Improving intramolecular hydroamination Rh(I) and Ir(I) catalysts through targeted ligand modification

Sophie R. Beeren, Serin L. Dabb, Gavin Edwards, Matthew K. Smith, Anthony C. Willis, Barbara A. Messerle

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

A series of complexes containing the phosphino-pyrazolyl ligand 1-(2-(diphenylphosphino) phenyl) pyrazole (PyPhP) and 1-(2-(diphenylphosphino) ethyl) pyrazole (PyP) were synthesized: [Ir(PyPhP)(COD)]BPh4, [Ir(PyPhP)(CO)2] BPh4, Rh(PyPhP)(CO)Cl and Ir(PyPhP)(CO)Cl. The complexes Rh(PyP)(CO)OSO2CF3 and Rh(PyPhP)(CO)OSO2CF3 were also synthesized, using the parent complexes Rh(PyP)(CO)Cl and Rh(PyPhP)(CO)Cl. The solid-state structures of the new complexes were determined by X-ray diffraction analysis. The cationic Ir(I) complex [Ir(PyPhP)(COD)]BPh4 was found to be a highly efficient catalyst for the intramolecular hydroamination of 4-pentyn-1-amine, achieving a turnover rate of 1500 h-1, with >98% conversion in 6 minutes. The efficiency of the catalyzed hydroamination of 4-pentyn-1-amine using the neutral Ir(I) and Rh(I) complexes as catalysts was significantly improved by generating active catalysts in situ through abstraction of a chloride ligand by reaction with AgOSO2CF3, TMSOSO2CF3 or NaBPh4. The catalytic efficiency of the catalysts generated from Ir(PyP)(CO)Cl and a sodium salt were found to be inversely proportional to the coordinating strength of the counter-ion of the sodium salt. Rh(PyP)(CO)OSO2CF3 is a more efficient catalyst for thecyclization of 4-pentyn-1-amine than the complex generated in situ from AgOSO2CF3 and chloride complex Rh(PyP)(CO)Cl indicating that the higher lability of the triflate co-ligand of Rh(PyP)(CO)OSO2CF3, compared to the chloride co-ligand of Rh(PyP)(CO)Cl, enhances the catalytic activity of the Rh(I) complexes.
Original languageEnglish
JournalNew Journal of Chemistry
Volume34
Issue number6
Pages (from-to)1200-1208
Number of pages9
ISSN1144-0546
DOIs
Publication statusPublished - 2010
Externally publishedYes

Keywords

  • Chemistry (all)
  • Catalysis
  • Materials Chemistry
  • amine
  • chloride
  • ion
  • iridium
  • ligand
  • pyrazole derivative
  • rhodium
  • sodium
  • amination
  • article
  • catalysis
  • catalyst
  • chemical modification
  • chemical reaction
  • chemical structure
  • cyclization
  • priority journal
  • solid state
  • synthesis
  • turnover time
  • X ray diffraction
  • CHEMISTRY,
  • ANTI-MARKOVNIKOV HYDROAMINATION
  • IRIDIUM(I) COMPLEXES
  • INTERMOLECULAR HYDROAMINATION
  • UNACTIVATED ALKENES
  • METAL-COMPLEXES
  • ALKYNES
  • RHODIUM
  • WATER
  • CALCIUM
  • AMINOALKENES

Fingerprint Dive into the research topics of 'Improving intramolecular hydroamination Rh(I) and Ir(I) catalysts through targeted ligand modification'. Together they form a unique fingerprint.

Cite this