Arene coordination in bis(imino)pyridine iron complexes: Identification of catalyst deactivation pathways in iron-catalyzed hydrogenation and hydrosilation

Andrew M. Archer; Marco W. Bouwkamp; Maria Patricia Cortez; Emil Lobkovsky; Paul J. Chirik

doi:10.1021/om060441c

Arene coordination in bis(imino)pyridine iron complexes: Identification of catalyst deactivation pathways in iron-catalyzed hydrogenation and hydrosilation

Andrew M. Archer, Marco W. Bouwkamp, Maria Patricia Cortez, Emil Lobkovsky, Paul J. Chirik

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Abstract

The phenyl-substituted bis(imino)pyridine iron bis(dinitrogen) complex ( ⁱPrPhPDI)Fe(N ₂) ₂ ( ⁱPrPhPDI = 2,6-(2,6- ⁱPr ₂-C ₆H ₃N=CPh) ₂C ₅H ₃N) was prepared by sodium amalgam reduction of the corresponding ferrous dichloride precursor under 4 atm of dinitrogen. Comparison of the infrared stretching frequencies of the bis(dinitrogen), mono(dinitrogen), and related dicarbonyl derivatives to those of the corresponding bis(imino)pyridine iron compounds bearing the methyl-substituted ligand, ( ⁱPrPDI)Fe(L) _n ( ⁱPrPDI = 2,6-(2,6- ⁱPr ₂-C ₆H ₃N=CMe) ₂C ₅H ₃N; L = CO, n = 2; L = N ₂, n = 1, 2), established a more electrophilic iron center for the phenyl-substituted cases. Comparing the productivity of ( ⁱPrPhPDI) Fe(N ₂) ₂ to ( ⁱPrPDI)Fe(N ₂) ₂ in the catalytic hydrogenation and hydrosilation of 1-hexene demonstrated higher turnover frequencies for ( ⁱPrPhPDI)Fe(N ₂) ₂. For more hindered substrates such as cyclohexene and (+)-(R)-limonene, the opposite trend was observed, where the methyl-substituted precursor, ( ⁱPrPDI)Fe(N ₂) ₂, produced more rapid conversion. The difference in catalytic performance resulted from competitive, irreversible formation of η ⁶-aryl and -phenyl compounds with the phenyl-substituted complex. Addition of coordinating solvents such as cyclohexene or THF resulted in exclusive formation of the η ⁶- phenyl derivative. When alkoxide substituents are introduced in the bis(imino)pyridine ligand backbone, the formation of η ⁶-aryl compounds was exclusive, as alkali metal reduction of ( ⁱPrROPDI) FeBr ₂ ( ⁱPrROPDI = 2,6-(2,6- ⁱPr ₂-C ₆H ₃N=C(OR)) ₂C ₅H ₃N, R = Me, Et) yielded only the catalytically inactive η ⁶-aryl species.

Original language	English (US)
Pages (from-to)	4269-4278
Number of pages	10
Journal	Organometallics
Volume	25
Issue number	18
DOIs	https://doi.org/10.1021/om060441c
State	Published - Aug 28 2006
Externally published	Yes

All Science Journal Classification (ASJC) codes

Physical and Theoretical Chemistry
Organic Chemistry
Inorganic Chemistry

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@article{a8e00ca88a4849f99767aa0140575280,

title = "Arene coordination in bis(imino)pyridine iron complexes: Identification of catalyst deactivation pathways in iron-catalyzed hydrogenation and hydrosilation",

abstract = "The phenyl-substituted bis(imino)pyridine iron bis(dinitrogen) complex ( iPrPhPDI)Fe(N 2) 2 ( iPrPhPDI = 2,6-(2,6- iPr 2-C 6H 3N=CPh) 2C 5H 3N) was prepared by sodium amalgam reduction of the corresponding ferrous dichloride precursor under 4 atm of dinitrogen. Comparison of the infrared stretching frequencies of the bis(dinitrogen), mono(dinitrogen), and related dicarbonyl derivatives to those of the corresponding bis(imino)pyridine iron compounds bearing the methyl-substituted ligand, ( iPrPDI)Fe(L) n ( iPrPDI = 2,6-(2,6- iPr 2-C 6H 3N=CMe) 2C 5H 3N; L = CO, n = 2; L = N 2, n = 1, 2), established a more electrophilic iron center for the phenyl-substituted cases. Comparing the productivity of ( iPrPhPDI) Fe(N 2) 2 to ( iPrPDI)Fe(N 2) 2 in the catalytic hydrogenation and hydrosilation of 1-hexene demonstrated higher turnover frequencies for ( iPrPhPDI)Fe(N 2) 2. For more hindered substrates such as cyclohexene and (+)-(R)-limonene, the opposite trend was observed, where the methyl-substituted precursor, ( iPrPDI)Fe(N 2) 2, produced more rapid conversion. The difference in catalytic performance resulted from competitive, irreversible formation of η 6-aryl and -phenyl compounds with the phenyl-substituted complex. Addition of coordinating solvents such as cyclohexene or THF resulted in exclusive formation of the η 6- phenyl derivative. When alkoxide substituents are introduced in the bis(imino)pyridine ligand backbone, the formation of η 6-aryl compounds was exclusive, as alkali metal reduction of ( iPrROPDI) FeBr 2 ( iPrROPDI = 2,6-(2,6- iPr 2-C 6H 3N=C(OR)) 2C 5H 3N, R = Me, Et) yielded only the catalytically inactive η 6-aryl species.",

author = "Archer, \{Andrew M.\} and Bouwkamp, \{Marco W.\} and Cortez, \{Maria Patricia\} and Emil Lobkovsky and Chirik, \{Paul J.\}",

year = "2006",

month = aug,

day = "28",

doi = "10.1021/om060441c",

language = "English (US)",

volume = "25",

pages = "4269--4278",

journal = "Organometallics",

issn = "0276-7333",

publisher = "American Chemical Society",

number = "18",

}

TY - JOUR

T1 - Arene coordination in bis(imino)pyridine iron complexes

T2 - Identification of catalyst deactivation pathways in iron-catalyzed hydrogenation and hydrosilation

AU - Archer, Andrew M.

