Isomerization of internal alkynes to iridium(III) allene complexes via C-H bond activation: Expanded substrate scope, and progress towards a catalytic methodology

Neha Phadke, Michael Findlater

Research output: Contribution to journalArticle

2 Scopus citations

Abstract

The synthesis of a series of allene complexes (POCOP)Ir(ç2 -RC==CR') 1b-4b (POCOP = 2,6-bis(di-tert-butylphosphonito)benzene) via isomerization of internal alkynes is reported. We have demonstrated that the application of this methodology is viable for the isomerization of a wide variety of alkyne substrates. Deuterium labeling experiments support our proposed mechanism. The structures of the allene complexes 1b-4b were determined using spectroscopic data analysis. Additionally, the solid-state molecular structure of complex 2b was determined using single crystal X-ray diffraction studies and it confirmed the assignment of an iridium-bound allene isomerization product. The rates of isomerization were measured using NMR techniques over a range of temperatures to allow determination of thermodynamic parameters. Finally, we report a preliminary step towards developing a catalytic methodology; the allene may be liberated from the metal center by exposure of the complex to an atmosphere of carbon monoxide.

Original languageEnglish
Pages (from-to)20195-20205
Number of pages11
JournalMolecules
Volume20
Issue number11
DOIs
StatePublished - Nov 10 2015

Keywords

  • Allenes
  • Crystal structure
  • Iridium
  • Isolation
  • Isomerization
  • Pincer
  • Synthesis

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