Acid-catalyzed oxidative addition of a C-H bond to a square planar d 8 Iridium Complex

Jason D. Hackenberg, Sabuj Kundu, Thomas J. Emge, Karsten Krogh-Jespersen, Alan S. Goldman

Research output: Contribution to journalArticlepeer-review

15 Scopus citations

Abstract

While the addition of C-H bonds to three-coordinate Ir(I) fragments is a central theme in the field of C-H bond activation, addition to square planar four-coordinate complexes is far less precedented. The dearth of such reactions may be attributed, at least in part, to kinetic factors elucidated in seminal work by Hoffmann. C-H additions to square planar carbonyl complexes in particular are unprecedented, in contrast to the extensive chemistry of oxidative addition of other substrates (e.g., H2, HX) to Vaska's Complex and related species. We report that Bronsted acids will catalyze the addition of the alkynyl C-H bond of phenylacetylene to the pincer complex (PCP)Ir(CO). The reaction occurs to give exclusively the trans-C-H addition product. Our proposed mechanism, based on kinetics and DFT calculations, involves initial protonation of (PCP)Ir(CO) to generate a highly active five-coordinate cationic intermediate, which forms a phenylacetylene adduct that is then deprotonated to give product.

Original languageEnglish (US)
Pages (from-to)8891-8894
Number of pages4
JournalJournal of the American Chemical Society
Volume136
Issue number25
DOIs
StatePublished - Jun 25 2014

All Science Journal Classification (ASJC) codes

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

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