Cationic Cobalt(II) Bisphosphine Hydroformylation Catalysis: In Situ Spectroscopic and Reaction Studies
[HCo(CO) x (bisphosphine)](BF4), x = 1–3, is a highly active hydroformylation catalyst system, especially for internal branched alkenes. In situ infrared spectroscopy (IR), electron paramagnetic resonance (EPR), and nuclear magnetic resonance studies support the proposed catalyst formulation. IR s...
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Published in | Journal of the American Chemical Society Vol. 145; no. 36; pp. 19715 - 19726 |
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Main Authors | , , , , |
Format | Journal Article |
Language | English |
Published |
United States
American Chemical Society
13.09.2023
American Chemical Society (ACS) |
Subjects | |
Online Access | Get full text |
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Summary: | [HCo(CO) x (bisphosphine)](BF4), x = 1–3, is a highly active hydroformylation catalyst system, especially for internal branched alkenes. In situ infrared spectroscopy (IR), electron paramagnetic resonance (EPR), and nuclear magnetic resonance studies support the proposed catalyst formulation. IR studies reveal the formation of a dicationic Co(I) paramagnetic CO-bridged dimer, [Co2(μ-CO)2(CO)(bisphosphine)2]2+, at lower temperatures formed from the reaction of two catalyst complexes via the elimination of H2. DFT studies indicate a dimer structure with square-pyramidal and tetrahedral cobalt centers. This monomer–dimer equilibrium is analogous to that seen for HCo(CO)4, reacting to eliminate H2 and form Co2(CO)8. EPR studies on the catalyst show a high-spin (S = 3/2) Co(II) complex. Reaction studies are presented that support the cationic Co(II) bisphosphine catalyst as the catalyst species present in this system and minimize the possible role of neutral Co(I) species, HCo(CO)4 or HCo(CO)3(phosphine), as catalysts. |
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Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 SC0020119; CHE-01-11117 National Science Foundation (NSF) USDOE Office of Science (SC), Basic Energy Sciences (BES). Chemical Sciences, Geosciences & Biosciences Division (CSGB) |
ISSN: | 0002-7863 1520-5126 |
DOI: | 10.1021/jacs.3c04866 |