Air stable pincer (CNC) N-heterocyclic carbene–cobalt complexes and their application as catalysts for C–N coupling reactions

Ibrahim, Halliru; Bala, Muhammad D.

doi:10.1016/j.jorganchem.2015.07.015

Cited by 23 publications

(7 citation statements)

References 52 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Relating the trend in catalytic activity to the structures of the complexes; the major structural difference between the most active catalyst 3 , and the other catalysts ( 4 , 7 and 8 ) is the pyridyl side group in its framework, which has the potential to enhance its stability as a secondary or hemilabile donor arm during catalysis hence leading to better substrate conversion. Similar trends have been noted for highly active catalysts bearing related structural motifs [ 43 , 44 ]. However, the catalytic efficiencies of complexes 7 and 8 in terms of selectivity to benzaldehyde are similar to the trends observed in Ni(II) complexes bearing sterically modified linear tetradentate N4 ligands reported by Sankaralingam et al [ 45 ].…”

Section: Resultssupporting

confidence: 82%

“…However, when the substrate concentration was varied while other parameters were kept constant, as expected, the kinetic order of the reaction was observed to decrease with an increase in styrene concentration. With catalyst concentration kept constant, an increase in styrene concentration led to a dilution effect that negatively affected the availability of the metal centre, thereby leading to the observed decrease in the conversion of styrene ( Figure 8 ) [ 44 , 48 ].…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Oxidation of Styrene to Benzaldehyde Catalyzed by Schiff Base Functionalized Triazolylidene Ni(II) Complexes

2022

Self Cite

View full text Add to dashboard Cite

Four new Schiff base functionalized 1,2,3-triazolylidene nickel complexes, [Ni-(L1NHC)2](PF6)2; 3, [Ni-(L2NHC)2](PF6)2; 4, [Ni-(L3NHC)](PF6)2; 7 and [Ni-(L4NHC)](PF6)2; 8, (where L1NHC = (E)-3-methyl-1-propyl-4-(2-(((2-(pyridin-2-yl)ethyl)imino)methyl)phenyl)-1H-1,2,3-triazol-3-ium hexafluorophosphate(V), 1, L2NHC = (E)-3-methyl-4-(2-((phenethylimino)methyl)phenyl)-1-propyl-1H-1,2,3-triazol-3-ium hexafluorophosphate(V), 2, L3NHC = 4,4′-(((1E)-(ethane-1,2-diylbis(azanylylidene))bis(methanylylidene))bis(2,1-phenylene))bis(3-methyl-1-propyl-1H-1,2,3-triazol-3-ium) hexafluorophosphate(V), 5, and L4NHC = 4,4′-(((1E)-(butane-1,4-diylbis(azanylylidene))bis(methanylylidene))bis(2,1-phenylene))bis(3-methyl-1-propyl-1H-1,2,3-triazol-3-ium) hexafluorophosphate(V), 6), were synthesised and characterised by a variety of spectroscopic methods. Square planar geometry was proposed for all the nickel complexes. The catalytic potential of the complexes was explored in the oxidation of styrene to benzaldehyde, using hydrogen peroxide as a green oxidant in the presence of acetonitrile at 80 °C. All complexes showed good catalytic activity with high selectivity to benzaldehyde. Complex 3 gave a conversion of 88% and a selectivity of 70% to benzaldehyde in 6 h. However, complexes 4 and 7–8 gave lower conversions of 48–74% but with higher (up to 90%) selectivity to benzaldehyde. Results from kinetics studies determined the activation energy for the catalytic oxidation reaction as 65 ± 3 kJ/mol, first order in catalyst and fractional order in the oxidant. Results from UV-visible and CV studies of the catalytic activity of the Ni-triazolylidene complexes on styrene oxidation did not indicate any clear possibility of generation of a Ni(II) to Ni(III) catalytic cycle.

show abstract

Section: Resultssupporting

confidence: 82%

Section: Resultsmentioning

confidence: 99%

Oxidation of Styrene to Benzaldehyde Catalyzed by Schiff Base Functionalized Triazolylidene Ni(II) Complexes

