Facile Hydrolysis of Nickel(II) Complexes with N-Heterocyclic Carbene Ligands
摘要:
Metal complexes with N-heterocyclic carbene ligands (NHC) are ubiquitously used in catalysis, where the stability of the metal-ligand framework is a key issue. Our study shows that Ni-NHC complexes may undergo facile decomposition due to the presence of water in organic solvents (hydrolysis). The ability to hydrolyze Ni(NHC)(2)X-2 complexes decreases in the order of NHC = 1,2,4-triazolium > benzimidazolium approximate to imidazolium. Depending on the ligand and substituents, the half reaction time of the complex decomposition may change from several minutes to hours. The nature of the halogen is also an important factor, and the ability for decomposition of the studied complexes decreases in the order of Cl > Br > I. NMR and MS monitoring revealed that Ni-NHC complexes in the presence of water undergo hydrolysis with Ni-C-carbene bond cleavage, affording the corresponding N,N'-dialkylated azolium salts and nickel(II) hydroxide. These findings are of great importance for designing efficient and recyclable catalytic systems, because trace water is a common contaminant in routine synthetic applications.
[NiX
<sub>2</sub>
(NHC)
<sub>2</sub>
] Complexes in the Hydrosilylation of Internal Alkynes
作者:Joris Berding、John A. van Paridon、Vincent H. S. van Rixel、Elisabeth Bouwman
DOI:10.1002/ejic.201100015
日期:2011.5
A number of nickel(II) dihalide complexes with small monodentate N-heterocyclic carbene ligands was synthesized and tested for their catalytic activity in the hydrosilylation of internal alkynes. The nickel(0) active species was obtained from the starting nickel(II) complex by reduction with diethylzinc. In all cases the catalytic reaction yielded the syn product selectively. The fastest catalysts
Facile Hydrolysis of Nickel(II) Complexes with N-Heterocyclic Carbene Ligands
作者:Alexander V. Astakhov、Oleg V. Khazipov、Evgeniya S. Degtyareva、Victor N. Khrustalev、Victor M. Chernyshev、Valentine P. Ananikov
DOI:10.1021/acs.organomet.5b00856
日期:2015.12.28
Metal complexes with N-heterocyclic carbene ligands (NHC) are ubiquitously used in catalysis, where the stability of the metal-ligand framework is a key issue. Our study shows that Ni-NHC complexes may undergo facile decomposition due to the presence of water in organic solvents (hydrolysis). The ability to hydrolyze Ni(NHC)(2)X-2 complexes decreases in the order of NHC = 1,2,4-triazolium > benzimidazolium approximate to imidazolium. Depending on the ligand and substituents, the half reaction time of the complex decomposition may change from several minutes to hours. The nature of the halogen is also an important factor, and the ability for decomposition of the studied complexes decreases in the order of Cl > Br > I. NMR and MS monitoring revealed that Ni-NHC complexes in the presence of water undergo hydrolysis with Ni-C-carbene bond cleavage, affording the corresponding N,N'-dialkylated azolium salts and nickel(II) hydroxide. These findings are of great importance for designing efficient and recyclable catalytic systems, because trace water is a common contaminant in routine synthetic applications.
Synthesis and Reactivity of Remarkably Stable and Nucleophilic Hydroxide-Bridged Dimetallic Nickel NHC Complexes
作者:Simone Bertini、Martin Albrecht
DOI:10.1021/acs.organomet.0c00495
日期:2020.9.28
of these bimetallic complexes with CH3+ as an electrophile (MeOTf) induced alkylation of the bridging hydroxide ligands and afforded the new alkoxy-bridged complexes [(NHC)2Ni(μ-OMe)2Ni(NHC)2]2+. In contrast, reactions of [(imi)2Ni(μ-OH)2Ni(imi)2]2+ with H+ as electrophile (mild acids with pKa > 6) led to cleavage of the dimeric structure and formation of mononuclear complexes [Ni(X)2(imi)2]. Conversely