Catalytic alkane transfer-dehydrogenation by PSCOP iridium pincer complexes

Wubing Yao, Xiangqing Jia, Xuebing Leng, Alan S Goldman, Maurice Brookhart, Zheng Huang

Research output: Contribution to journalArticle

15 Citations (Scopus)

Abstract

A series of new ( t Bu2PSCOPR2)IrHCl iridium complexes with 'hybrid' phosphinothious-phosphinite PSCOP ligands ([ t Bu2PSCOPR2 =1-(SPtBu2)-3-(OPR2)-C6H4], R= tBu, 4a, R=Cy, 4b, R= iPr, 4c, and R=Et, 4d) have been synthesized and characterized. Treatment of complexes 4a-d with sodium tert-butoxide generates the active species for catalytic transfer-dehydrogenation of cyclooctane (COA) or n-octane using tert-butylethylene (TBE) as hydrogen acceptor to form cyclooctene (COE) or octenes, respectively. The catalytic activity of these complexes and the product selectivity in alkane dehydrogenation is greatly influenced by the steric properties of the pincer ligand. In general, the less sterically bulky complex exhibits higher catalytic activity than the more hindered complex. Among the new (PSCOP)Ir-type complexes, the least crowded complex ( t Bu2PSCOPEt2)IrHCl 4d is most active for n-octane/TBE transfer-dehydrogenation. The relatively crowded, less active, complexes ( t Bu2PSCOP t Bu2)IrHCl (4a) and ( t Bu2PSCOPCy2)IrHCl (4b) exhibit high regioselectivity for α-olefin formation at the early stages of the reaction.

Original languageEnglish
JournalPolyhedron
DOIs
Publication statusAccepted/In press - Jan 19 2016

Keywords

  • Alkane
  • Alkene
  • Dehydrogenation
  • Homogeneous catalysis
  • Iridium

ASJC Scopus subject areas

  • Inorganic Chemistry
  • Materials Chemistry
  • Physical and Theoretical Chemistry

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