthesis. These volumes provide a user’s guide to NHC chemistry and catalysis, thus facilitating the introduction of NHCs to novices and also helping to expand the repertoire of synthetic tools available to the more-advanced researcher, enabling the design of new catalysts and reactions.
A range of iridium(I) complexes of the type (Ir(cod)(NHC)PPh 3))X are reported, where the N-heterocyclic carbene (NHC) is derived from the naturally-occurring imidaozlium salt, Lepidiline A (1,3-dibenzyl-4,5-dimethylimidazolium chloride). A range of complexes were prepared, with a number of NHC ligands and counter-ions, and various steric and electronic parameters of these complexes were.
Scheme 1.2 Synthesis of an NHC-mercury complex (5). 2 1 N-Heterocyclic Carbenes (Figure 1.2) (7). Notably, these were far less sterically hindered, suggesting that the origin of their stability was electronic, rather than steric, or was a combina-tion of these factors. The aromatic nature of the imidazolium ring was thought to be critical to the stability of NHCs. However, in 1995, NHC 7.
This thesis concerns the synthesis, structural characterisation and reactivity of a range of novel organometallic complexes. The research primarily focuses on N-heterocyclic carbenes as ligands, and their coordination to copper cations. A novel electrochemical synthetic procedure for the synthesis of CuI-NHC complexes is described. It was found that this procedure was suitable for the.
The tetramethyl carbene complex 3 exhibits a similar chemical shift in toluene, but shows a higher frequency signal in acetonitrile arising from the solvent adduct (Ru(IMe4)4(MeCN)H) (BArF4), 4. The reactivity of 1-3 towards H2 and N2 depends on the size of the N-substituent of the NHC ligand. Thus, 1 is unreactive towards both gases, 2 reacts.
Synthesis of free carbenes. Interactions between the nitrogen substituents and the metal center prevent normal NHC complexes from forming. If the carbene is part of a bidentate ligand with a forced geometry, the MIC complex may form preferentially as well. The counteranion of imidazolium salts participates in NHC vs. MIC formation. NHC formation typically occurs by heterolytic bond cleavage.
The optimized strategy to heterobimetallic complexes with this type of ligand involves a 3-step procedure: (i) Coordination of the nNHC, functionalized with a 1,2,3-triazole ring, to a metal center; (ii) formation of the triazolium ring by alkylation of the triazole N-3; (iii) deprotonation of the tzNHC precursor and coordination of the second metal center. Following this procedure, a novel Au.