Nickel N-Heterocyclic Carbene-Catalyzed C–C Bond Formation: Reactions and Mechanistic Aspects

Abstract

The chemistry of nickel N-heterocyclic carbene complexes is a research area that has blossomed over the last 10 years, and a large number of new complexes with a variety of architectural motifs are now known. The evolution of this chemistry has led to increasing applications of these complexes in catalytic bond formation. The rapid expansion of this field now calls for a review of the kinds of reactions that are catalyzed and a summary of the state of the art at this time. As the breadth of reactions catalyzed by such complexes is vast, this review specifically targets catalytic C–C bond formation, in particular C–C cross-couplings and C–C couplings via C–H bond activation, mediated by nickel–N-heterocyclic carbene complexes. A special emphasis is placed on mechanistic data, because this allows possible new insights into catalyst improvement.

Nickel(II) N‐Heterocyclic Carbene Complexes: Versatile Catalysts for C–C, C–S and C–N Coupling Reactions

“…Traditionally, this reaction has been carried out by using aryl halides as electrophiles, aryl boronic acids as nucleophiles and Pd‐based catalysts . Some nickel complexes have shown activity towards this transformation, including recently described nickel complexes bearing monodentate NHC ligands . Aiming for the generation of new and versatile catalysts, complexes 2a – f and 3a , c and g were synthesised and tested in Suzuki–Miyaura reactions.…”

“…The use of η 5 ‐C 5 H 5 (Cp) or η 5 ‐C 5 Me 5 (Cp*) ligands will lead to more electron‐rich catalytic precursors, which may be more stable as a result of the steric bulkiness of both ligands as described for many coupling reactions . A review comprising the recent advances in the use of Ni–NHC complexes in C–C coupling reactions was published recently . However, few examples of Ni–NHC complexes bearing Cp and Cp* have been reported.…”

Substituent effect and ligand exchange control the reactivity in ruthenium(II)-catalyzed hydroacylation of isoprenes and aldehydes ‖ A DFT study

“…Several results could be summarized as follows: (1) These reactions began from the¯rst catalytic cycle (path I), and the nucleophilic reaction was predicted to be the rate-determining step. (2) The di®erence between path I and path II was the hydrogen migration. (3) Because the activation barriers of hydrogen migration were the highest in two catalytic cycles, the hydrogen migration was the rate-determining step.…”

“…[1][2][3][4][5][6][7][8][9][10][11] Hydroacylation is one of the most useful C-H bond activation processes, [7][8][9][10][11] and represents an ordinary, green, atom-e±cient synthetic approach. 12 Enormous e®orts have been devoted to develop more convenient and e±cient strategies for catalytic hydroacylation.…”

Pd(II)–N-heterocyclic carbene complexes of annelated ligand: Synthesis, characterization, and catalytic activity

“…Owing to the electronic tunability, modification and ease of synthesis for a wide range of metal ions, the NHCs have been incorporated in a large variety of catalytically active metal complexes [24,25]. Development of new novel class of NHC ligands [26][27][28][29][30] by donor-functionalization, including weak-donor functionalized NHCs (wdf-NHC) have also played an important role in organometallic chemistry and catalysis [31,32]. The C, N-donor NHC ligands can provide considerable benefits due to the extra stability they impart to intermediates in a catalytic reaction [14][15][16].…”