AU - Bouwkamp, Marco W.

AU - Cortez, Maria Patricia

AU - Lobkovsky, Emil

AU - Chirik, Paul J.

PY - 2006/8/28

Y1 - 2006/8/28

N2 - The phenyl-substituted bis(imino)pyridine iron bis(dinitrogen) complex ( iPrPhPDI)Fe(N 2) 2 ( iPrPhPDI = 2,6-(2,6- iPr 2-C 6H 3N=CPh) 2C 5H 3N) was prepared by sodium amalgam reduction of the corresponding ferrous dichloride precursor under 4 atm of dinitrogen. Comparison of the infrared stretching frequencies of the bis(dinitrogen), mono(dinitrogen), and related dicarbonyl derivatives to those of the corresponding bis(imino)pyridine iron compounds bearing the methyl-substituted ligand, ( iPrPDI)Fe(L) n ( iPrPDI = 2,6-(2,6- iPr 2-C 6H 3N=CMe) 2C 5H 3N; L = CO, n = 2; L = N 2, n = 1, 2), established a more electrophilic iron center for the phenyl-substituted cases. Comparing the productivity of ( iPrPhPDI) Fe(N 2) 2 to ( iPrPDI)Fe(N 2) 2 in the catalytic hydrogenation and hydrosilation of 1-hexene demonstrated higher turnover frequencies for ( iPrPhPDI)Fe(N 2) 2. For more hindered substrates such as cyclohexene and (+)-(R)-limonene, the opposite trend was observed, where the methyl-substituted precursor, ( iPrPDI)Fe(N 2) 2, produced more rapid conversion. The difference in catalytic performance resulted from competitive, irreversible formation of η 6-aryl and -phenyl compounds with the phenyl-substituted complex. Addition of coordinating solvents such as cyclohexene or THF resulted in exclusive formation of the η 6- phenyl derivative. When alkoxide substituents are introduced in the bis(imino)pyridine ligand backbone, the formation of η 6-aryl compounds was exclusive, as alkali metal reduction of ( iPrROPDI) FeBr 2 ( iPrROPDI = 2,6-(2,6- iPr 2-C 6H 3N=C(OR)) 2C 5H 3N, R = Me, Et) yielded only the catalytically inactive η 6-aryl species.

AB - The phenyl-substituted bis(imino)pyridine iron bis(dinitrogen) complex ( iPrPhPDI)Fe(N 2) 2 ( iPrPhPDI = 2,6-(2,6- iPr 2-C 6H 3N=CPh) 2C 5H 3N) was prepared by sodium amalgam reduction of the corresponding ferrous dichloride precursor under 4 atm of dinitrogen. Comparison of the infrared stretching frequencies of the bis(dinitrogen), mono(dinitrogen), and related dicarbonyl derivatives to those of the corresponding bis(imino)pyridine iron compounds bearing the methyl-substituted ligand, ( iPrPDI)Fe(L) n ( iPrPDI = 2,6-(2,6- iPr 2-C 6H 3N=CMe) 2C 5H 3N; L = CO, n = 2; L = N 2, n = 1, 2), established a more electrophilic iron center for the phenyl-substituted cases. Comparing the productivity of ( iPrPhPDI) Fe(N 2) 2 to ( iPrPDI)Fe(N 2) 2 in the catalytic hydrogenation and hydrosilation of 1-hexene demonstrated higher turnover frequencies for ( iPrPhPDI)Fe(N 2) 2. For more hindered substrates such as cyclohexene and (+)-(R)-limonene, the opposite trend was observed, where the methyl-substituted precursor, ( iPrPDI)Fe(N 2) 2, produced more rapid conversion. The difference in catalytic performance resulted from competitive, irreversible formation of η 6-aryl and -phenyl compounds with the phenyl-substituted complex. Addition of coordinating solvents such as cyclohexene or THF resulted in exclusive formation of the η 6- phenyl derivative. When alkoxide substituents are introduced in the bis(imino)pyridine ligand backbone, the formation of η 6-aryl compounds was exclusive, as alkali metal reduction of ( iPrROPDI) FeBr 2 ( iPrROPDI = 2,6-(2,6- iPr 2-C 6H 3N=C(OR)) 2C 5H 3N, R = Me, Et) yielded only the catalytically inactive η 6-aryl species.

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U2 - 10.1021/om060441c

DO - 10.1021/om060441c

M3 - Article

AN - SCOPUS:33748569455

SN - 0276-7333

VL - 25

SP - 4269

EP - 4278

JO - Organometallics

JF - Organometallics

IS - 18

ER -

Arene coordination in bis(imino)pyridine iron complexes: Identification of catalyst deactivation pathways in iron-catalyzed hydrogenation and hydrosilation

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