3 years ago

(α-Diimine)nickel Complexes That Contain Menthyl Substituents: Synthesis, Conformational Behavior, and Olefin Polymerization Catalysis

(α-Diimine)nickel Complexes That Contain Menthyl Substituents: Synthesis, Conformational Behavior, and Olefin Polymerization Catalysis
Richard F. Jordan, Feng Zhai
We describe the synthesis and coordination chemistry of the (1R,2S,5R)-menthyl-substituted N,N′-diaryl-α-diimine ligands N,N′-(2-Men-4-Me-Ph)2-BIAN (L1, Men = menthyl, BIAN = bis(imino)acenaphthene) and N,N′-(2-Men-4,6-Me2-Ph)2-BIAN (L2), the conformational properties of these ligands and their metal complexes, and the ethylene and 1-hexene polymerization behavior of the corresponding (α-diimine)Ni complexes. Free ligands L1 and L2 and square-planar (L1)PdCl2 and (L1,2)Ni(acac)+ complexes exhibit a preference for the syn conformation, in which the two menthyl units are located on the same side of the N═CC═N plane, while tetrahedral (L1,2)MX2 (MX2 = ZnCl2, NiBr2) complexes exhibit a preference for the anti conformation, in which the menthyl units are located on opposite sides of the N═CC═N plane. Both the anti and the syn conformers of [(L2)Ni(acac)][B(C6F5)4] can be activated by Et2AlCl to generate highly active ethylene polymerization catalysts (activity (2.5–6.6) × 106 g of PE/((mol of Ni) h) at 15 psi of C2H4, room temperature). The polyethylene produced by the syn conformer (syn/anti = 91/9) has a higher molecular weight (2×) and a higher branch density (3×) in comparison to that produced by the anti conformer. The polyhexene produced by the syn conformer (syn/anti = 91/9) contains a higher level of chain straightening (syn 50%, anti 41%) and a higher percentage of Me versus Bu branches (syn 24/26, anti 6/53) in comparison to that produced by the anti isomer. These results are indicative of a greater preference for 2,1-insertion and for chain walking (versus growth) following 1,2-insertion for the syn conformer.

Publisher URL: http://dx.doi.org/10.1021/acs.organomet.7b00283

DOI: 10.1021/acs.organomet.7b00283

You might also like
Discover & Discuss Important Research

Keeping up-to-date with research can feel impossible, with papers being published faster than you'll ever be able to read them. That's where Researcher comes in: we're simplifying discovery and making important discussions happen. With over 19,000 sources, including peer-reviewed journals, preprints, blogs, universities, podcasts and Live events across 10 research areas, you'll never miss what's important to you. It's like social media, but better. Oh, and we should mention - it's free.

  • Download from Google Play
  • Download from App Store
  • Download from AppInChina

Researcher displays publicly available abstracts and doesn’t host any full article content. If the content is open access, we will direct clicks from the abstracts to the publisher website and display the PDF copy on our platform. Clicks to view the full text will be directed to the publisher website, where only users with subscriptions or access through their institution are able to view the full article.