A triphenylsiloxy complex of chromium(II) as a switchable catalyst for ethylene polymerization and nonselective oligomerization

Pengyuan Qiu; Ruihua Cheng; Boping Liu; Boris Tumanskii; Rami J. Batrice; Mark Botoshansky; Moris S. Eisen

doi:10.1021/om101008j

A triphenylsiloxy complex of chromium(II) as a switchable catalyst for ethylene polymerization and nonselective oligomerization

Pengyuan Qiu, Ruihua Cheng, Boping Liu^*, Boris Tumanskii, Rami J. Batrice, Mark Botoshansky, Moris S. Eisen

^*Corresponding author for this work

Research output: Contribution to journal › Article › peer-review

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Abstract

A novel dinuclear oxygen-bridged chromium(II) complex of [(Ph ₃SiO)Cr•(THF)]₂(μ-OSiPh₃)₂ (1) was successfully synthesized and structurally characterized. The crystal structure of complex 1 shows that the chromium centers adopt a tetrahedrally distorted square-planar coordination geometry. Complex 1 was tested for ethylene polymerization upon activation with and without aluminum alkyl cocatalysts. No ethylene polymerization activity was observed in the absence of aluminum alkyl cocatalysts; however, in the presence of methylaluminoxane (MAO), complex 1 demonstrates an unexpected transformation from ethylene polymerization to ethylene oligomerization, with the molar ratio of Al to Cr increasing from 50 to 1000. The activation of complex 1 with MAO was investigated by ESR and ²⁹Si NMR spectroscopy. It was found that the Ph₃SiO- groups could be transferred from the chromium centers of complex 1 to the aluminum of MAO.

Original language	English
Pages (from-to)	2144-2148
Number of pages	5
Journal	Organometallics
Volume	30
Issue number	8
DOIs	https://doi.org/10.1021/om101008j
State	Published - 25 Apr 2011
Externally published	Yes

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title = "A triphenylsiloxy complex of chromium(II) as a switchable catalyst for ethylene polymerization and nonselective oligomerization",

abstract = "A novel dinuclear oxygen-bridged chromium(II) complex of [(Ph 3SiO)Cr•(THF)]2(μ-OSiPh3)2 (1) was successfully synthesized and structurally characterized. The crystal structure of complex 1 shows that the chromium centers adopt a tetrahedrally distorted square-planar coordination geometry. Complex 1 was tested for ethylene polymerization upon activation with and without aluminum alkyl cocatalysts. No ethylene polymerization activity was observed in the absence of aluminum alkyl cocatalysts; however, in the presence of methylaluminoxane (MAO), complex 1 demonstrates an unexpected transformation from ethylene polymerization to ethylene oligomerization, with the molar ratio of Al to Cr increasing from 50 to 1000. The activation of complex 1 with MAO was investigated by ESR and 29Si NMR spectroscopy. It was found that the Ph3SiO- groups could be transferred from the chromium centers of complex 1 to the aluminum of MAO.",

author = "Pengyuan Qiu and Ruihua Cheng and Boping Liu and Boris Tumanskii and Batrice, {Rami J.} and Mark Botoshansky and Eisen, {Moris S.}",

year = "2011",

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T1 - A triphenylsiloxy complex of chromium(II) as a switchable catalyst for ethylene polymerization and nonselective oligomerization

AU - Qiu, Pengyuan

AU - Cheng, Ruihua

AU - Liu, Boping

AU - Tumanskii, Boris

AU - Batrice, Rami J.

AU - Botoshansky, Mark

AU - Eisen, Moris S.

PY - 2011/4/25

Y1 - 2011/4/25

N2 - A novel dinuclear oxygen-bridged chromium(II) complex of [(Ph 3SiO)Cr•(THF)]2(μ-OSiPh3)2 (1) was successfully synthesized and structurally characterized. The crystal structure of complex 1 shows that the chromium centers adopt a tetrahedrally distorted square-planar coordination geometry. Complex 1 was tested for ethylene polymerization upon activation with and without aluminum alkyl cocatalysts. No ethylene polymerization activity was observed in the absence of aluminum alkyl cocatalysts; however, in the presence of methylaluminoxane (MAO), complex 1 demonstrates an unexpected transformation from ethylene polymerization to ethylene oligomerization, with the molar ratio of Al to Cr increasing from 50 to 1000. The activation of complex 1 with MAO was investigated by ESR and 29Si NMR spectroscopy. It was found that the Ph3SiO- groups could be transferred from the chromium centers of complex 1 to the aluminum of MAO.

AB - A novel dinuclear oxygen-bridged chromium(II) complex of [(Ph 3SiO)Cr•(THF)]2(μ-OSiPh3)2 (1) was successfully synthesized and structurally characterized. The crystal structure of complex 1 shows that the chromium centers adopt a tetrahedrally distorted square-planar coordination geometry. Complex 1 was tested for ethylene polymerization upon activation with and without aluminum alkyl cocatalysts. No ethylene polymerization activity was observed in the absence of aluminum alkyl cocatalysts; however, in the presence of methylaluminoxane (MAO), complex 1 demonstrates an unexpected transformation from ethylene polymerization to ethylene oligomerization, with the molar ratio of Al to Cr increasing from 50 to 1000. The activation of complex 1 with MAO was investigated by ESR and 29Si NMR spectroscopy. It was found that the Ph3SiO- groups could be transferred from the chromium centers of complex 1 to the aluminum of MAO.

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JO - Organometallics

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ER -

A triphenylsiloxy complex of chromium(II) as a switchable catalyst for ethylene polymerization and nonselective oligomerization

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