Exclusive C-C activation and an apparent α-H elimination with a rhodium phosphinite pincer complex

Hiyam Salem; Yehoshoa Ben-David; Linda J.W. Shimon; David Milstein

doi:10.1021/om060005q

Exclusive C-C activation and an apparent α-H elimination with a rhodium phosphinite pincer complex

Hiyam Salem, Yehoshoa Ben-David, Linda J.W. Shimon, David Milstein

Weizmann Institute of Science, Israel

Research output: Contribution to journal › Article

70 Citations (Scopus)

Abstract

Exclusive C-C bond activation involving the new bisphosphinite ligand {C₆H₃(CH₃)[OP(ⁱPr)₂] ₂} (1) was observed at room temperature, upon reaction with the cationic complex [Rh(COE)₂(THF)₂]BF₄ (COE = cyclooctene) in THF, yielding the Rh(III) complex [(POCOP)Rh(Me)]BF₄ (2) (POCOP = C₆H₃[OP(ⁱPr)₂] ₂). No parallel C-H activation was observed. This preference is assumed to be governed by the better directed phosphinite-bound metal center toward the C-C bond. A single-crystal X-ray diffraction analysis of complex 2 revealed a square pyramidal geometry with the BF₄^- ion coordinated to the metal center. Complex 2 reacted with H₂ at room temperature in THF to yield the Rh(III)-hydrido complex 3 and methane. Deprotonation of 3 with KO^tBu yielded the Rh(I) dinitrogen complex [(POCOP)Rh]₂(μ-N₂) (4), which upon reaction with 1 equiv of CO or ethylene formed (POCOP)Rh(CO) (5) or (POCOP)Rh-(C ₂H₄) (6), respectively. Complex 4 readily underwent oxidative addition of Mel, benzyl chloride, and benzyl bromide, forming complexes 7, 8, and 9, respectively. Halide abstraction from complex 9 with AgBF₄ led to the cationic benzyl complex 12, bearing a coordinated BF₄^- ion as observed by a single-crystal X-ray diffraction analysis. Finally, we report an apparent α-H elimination from Rh(III)-Me, which takes place upon heating of the C-C activation product 2 at 150°C in the solid state, yielding the hydride complex 3 and ethylene.

Original language	English
Pages (from-to)	2292-2300
Number of pages	9
Journal	Organometallics
Volume	25
Issue number	9
DOIs	https://doi.org/10.1021/om060005q
Publication status	Published - Apr 24 2006

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ASJC Scopus subject areas

Physical and Theoretical Chemistry
Organic Chemistry
Inorganic Chemistry

Cite this

Salem, H., Ben-David, Y., Shimon, L. J. W., & Milstein, D. (2006). Exclusive C-C activation and an apparent α-H elimination with a rhodium phosphinite pincer complex. Organometallics, 25(9), 2292-2300. https://doi.org/10.1021/om060005q

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title = "Exclusive C-C activation and an apparent α-H elimination with a rhodium phosphinite pincer complex",

abstract = "Exclusive C-C bond activation involving the new bisphosphinite ligand {C6H3(CH3)[OP(iPr)2] 2} (1) was observed at room temperature, upon reaction with the cationic complex [Rh(COE)2(THF)2]BF4 (COE = cyclooctene) in THF, yielding the Rh(III) complex [(POCOP)Rh(Me)]BF4 (2) (POCOP = C6H3[OP(iPr)2] 2). No parallel C-H activation was observed. This preference is assumed to be governed by the better directed phosphinite-bound metal center toward the C-C bond. A single-crystal X-ray diffraction analysis of complex 2 revealed a square pyramidal geometry with the BF4- ion coordinated to the metal center. Complex 2 reacted with H2 at room temperature in THF to yield the Rh(III)-hydrido complex 3 and methane. Deprotonation of 3 with KOtBu yielded the Rh(I) dinitrogen complex [(POCOP)Rh]2(μ-N2) (4), which upon reaction with 1 equiv of CO or ethylene formed (POCOP)Rh(CO) (5) or (POCOP)Rh-(C 2H4) (6), respectively. Complex 4 readily underwent oxidative addition of Mel, benzyl chloride, and benzyl bromide, forming complexes 7, 8, and 9, respectively. Halide abstraction from complex 9 with AgBF4 led to the cationic benzyl complex 12, bearing a coordinated BF4- ion as observed by a single-crystal X-ray diffraction analysis. Finally, we report an apparent α-H elimination from Rh(III)-Me, which takes place upon heating of the C-C activation product 2 at 150°C in the solid state, yielding the hydride complex 3 and ethylene.",

author = "Hiyam Salem and Yehoshoa Ben-David and Shimon, {Linda J.W.} and David Milstein",

