Well-Defined Cobalt(I) Dihydrogen Catalyst: Experimental Evidence for a Co(I)/Co(III) Redox Process in Olefin Hydrogenation

Kenan Tokmic; Charles R. Markus; Lingyang Zhu; Alison R. Fout

doi:10.1021/jacs.6b07066

Well-Defined Cobalt(I) Dihydrogen Catalyst: Experimental Evidence for a Co(I)/Co(III) Redox Process in Olefin Hydrogenation

Kenan Tokmic, Charles R. Markus, Lingyang Zhu, Alison R. Fout

Chemistry

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

Abstract

The synthesis of a cobalt dihydrogen Co^I-(H₂) complex prepared from a Co^I-(N₂) precursor supported by a monoanionic pincer bis(carbene) ligand, ^MesCCC (^MesCCC = bis(mesityl-benzimidazol-2-ylidene)phenyl), is described. This species is capable of H₂/D₂ scrambling and hydrogenating alkenes at room temperature. Stoichiometric addition of HCl to the Co^I-(N₂) cleanly affords the Co^III hydridochloride complex, which, upon the addition of Cp₂ZrHCl, evolves hydrogen gas and regenerates the Co^I-(N₂) complex. Furthermore, the catalytic olefin hydrogenation activity of the Co^I species was studied by using multinuclear and parahydrogen (p-H₂) induced polarization (PHIP) transfer NMR studies to elucidate catalytically relevant intermediates, as well as to establish the role of the Co^I-(H₂) in the Co^I/Co^III redox cycle.

Original language	English (US)
Pages (from-to)	11907-11913
Number of pages	7
Journal	Journal of the American Chemical Society
Volume	138
Issue number	36
DOIs	https://doi.org/10.1021/jacs.6b07066
State	Published - Sep 14 2016

ASJC Scopus subject areas

Catalysis
General Chemistry
Biochemistry
Colloid and Surface Chemistry

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10.1021/jacs.6b07066

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title = "Well-Defined Cobalt(I) Dihydrogen Catalyst: Experimental Evidence for a Co(I)/Co(III) Redox Process in Olefin Hydrogenation",

abstract = "The synthesis of a cobalt dihydrogen CoI-(H2) complex prepared from a CoI-(N2) precursor supported by a monoanionic pincer bis(carbene) ligand, MesCCC (MesCCC = bis(mesityl-benzimidazol-2-ylidene)phenyl), is described. This species is capable of H2/D2 scrambling and hydrogenating alkenes at room temperature. Stoichiometric addition of HCl to the CoI-(N2) cleanly affords the CoIII hydridochloride complex, which, upon the addition of Cp2ZrHCl, evolves hydrogen gas and regenerates the CoI-(N2) complex. Furthermore, the catalytic olefin hydrogenation activity of the CoI species was studied by using multinuclear and parahydrogen (p-H2) induced polarization (PHIP) transfer NMR studies to elucidate catalytically relevant intermediates, as well as to establish the role of the CoI-(H2) in the CoI/CoIII redox cycle.",

author = "Kenan Tokmic and Markus, {Charles R.} and Lingyang Zhu and Fout, {Alison R.}",

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T2 - Experimental Evidence for a Co(I)/Co(III) Redox Process in Olefin Hydrogenation

AU - Tokmic, Kenan

AU - Markus, Charles R.

AU - Zhu, Lingyang

AU - Fout, Alison R.

PY - 2016/9/14

Y1 - 2016/9/14

N2 - The synthesis of a cobalt dihydrogen CoI-(H2) complex prepared from a CoI-(N2) precursor supported by a monoanionic pincer bis(carbene) ligand, MesCCC (MesCCC = bis(mesityl-benzimidazol-2-ylidene)phenyl), is described. This species is capable of H2/D2 scrambling and hydrogenating alkenes at room temperature. Stoichiometric addition of HCl to the CoI-(N2) cleanly affords the CoIII hydridochloride complex, which, upon the addition of Cp2ZrHCl, evolves hydrogen gas and regenerates the CoI-(N2) complex. Furthermore, the catalytic olefin hydrogenation activity of the CoI species was studied by using multinuclear and parahydrogen (p-H2) induced polarization (PHIP) transfer NMR studies to elucidate catalytically relevant intermediates, as well as to establish the role of the CoI-(H2) in the CoI/CoIII redox cycle.

AB - The synthesis of a cobalt dihydrogen CoI-(H2) complex prepared from a CoI-(N2) precursor supported by a monoanionic pincer bis(carbene) ligand, MesCCC (MesCCC = bis(mesityl-benzimidazol-2-ylidene)phenyl), is described. This species is capable of H2/D2 scrambling and hydrogenating alkenes at room temperature. Stoichiometric addition of HCl to the CoI-(N2) cleanly affords the CoIII hydridochloride complex, which, upon the addition of Cp2ZrHCl, evolves hydrogen gas and regenerates the CoI-(N2) complex. Furthermore, the catalytic olefin hydrogenation activity of the CoI species was studied by using multinuclear and parahydrogen (p-H2) induced polarization (PHIP) transfer NMR studies to elucidate catalytically relevant intermediates, as well as to establish the role of the CoI-(H2) in the CoI/CoIII redox cycle.

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Well-Defined Cobalt(I) Dihydrogen Catalyst: Experimental Evidence for a Co(I)/Co(III) Redox Process in Olefin Hydrogenation

Abstract

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