Cobalt and iron complexes of chiral C1- and C2-terpyridines: Synthesis, characterization and use in catalytic asymmetric cyclopropanation of styrenes

Chi Tung Yeung; Kiu Chor Sham; Wing Sze Lee; Wing Tak Wong; Wai Yeung WONG; Hoi Lun Kwong

doi:10.1016/j.ica.2009.02.034

Cobalt and iron complexes of chiral C₁- and C₂-terpyridines: Synthesis, characterization and use in catalytic asymmetric cyclopropanation of styrenes

Chi Tung Yeung, Kiu Chor Sham, Wing Sze Lee, Wing Tak Wong, Wai Yeung WONG, Hoi Lun Kwong^*

^*Corresponding author for this work

Department of Chemistry

Research output: Contribution to journal › Journal article › peer-review

32 Citations (Scopus)

Abstract

Optically pure C₁- and C₂-terpyridine ligands (L) form cobalt(II) and iron(II) complexes of formula [Co(L)Cl₂] and [Fe(L)Cl₂], respectively, and Iron(III) complexes of formulas [Fe(L)Cl₃]. Structures of three new chiral cobalt(II) and one iron(III) complexes were analysed using X-ray crystal structure analysis. These complexes were shown to be precursor of efficient catalyst for cyclopropanation. Reaction with AgOTf converted the complex to active catalyst, which gave enantioselectivities of up to 76% ee for the trans-isomers and 83% ee for the cis-isomers of styrene cyclopropanes with ethyl diazoacetate. Hammett studies showed the active species for both cobalt and iron complexes to have a non-linear relationship to σ_p constant.

Original language	English
Pages (from-to)	3267-3273
Number of pages	7
Journal	Inorganica Chimica Acta
Volume	362
Issue number	9
DOIs	https://doi.org/10.1016/j.ica.2009.02.034
Publication status	Published - 1 Jul 2009

Scopus Subject Areas

Physical and Theoretical Chemistry
Inorganic Chemistry
Materials Chemistry

User-Defined Keywords

Asymmetric catalysis
Chiral terpyridine
Cobalt
Cyclopropanation
Iron

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10.1016/j.ica.2009.02.034

Cite this

@article{d6fd8318541c47eebec2f0c576bf4fb1,

title = "Cobalt and iron complexes of chiral C1- and C2-terpyridines: Synthesis, characterization and use in catalytic asymmetric cyclopropanation of styrenes",

abstract = "Optically pure C1- and C2-terpyridine ligands (L) form cobalt(II) and iron(II) complexes of formula [Co(L)Cl2] and [Fe(L)Cl2], respectively, and Iron(III) complexes of formulas [Fe(L)Cl3]. Structures of three new chiral cobalt(II) and one iron(III) complexes were analysed using X-ray crystal structure analysis. These complexes were shown to be precursor of efficient catalyst for cyclopropanation. Reaction with AgOTf converted the complex to active catalyst, which gave enantioselectivities of up to 76% ee for the trans-isomers and 83% ee for the cis-isomers of styrene cyclopropanes with ethyl diazoacetate. Hammett studies showed the active species for both cobalt and iron complexes to have a non-linear relationship to σp constant.",

keywords = "Asymmetric catalysis, Chiral terpyridine, Cobalt, Cyclopropanation, Iron",

author = "Yeung, {Chi Tung} and Sham, {Kiu Chor} and Lee, {Wing Sze} and Wong, {Wing Tak} and WONG, {Wai Yeung} and Kwong, {Hoi Lun}",

note = "Funding Information: Financial support for this research from the City University of Hong Kong SRG Grants (CityU 7002000 and 7002223) are gratefully acknowledged. ",

year = "2009",

month = jul,

day = "1",

doi = "10.1016/j.ica.2009.02.034",

language = "English",

volume = "362",

pages = "3267--3273",

journal = "Inorganica Chimica Acta",

issn = "0020-1693",

publisher = "Elsevier BV",

number = "9",

}

TY - JOUR

T1 - Cobalt and iron complexes of chiral C1- and C2-terpyridines

T2 - Synthesis, characterization and use in catalytic asymmetric cyclopropanation of styrenes

AU - Yeung, Chi Tung

AU - Sham, Kiu Chor

AU - Lee, Wing Sze

AU - Wong, Wing Tak

AU - WONG, Wai Yeung

AU - Kwong, Hoi Lun

N1 - Funding Information: Financial support for this research from the City University of Hong Kong SRG Grants (CityU 7002000 and 7002223) are gratefully acknowledged.

PY - 2009/7/1

Y1 - 2009/7/1

N2 - Optically pure C1- and C2-terpyridine ligands (L) form cobalt(II) and iron(II) complexes of formula [Co(L)Cl2] and [Fe(L)Cl2], respectively, and Iron(III) complexes of formulas [Fe(L)Cl3]. Structures of three new chiral cobalt(II) and one iron(III) complexes were analysed using X-ray crystal structure analysis. These complexes were shown to be precursor of efficient catalyst for cyclopropanation. Reaction with AgOTf converted the complex to active catalyst, which gave enantioselectivities of up to 76% ee for the trans-isomers and 83% ee for the cis-isomers of styrene cyclopropanes with ethyl diazoacetate. Hammett studies showed the active species for both cobalt and iron complexes to have a non-linear relationship to σp constant.

AB - Optically pure C1- and C2-terpyridine ligands (L) form cobalt(II) and iron(II) complexes of formula [Co(L)Cl2] and [Fe(L)Cl2], respectively, and Iron(III) complexes of formulas [Fe(L)Cl3]. Structures of three new chiral cobalt(II) and one iron(III) complexes were analysed using X-ray crystal structure analysis. These complexes were shown to be precursor of efficient catalyst for cyclopropanation. Reaction with AgOTf converted the complex to active catalyst, which gave enantioselectivities of up to 76% ee for the trans-isomers and 83% ee for the cis-isomers of styrene cyclopropanes with ethyl diazoacetate. Hammett studies showed the active species for both cobalt and iron complexes to have a non-linear relationship to σp constant.

KW - Asymmetric catalysis

KW - Chiral terpyridine

KW - Cobalt

KW - Cyclopropanation

KW - Iron

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DO - 10.1016/j.ica.2009.02.034

M3 - Journal article

AN - SCOPUS:67349117789

SN - 0020-1693

VL - 362

SP - 3267

EP - 3273

JO - Inorganica Chimica Acta

JF - Inorganica Chimica Acta

IS - 9

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