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T1 - Exclusive C-C activation and an apparent α-H elimination with a rhodium phosphinite pincer complex

AU - Salem, Hiyam

AU - Ben-David, Yehoshoa

AU - Shimon, Linda J.W.

AU - Milstein, David

PY - 2006/4/24

Y1 - 2006/4/24

N2 - Exclusive C-C bond activation involving the new bisphosphinite ligand {C6H3(CH3)[OP(iPr)2] 2} (1) was observed at room temperature, upon reaction with the cationic complex [Rh(COE)2(THF)2]BF4 (COE = cyclooctene) in THF, yielding the Rh(III) complex [(POCOP)Rh(Me)]BF4 (2) (POCOP = C6H3[OP(iPr)2] 2). No parallel C-H activation was observed. This preference is assumed to be governed by the better directed phosphinite-bound metal center toward the C-C bond. A single-crystal X-ray diffraction analysis of complex 2 revealed a square pyramidal geometry with the BF4- ion coordinated to the metal center. Complex 2 reacted with H2 at room temperature in THF to yield the Rh(III)-hydrido complex 3 and methane. Deprotonation of 3 with KOtBu yielded the Rh(I) dinitrogen complex [(POCOP)Rh]2(μ-N2) (4), which upon reaction with 1 equiv of CO or ethylene formed (POCOP)Rh(CO) (5) or (POCOP)Rh-(C 2H4) (6), respectively. Complex 4 readily underwent oxidative addition of Mel, benzyl chloride, and benzyl bromide, forming complexes 7, 8, and 9, respectively. Halide abstraction from complex 9 with AgBF4 led to the cationic benzyl complex 12, bearing a coordinated BF4- ion as observed by a single-crystal X-ray diffraction analysis. Finally, we report an apparent α-H elimination from Rh(III)-Me, which takes place upon heating of the C-C activation product 2 at 150°C in the solid state, yielding the hydride complex 3 and ethylene.

AB - Exclusive C-C bond activation involving the new bisphosphinite ligand {C6H3(CH3)[OP(iPr)2] 2} (1) was observed at room temperature, upon reaction with the cationic complex [Rh(COE)2(THF)2]BF4 (COE = cyclooctene) in THF, yielding the Rh(III) complex [(POCOP)Rh(Me)]BF4 (2) (POCOP = C6H3[OP(iPr)2] 2). No parallel C-H activation was observed. This preference is assumed to be governed by the better directed phosphinite-bound metal center toward the C-C bond. A single-crystal X-ray diffraction analysis of complex 2 revealed a square pyramidal geometry with the BF4- ion coordinated to the metal center. Complex 2 reacted with H2 at room temperature in THF to yield the Rh(III)-hydrido complex 3 and methane. Deprotonation of 3 with KOtBu yielded the Rh(I) dinitrogen complex [(POCOP)Rh]2(μ-N2) (4), which upon reaction with 1 equiv of CO or ethylene formed (POCOP)Rh(CO) (5) or (POCOP)Rh-(C 2H4) (6), respectively. Complex 4 readily underwent oxidative addition of Mel, benzyl chloride, and benzyl bromide, forming complexes 7, 8, and 9, respectively. Halide abstraction from complex 9 with AgBF4 led to the cationic benzyl complex 12, bearing a coordinated BF4- ion as observed by a single-crystal X-ray diffraction analysis. Finally, we report an apparent α-H elimination from Rh(III)-Me, which takes place upon heating of the C-C activation product 2 at 150°C in the solid state, yielding the hydride complex 3 and ethylene.

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10.1021/om060005q