Oxidative Addition of Dihydrogen, Boron Compounds, and Aryl Halides to a Cobalt(I) Cation Supported by a Strong-Field Pincer Ligand

Stephan M. Rummelt; Hongyu Zhong; Nadia G. Léonard; Scott P. Semproni; Paul J. Chirik

doi:10.1021/acs.organomet.8b00870

Oxidative Addition of Dihydrogen, Boron Compounds, and Aryl Halides to a Cobalt(I) Cation Supported by a Strong-Field Pincer Ligand

Stephan M. Rummelt, Hongyu Zhong, Nadia G. Léonard, Scott P. Semproni, Paul J. Chirik

Chemistry

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

29 Scopus citations

Abstract

Cationic cobalt(I) dinitrogen complexes with a strong-field tridentate pincer ligand were prepared, and the oxidative addition of polar and nonpolar bonds was studied. Addition of H ₂ to [( ^iPr PNP)Co(N ₂ )] ⁺ ( ^iPr PNP = 2,6-bis((diisopropylphosphaneyl)methyl)pyridine) in deuterated tetrahydrofuran (THF) resulted in rapid oxidative addition and formation of the cis-Co(III) dihydride complex, cis-[( ^iPr PNP)Co(H) ₂ L] ⁺ , where L = THF or N ₂ . The addition of H ₂ was reversible as evidenced by the dynamics observed by variable-temperature ¹ H NMR spectroscopy and the regeneration of [( ^iPr PNP)Co(N ₂ )] ⁺ upon exposure to dinitrogen. In contrast, addition of HBPin (Pin = pinacolato), B ₂ Pin ₂ , and aryl halides resulted in the formation of net one-electron oxidation products: cationic Co(II)-boryl and Co(II)-halide/aryl complexes, respectively. All products were structurally characterized by X-ray crystallography, and the electronic structures were determined by a combination of magnetic moment measurements, electron paramagnetic resonance spectroscopy, and density functional theory calculations. Monitoring the addition of HBPin to [( ^iPr PNP)Co(N ₂ )] ⁺ provided evidence for a transient Co(III) oxidative addition product that likely undergoes comproportionation with the cobalt(I) starting material to generate the observed Co(II) products.

Original language	English (US)
Pages (from-to)	1081-1090
Number of pages	10
Journal	Organometallics
Volume	38
Issue number	5
DOIs	https://doi.org/10.1021/acs.organomet.8b00870
State	Published - Mar 11 2019

All Science Journal Classification (ASJC) codes

Inorganic Chemistry
Physical and Theoretical Chemistry
Organic Chemistry

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title = "Oxidative Addition of Dihydrogen, Boron Compounds, and Aryl Halides to a Cobalt(I) Cation Supported by a Strong-Field Pincer Ligand",

abstract = " Cationic cobalt(I) dinitrogen complexes with a strong-field tridentate pincer ligand were prepared, and the oxidative addition of polar and nonpolar bonds was studied. Addition of H 2 to [( iPr PNP)Co(N 2 )] + ( iPr PNP = 2,6-bis((diisopropylphosphaneyl)methyl)pyridine) in deuterated tetrahydrofuran (THF) resulted in rapid oxidative addition and formation of the cis-Co(III) dihydride complex, cis-[( iPr PNP)Co(H) 2 L] + , where L = THF or N 2 . The addition of H 2 was reversible as evidenced by the dynamics observed by variable-temperature 1 H NMR spectroscopy and the regeneration of [( iPr PNP)Co(N 2 )] + upon exposure to dinitrogen. In contrast, addition of HBPin (Pin = pinacolato), B 2 Pin 2 , and aryl halides resulted in the formation of net one-electron oxidation products: cationic Co(II)-boryl and Co(II)-halide/aryl complexes, respectively. All products were structurally characterized by X-ray crystallography, and the electronic structures were determined by a combination of magnetic moment measurements, electron paramagnetic resonance spectroscopy, and density functional theory calculations. Monitoring the addition of HBPin to [( iPr PNP)Co(N 2 )] + provided evidence for a transient Co(III) oxidative addition product that likely undergoes comproportionation with the cobalt(I) starting material to generate the observed Co(II) products.",

author = "Rummelt, {Stephan M.} and Hongyu Zhong and L{\'e}onard, {Nadia G.} and Semproni, {Scott P.} and Chirik, {Paul J.}",

note = "Publisher Copyright: {\textcopyright} 2019 American Chemical Society.",

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doi = "10.1021/acs.organomet.8b00870",

