4 years ago

trans-Mutation at Gold(III): A Mechanistic Study of a Catalytic Acetylene Functionalization via a Double Insertion Pathway

trans-Mutation at Gold(III): A Mechanistic Study of a Catalytic Acetylene Functionalization via a Double Insertion Pathway
Mats Tilset, Richard H. Heyn, Sigurd Øien-Ødegaard, Ainara Nova, David Balcells, Gábor Laurenczy, Eirin Langseth, Marte Sofie Martinsen Holmsen
The Au(III) complex Au(tpy)(OAcF)2 (OAcF = OCOCF3; tpy = 2-(p-tolyl)pyridine) catalyzes the anti addition of trifluoroacetic acid (HOAcF) to acetylene to furnish vinyl trifluoroacetate. The Au(III) vinyl complex Au(tpy)(OAcF)(CH═CHOAcF) (vinyl group bonded trans to tpy-N) is formed during the early stage of the reaction. The vinyl complex, which has been isolated and structurally characterized, resists protolytic cleavage of the vinyl group, and therefore catalysis does not proceed by a simple formal insertion (i.e., coordination-nucleophilic attack-protolysis at the site trans to tpy-N) mechanism. Experimental evidence, including isotopic labeling, rather suggests that a double-insertion process is operative. The unobserved Au(III) divinyl complex Au(tpy)(CH═CHOAcF)2 is a crucial intermediate for which the true catalytic activity, comprising a coordination-nucleophilic attack-protolysis sequence, occurs at the site trans to tpy-C. The overall mechanism is in full agreement with DFT calculations and is a result of the considerable differences in the kinetic and thermodynamic trans effects of tpy-N versus tpy-C on each reaction step. The computational data provide a rationale for the catalytic functionalization of acetylene trans to tpy-C, whereas ethylene (previously reported) only undergoes a stoichiometric insertion, and then comes to a full stop, trans to tpy-N.

Publisher URL: http://dx.doi.org/10.1021/acscatal.7b01364

DOI: 10.1021/acscatal.7b01364

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.