Nickel N-heterocyclic carbene complexes and their utility in homogeneous catalysis

Facile Suzuki-Miyaura coupling of activated aryl halides using new CpNiBr(NHC) complexes

“…This is mainly due to the support that NHCs provide through the possibility of reliable, predictable, and extensive steric-and electronic tuning [2,3b,5-7] in the design of a model complex with the specific application in mind. With the ever-increasing number of transition metal-NHCs reported, NHC-complexes of Rh [3a,8], Ru [9], Ni [7,[10][11][12][13][14], Pd [4a,6b,15,16], Ag [17], and Au [17,18] remain to be the most abundant in literature, noting that Ni-NHC complexes received considerable attention only during the last decade [11,13,14]. The reaction of nickelocene with bis(alkyl/aryl)imidazolium halides to yield the complexes [CpNiX(NHC)] (X = Cl, Br, I), represents one of the most frequently employed and facile routes into cyclopentadienyl nickel(II) NHC systems [7,[11][12][13]19,[21][22].…”

“…In the plethora of C-C coupling reactions, the Suzuki-Miyaura reaction has become one of the most studied for catalytic applications due to its tolerance of functional groups and low toxicity of its by-products [4d, 15,19,20a,25,26]. Furthermore, [CpNiX(NHC)] (X = halide) and related systems have provided equal or improved catalytic activity in some C-C coupling reactions when compared to the traditional Pd catalysts [10,12,20,25,27]. In spite of this, the bromo complexes in the series of [CpNiBr(NHC)] compounds reported are few when compared to their chloro-and iodo-analogues [10,19].…”

“…Furthermore, [CpNiX(NHC)] (X = halide) and related systems have provided equal or improved catalytic activity in some C-C coupling reactions when compared to the traditional Pd catalysts [10,12,20,25,27]. In spite of this, the bromo complexes in the series of [CpNiBr(NHC)] compounds reported are few when compared to their chloro-and iodo-analogues [10,19]. The known [CpNiBr(NHC)] complexes (NHC = imidazolium backbone) reported to date have been illustrated in Figure 1.…”

Immobilization of nickel ions onto the magnetic nanocomposite based on cross‐linked melamine groups: Effective heterogeneous catalyst for N‐Arylation of Arylboronic acids

“…Nickel catalysts have several advantages over copper catalysts such as lower energy barriers for oxidative addition in cross‐coupling reactions, allowing a wider range of leaving groups, lower price and more eco‐friendly characteristics . So, in the past decade, nickel‐catalyzed aromatic C–N coupling reactions have received more attention than copper ones and made remarkable advances, but these nickel complex catalysts are homogenous and have the problems of separation from the final products …”

“…[30,31] So, in the past decade, nickel-catalyzed aromatic C-N coupling reactions have received more attention than copper ones and made remarkable advances, [32][33][34] but these nickel complex catalysts are homogenous and have the problems of separation from the final products. [35,36] In order to alleviate the mentioned problem, immobilization of homogeneous nickel catalysts on solid supports is an applicable way. [37][38][39] These heterogenization protocols have been usually done on various supports such as silica, [40][41][42] cross-linked polymers, [43,44] magnetic nanoparticle (MNPs), [45][46][47][48] zeolite, [39,49,50] and alumina.…”