2022

Self Cite

View full text Add to dashboard Cite

show abstract

“…The reaction of [Ag 2 (C^N^C)Cl 2 ] with [Ru(PPh 3 ) 3 Cl 2 ] followed by treatment with a panel of R 2 bpy ligands ( H =bpy; Me =4,4′‐dimethyl‐bpy; OMe =4,4′‐dimethoxy‐bpy; t Bu =4,4′‐di‐ tert ‐butyl‐bpy) gave [Ru II (C^N^C)(R 2 bpy)Cl] + ( 1′ ) in 43–52 % yields ( 1′‐H , 50 %; 1′‐Me , 51 %; 1′‐OMe 52 %; 1′‐ t Bu , 43 %). The subsequent reaction of 1′ with AgOTf in MeCN afforded 1 (Scheme ) in 71–80 % yields ( 1‐H , 80 %; 1‐Me , 78 %; 1‐OMe 73 %; 1‐ t Bu , 71 %).…”

Section: Methodsmentioning

confidence: 68%

Intramolecular Nitrene Insertion into Saturated C−H‐Bond‐Mediated C−N Bond Cleavage of a Coordinated NHC Ligand

Liu

Tse

Lam

et al. 2019

Chemistry A European J

View full text Add to dashboard Cite

Ruthenium(II) complexes bearing a tridentate bis(N‐heterocyclic carbene) ligand reacted with iminoiodanes (PhI=NR) resulting in the formation of isolable ruthenium(III)–amido intermediates, which underwent cleavage of a C−N bond of the tridentate ligand and formation of an N‐substituted imine group. The RuIII–amido intermediates have been characterized by 1H NMR, UV/Vis, ESI‐MS, and X‐ray crystallography. DFT calculations were performed to provide insight into the reaction mechanism.

show abstract

“…It was found that the use of a catalyst PS-Co(BBZN)Cl2, in combination with some ligands provided a robust catalytic system. On the basis of previous mechanistic studies in cobalt-catalyzed C−N bond formation reactions, it was possible to propose a mechanism for the conversion of 3-(adamantan-1-yl)-N-(4-chlorophenyl)-4-methoxyaniline (3 a) as shown in Figure 3 [32][33][34]. Initially, the catalyst makes a complex with amine to form a catalyst-amine complex A, which undergoes an oxidative addition reaction with 1-(5-bromo-2-methoxyphenyl)adamantane and complex B formation occurs.…”

Section: Entry Aromatic Halomentioning

confidence: 99%

Development of a New Arylamination Reaction Catalyzed by Polymer Bound 1,3-(Bisbenzimidazolyl) Benzene Co(II) Complex and Generation of Bioactive Adamanate Amines

et al. 2020

View full text Add to dashboard Cite

We herein report the preparation and characterization of an inexpensive polymer supported 1,3-bis(benzimidazolyl)benzeneCo(II) complex [PS-Co(BBZN)Cl2] as a catalyst by using the polymer (divinylbenzene cross-linked chloromethylated polystyrene), on which 1,3-bis(benzimidazolyl)benzeneCo(II) complex (PS-Co(BBZN)Cl2) has been immobilized. This catalyst was employed to develop arylamination reaction and robustness of the same reaction was demonstrated by synthesizing various bioactive adamantanyl-tethered-biphenylamines. Our synthetic methodology was much improved than reported methods due to the use of an inexpensive and recyclable catalyst.

show abstract

Air stable pincer (CNC) N-heterocyclic carbene–cobalt complexes and their application as catalysts for C–N coupling reactions

Cited by 23 publications

References 52 publications

Oxidation of Styrene to Benzaldehyde Catalyzed by Schiff Base Functionalized Triazolylidene Ni(II) Complexes

Oxidation of Styrene to Benzaldehyde Catalyzed by Schiff Base Functionalized Triazolylidene Ni(II) Complexes

Intramolecular Nitrene Insertion into Saturated C−H‐Bond‐Mediated C−N Bond Cleavage of a Coordinated NHC Ligand

Development of a New Arylamination Reaction Catalyzed by Polymer Bound 1,3-(Bisbenzimidazolyl) Benzene Co(II) Complex and Generation of Bioactive Adamanate Amines

Contact Info

Product

Resources

About