TY - JOUR
T1 - Quinoline Pyridine(Imine) Iron Complexes as Catalysts for the 1,4-Hydrovinylation of 1,3-Dienes
AU - Duchemin, Coralie
AU - Liu, Amelia I.
AU - Kim, Junho
AU - Chirik, Paul J.
N1 - Publisher Copyright:
© 2023 American Chemical Society.
PY - 2023/11/13
Y1 - 2023/11/13
N2 - The synthesis, characterization, and stoichiometric reactivity of a series of quinoline pyridine(imine) (R(R’)Q(R”)PI) (R = 2,6-Me, 2,6-iPr or 2,4,6-Cy; R’ = H or Cl, R″ = H or tBu) iron dichloride complexes is described. Treatment of (QPI)FeCl2 with two equivalents of methyl lithium furnished two examples of the corresponding (QPI)FeCH3 complexes. The molecular structures were established by X-ray diffraction, and the electronic structures were studied by magnetometry, 57Fe Mössbauer spectroscopy, and DFT calculations. The combined data support overall S = 3/2 ground states that are best described as high spin iron(II) complexes engaged in antiferromagnetic coupling with a chelate radical anion, similar to related pyridine(diimine) and terpyridine iron alkyl complexes. Bimolecular reductive elimination of ethane in the presence of butadiene afforded an iron crotyl complex bearing a cyclometalated QPI ligand, formed upon ligand-to-ligand hydrogen transfer (LLHT) or stepwise oxidative addition/reduction elimination from a putative (QPI) iron butadiene intermediate. The cyclometalated QPI iron crotyl complex proved to be a competent catalyst for the hydrovinylation of butadiene with ethylene and produced high selectivity for the hexa-1,4-diene isomer. Deuterium labeling experiments established H/D scrambling between ethylene, butadiene and the QPI ligand, consistent with background transfer hydrogenation reactivity and catalyst decomposition observed during catalysis.
AB - The synthesis, characterization, and stoichiometric reactivity of a series of quinoline pyridine(imine) (R(R’)Q(R”)PI) (R = 2,6-Me, 2,6-iPr or 2,4,6-Cy; R’ = H or Cl, R″ = H or tBu) iron dichloride complexes is described. Treatment of (QPI)FeCl2 with two equivalents of methyl lithium furnished two examples of the corresponding (QPI)FeCH3 complexes. The molecular structures were established by X-ray diffraction, and the electronic structures were studied by magnetometry, 57Fe Mössbauer spectroscopy, and DFT calculations. The combined data support overall S = 3/2 ground states that are best described as high spin iron(II) complexes engaged in antiferromagnetic coupling with a chelate radical anion, similar to related pyridine(diimine) and terpyridine iron alkyl complexes. Bimolecular reductive elimination of ethane in the presence of butadiene afforded an iron crotyl complex bearing a cyclometalated QPI ligand, formed upon ligand-to-ligand hydrogen transfer (LLHT) or stepwise oxidative addition/reduction elimination from a putative (QPI) iron butadiene intermediate. The cyclometalated QPI iron crotyl complex proved to be a competent catalyst for the hydrovinylation of butadiene with ethylene and produced high selectivity for the hexa-1,4-diene isomer. Deuterium labeling experiments established H/D scrambling between ethylene, butadiene and the QPI ligand, consistent with background transfer hydrogenation reactivity and catalyst decomposition observed during catalysis.
UR - http://www.scopus.com/inward/record.url?scp=85177071188&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85177071188&partnerID=8YFLogxK
U2 - 10.1021/acs.organomet.3c00356
DO - 10.1021/acs.organomet.3c00356
M3 - Article
AN - SCOPUS:85177071188
SN - 0276-7333
VL - 42
SP - 3109
EP - 3119
JO - Organometallics
JF - Organometallics
IS - 21
ER -