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 journal › Article

11 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

Fingerprint

Iridium
Alkanes
Dehydrogenation
dehydrogenation
iridium
Paraffins
alkanes
octanes
catalytic activity
Catalyst activity
Ligands
Regioselectivity
ligands
Catalyst selectivity
Alkenes
alkenes
Olefins
Hydrogen
selectivity
Sodium

Keywords

  • Alkane
  • Alkene
  • Dehydrogenation
  • Homogeneous catalysis
  • Iridium

ASJC Scopus subject areas

  • Inorganic Chemistry
  • Materials Chemistry
  • Physical and Theoretical Chemistry

Cite this

Catalytic alkane transfer-dehydrogenation by PSCOP iridium pincer complexes. / Yao, Wubing; Jia, Xiangqing; Leng, Xuebing; Goldman, Alan S; Brookhart, Maurice; Huang, Zheng.

In: Polyhedron, 19.01.2016.

Research output: Contribution to journal › Article

Yao, W, Jia, X, Leng, X, Goldman, AS, Brookhart, M & Huang, Z 2016, 'Catalytic alkane transfer-dehydrogenation by PSCOP iridium pincer complexes', Polyhedron. https://doi.org/10.1016/j.poly.2016.02.044
Yao W, Jia X, Leng X, Goldman AS, Brookhart M, Huang Z. Catalytic alkane transfer-dehydrogenation by PSCOP iridium pincer complexes. Polyhedron. 2016 Jan 19. https://doi.org/10.1016/j.poly.2016.02.044
Yao, Wubing ; Jia, Xiangqing ; Leng, Xuebing ; Goldman, Alan S ; Brookhart, Maurice ; Huang, Zheng. / Catalytic alkane transfer-dehydrogenation by PSCOP iridium pincer complexes. In: Polyhedron. 2016.
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AU - Goldman, Alan S

AU - Brookhart, Maurice

AU - Huang, Zheng

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N2 - 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.

AB - 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.

KW - Alkane

KW - Alkene

KW - Dehydrogenation

KW - Homogeneous catalysis

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