1262284-06-9Relevant academic research and scientific papers
Neutral Nickel(II) Complexes Bearing Aryloxide Imidazolin-2-imine Ligands for Efficient Copolymerization of Norbornene and Polar Monomers
Li, Mingyuan,Cai, Zhengguo,Eisen, Moris S.
, p. 4753 - 4762 (2018)
A series of novel aryloxide imidazolin-2-imine bidentate neutral Ni(II) complexes with different substituents on the imidazolin-2-imine ligand were synthesized and characterized. The complex Ni2 bearing a 2,6-diisopropylphenyl substituent adopted an almost square planar geometry, while the bulkier 2,6-bis(diphenylmethyl)-4-methylphenyl substituent ligated complex Ni3 was obtained in an allyl adduct base-free η3 coordination mode. In the presence of B(C6F5)3, these Ni(II) complexes exhibited remarkably high activity (up to 2.7 × 107 g of PNB (mol of Ni)-1 h-1) and particularly good thermal stability toward the addition polymerization of norbornene. Most importantly, these catalysts were able to promote the direct copolymerization of norbornene with various polar monomers with high activity (～105 g (mol of Ni)-1 h-1), reasonable comonomer incorporation (0.14-3.08%), and high copolymer molecular weight (Mn up to 2.0 × 105). The strategy of installing a strongly electron donating imidazolin-2-imine ligand on the nickel complex demonstrates a great advantage for the copolymerization of an olefin with polar monomers.
Influence of a very bulky N- Heterocyclic Carbene in Gold-Mediated Catalysis
Gomez-Suarez, Adrian,Ramon, Ruben S.,Songis, Olivier,Slawin, Alexandra M. Z.,Cazin, Catherine S. J.,Nolan, Steven P.
experimental part, p. 5463 - 5470 (2011/12/13)
The syntheses of the free carbene IPr* (IPr* = 1,3-bis(2,6-bis(diphenylmethyl)-4-methylphenyl)imidazol-2-ylidene) and related gold complexes [Au(IPr*)Cl] (C1) and [Au(IPr*)(NTf2)] (C2) were achieved in high yields. The % VBur of IPr* for both gold complexes was measured, revealing IPr* as one of the bulkiest NHCs on gold complexes reported to date. In addition, the catalytic activity of C1 and C2 in several reactions, typically catalyzed by AuI complexes, was investigated. Examples include the tandem alkoxylation/lactonization of γ-hydroxy-α,β-acetylenic esters, the [3,3]-rearrangement of propargylic acetates leading to the formation of conjugated enones and substituted indenes, and the rearrangement of allylic acetates. These studies revealed a strong solvent effect on the catalytic activity with 1,2-dichloroethane as the solvent of choice. The screening of C1 and C2 demonstrated only slightly diminished activities in comparison to [Au(NHC)(L)] complexes bearing bulky ligands such as IPr and SIPr.
