N-Heterocyclic Carbene Complexes of Copper, Nickel, and Cobalt

Abstract

The emergence of N-heterocyclic carbenes as ligands across the Periodic Table had an impact on various aspects of the coordination, organometallic, and catalytic chemistry of the 3d metals, including Cu, Ni, and Co, both from the fundamental viewpoint but also in applications, including catalysis, photophysics, bioorganometallic chemistry, materials, etc. In this review, the emergence, development, and state of the art in these three areas are described in detail.

An Efficient A3 Coupling Catalyst Based on a Silver Complex Bearing N‐Heterocyclic Carbene and Homoscorpionate Bis(3‐methyl‐mercaptoimidazolyl)borate Ligands

“…For example, some of these reactions require high reaction temperatures or a high percentage of catalyst loading is required to achieve higher yields of products . Among carbene ligands, N‐heterocyclic carbenes, commonly known as NHCs, are excellent sigma donor ligands and their electronic and steric properties are adjustable by changing the nature of substituents on the nitrogen atoms . While different salts or nanostructures of coinage metals have been utilized as catalysts for A 3 coupling reactions, reports in regards to the N‐heterocyclic complexes of these metals are rare.…”

“…[32] Among carbene ligands, Nheterocyclic carbenes, commonly known as NHCs, are excellent sigma donor ligands and their electronic and steric properties are adjustable by changing the nature of substituents on the nitrogen atoms. [47][48][49][50][51][52][53][54][55][56][57][58][59][60] While different salts or nanostructures of coinage metals have been utilized as catalysts for A 3 coupling reactions, reports in regards to the N-heterocyclic complexes of these metals are rare. Recently, Zhang et al have utilized fiber supported N-heterocyclic carbene Ag(I) as catalyst for three component coupling reactions.…”

Imidazole‐Bridged Tetrameric Group(IV) Heteroleptic Complexes from the Spontaneous Metal‐Ligand Assembly of a Potentially N4‐Tetradentate Ligand

“…The reaction was initially accomplished in a J-Young NMR tube as to follow its course spectroscopically. 1 H NMR spectra of both solutions revealed that reactions proceeded smoothly in [D 6 ]benzene already at room temperature to give solutions containing unique coordination compounds [L2 Bn Zr(NMe 2 ) 3 (6) and L2 Bn Hf(NMe 2 ) 3 (7, Figure 2), respectively], as tris(dimethylamido) forms. With both metal precursors, the ligand complexation was extremely clean and complete within 30 min.…”

“…[1] In particular, the preparation of multidentate N-ligands (N > 2) and the study of their metal ion coordination behavior is a welldeveloped research area in contemporary organometallic chemistry. [2][3][4][5][6][7][8][9][10][11][12][13] The introduction of aromatic N-containing heterocycles like pyridine, [14] triazole, [15] or pyrazole [16,17] has contributed to expand the variety of N-multidentate backbones. Their hapticity varies as a function of the degree of the ligand's skeleton flexibility.…”

Magnetically Recoverable Catalysts: Catalysis in Synthesis of Polyhydroquinolines

“…Although most of the reported procedures offer obvious advantages, they suffer from some drawbacks i.e. the use of high temperatures, expensive metal precursors, use of expensive or toxic catalysts, the use of a large quantity of volatile and toxic organics, formation of by‐products, product contamination and difficulty in catalyst separation from the reaction media and recycling . Therefore, the search to find a new, green, efficient and reusable catalytic system for the synthesis of polyhydroquinoline structural scaffolds is an important challenge for organic‐synthetic chemists in catalysis research.…”