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T1 - Oxidative Addition of Dihydrogen, Boron Compounds, and Aryl Halides to a Cobalt(I) Cation Supported by a Strong-Field Pincer Ligand

AU - Rummelt, Stephan M.

AU - Zhong, Hongyu

AU - Léonard, Nadia G.

AU - Semproni, Scott P.

AU - Chirik, Paul J.

PY - 2019/3/11

Y1 - 2019/3/11

N2 - Cationic cobalt(I) dinitrogen complexes with a strong-field tridentate pincer ligand were prepared, and the oxidative addition of polar and nonpolar bonds was studied. Addition of H 2 to [( iPr PNP)Co(N 2 )] + ( iPr PNP = 2,6-bis((diisopropylphosphaneyl)methyl)pyridine) in deuterated tetrahydrofuran (THF) resulted in rapid oxidative addition and formation of the cis-Co(III) dihydride complex, cis-[( iPr PNP)Co(H) 2 L] + , where L = THF or N 2 . The addition of H 2 was reversible as evidenced by the dynamics observed by variable-temperature 1 H NMR spectroscopy and the regeneration of [( iPr PNP)Co(N 2 )] + upon exposure to dinitrogen. In contrast, addition of HBPin (Pin = pinacolato), B 2 Pin 2 , and aryl halides resulted in the formation of net one-electron oxidation products: cationic Co(II)-boryl and Co(II)-halide/aryl complexes, respectively. All products were structurally characterized by X-ray crystallography, and the electronic structures were determined by a combination of magnetic moment measurements, electron paramagnetic resonance spectroscopy, and density functional theory calculations. Monitoring the addition of HBPin to [( iPr PNP)Co(N 2 )] + provided evidence for a transient Co(III) oxidative addition product that likely undergoes comproportionation with the cobalt(I) starting material to generate the observed Co(II) products.

AB - Cationic cobalt(I) dinitrogen complexes with a strong-field tridentate pincer ligand were prepared, and the oxidative addition of polar and nonpolar bonds was studied. Addition of H 2 to [( iPr PNP)Co(N 2 )] + ( iPr PNP = 2,6-bis((diisopropylphosphaneyl)methyl)pyridine) in deuterated tetrahydrofuran (THF) resulted in rapid oxidative addition and formation of the cis-Co(III) dihydride complex, cis-[( iPr PNP)Co(H) 2 L] + , where L = THF or N 2 . The addition of H 2 was reversible as evidenced by the dynamics observed by variable-temperature 1 H NMR spectroscopy and the regeneration of [( iPr PNP)Co(N 2 )] + upon exposure to dinitrogen. In contrast, addition of HBPin (Pin = pinacolato), B 2 Pin 2 , and aryl halides resulted in the formation of net one-electron oxidation products: cationic Co(II)-boryl and Co(II)-halide/aryl complexes, respectively. All products were structurally characterized by X-ray crystallography, and the electronic structures were determined by a combination of magnetic moment measurements, electron paramagnetic resonance spectroscopy, and density functional theory calculations. Monitoring the addition of HBPin to [( iPr PNP)Co(N 2 )] + provided evidence for a transient Co(III) oxidative addition product that likely undergoes comproportionation with the cobalt(I) starting material to generate the observed Co(II) products.

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U2 - 10.1021/acs.organomet.8b00870

DO - 10.1021/acs.organomet.8b00870

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SN - 0276-7333

VL - 38

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EP - 1090

JO - Organometallics

JF - Organometallics

IS - 5

ER -

Oxidative Addition of Dihydrogen, Boron Compounds, and Aryl Halides to a Cobalt(I) Cation Supported by a Strong-Field Pincer Ligand

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