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Title: Exploring the Alcohol Stability of Bis(phosphine) Cobalt Dialkyl Precatalysts in Asymmetric Alkene Hydrogenation

Abstract

Here, cobalt complexes bearing enantiopure, bidentate bis(phosphine) ligands exhibit extraordinary activity and stereoselectivity for the hydrogenation of enamides. Optimal performance was observed in polar protic solvents such as methanol, an industrially preferred green solvent but a medium that is often a poison for reduced Earth abundant metals. The interaction of the low spin cobalt(II) dialkyl complex, ( R,R)-( iPr-DuPhos)Co(CH 2SiMe 3) 2 with alcohols including: 4-methoxyphenol, pinacol, and CH 3OH was studied. With the alcohols lacking beta-hydrogens, cobalt bis(alkoxide) complexes were isolated and structurally characterized. With methanol, protonolysis of the alkyl ligands was again observed followed by dehydrogenation of the alcohol and [( R,R)-( iPr-DuPhos)Co] 2(mu-CO) 2 was isolated. Both solid-state and solution EXAFS studies were conducted to establish the spectroscopic signatures of bis(phosphine)cobalt(II) and cobalt(0) complexes relevant to catalytic hydrogenation and also to probe the role of phosphine dissociation in methanol.

Authors:
ORCiD logo [1];  [1]; ORCiD logo [2];  [2];  [2]; ORCiD logo [2]; ORCiD logo [1]
  1. Princeton Univ., Princeton, NJ (United States)
  2. Argonne National Lab. (ANL), Lemont, IL (United States)
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1481713
Alternate Identifier(s):
OSTI ID: 1493760
Grant/Contract Number:  
AC02-06CH11357
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Organometallics
Additional Journal Information:
Journal Volume: 38; Journal Issue: 1; Journal ID: ISSN 0276-7333
Publisher:
American Chemical Society
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY

Citation Formats

Zhong, Hongyu, Friedfeld, Max R., Camacho-Bunquin, Jeffrey, Sohn, Hyuntae, Yang, Ce, Delferro, Massimiliano, and Chirik, Paul J. Exploring the Alcohol Stability of Bis(phosphine) Cobalt Dialkyl Precatalysts in Asymmetric Alkene Hydrogenation. United States: N. p., 2018. Web. doi:10.1021/acs.organomet.8b00516.
Zhong, Hongyu, Friedfeld, Max R., Camacho-Bunquin, Jeffrey, Sohn, Hyuntae, Yang, Ce, Delferro, Massimiliano, & Chirik, Paul J. Exploring the Alcohol Stability of Bis(phosphine) Cobalt Dialkyl Precatalysts in Asymmetric Alkene Hydrogenation. United States. doi:10.1021/acs.organomet.8b00516.
Zhong, Hongyu, Friedfeld, Max R., Camacho-Bunquin, Jeffrey, Sohn, Hyuntae, Yang, Ce, Delferro, Massimiliano, and Chirik, Paul J. Mon . "Exploring the Alcohol Stability of Bis(phosphine) Cobalt Dialkyl Precatalysts in Asymmetric Alkene Hydrogenation". United States. doi:10.1021/acs.organomet.8b00516.
@article{osti_1481713,
title = {Exploring the Alcohol Stability of Bis(phosphine) Cobalt Dialkyl Precatalysts in Asymmetric Alkene Hydrogenation},
author = {Zhong, Hongyu and Friedfeld, Max R. and Camacho-Bunquin, Jeffrey and Sohn, Hyuntae and Yang, Ce and Delferro, Massimiliano and Chirik, Paul J.},
abstractNote = {Here, cobalt complexes bearing enantiopure, bidentate bis(phosphine) ligands exhibit extraordinary activity and stereoselectivity for the hydrogenation of enamides. Optimal performance was observed in polar protic solvents such as methanol, an industrially preferred green solvent but a medium that is often a poison for reduced Earth abundant metals. The interaction of the low spin cobalt(II) dialkyl complex, (R,R)-(iPr-DuPhos)Co(CH2SiMe3)2 with alcohols including: 4-methoxyphenol, pinacol, and CH3OH was studied. With the alcohols lacking beta-hydrogens, cobalt bis(alkoxide) complexes were isolated and structurally characterized. With methanol, protonolysis of the alkyl ligands was again observed followed by dehydrogenation of the alcohol and [(R,R)-(iPr-DuPhos)Co]2(mu-CO)2 was isolated. Both solid-state and solution EXAFS studies were conducted to establish the spectroscopic signatures of bis(phosphine)cobalt(II) and cobalt(0) complexes relevant to catalytic hydrogenation and also to probe the role of phosphine dissociation in methanol.},
doi = {10.1021/acs.organomet.8b00516},
journal = {Organometallics},
issn = {0276-7333},
number = 1,
volume = 38,
place = {United States},
year = {2018},
month = {11}
}

Journal Article:
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