Abstract
The complex [Co(H3L)](ClO4)3·H 2O (1), where H3L {tris[2-(4-imidazoylmethylideneamino) ethyl]amine} is a tripodal ligand obtained by condensation of tris(2-aminoethyl)amine and 4-formylimidazole in a 1:3 molar ratio, was synthesized and optically resolved by fractional crystallization of the diastereomeric salt with [Sb2{(R,R)-tart}2]2- [(R,R)-tart = (2R,3R)-tartrate(4-) ion]. From the less soluble part, Λ-[Co(H2L)][Sb2-{(R,R)-tart}2] ·4H2O (2) was isolated. Starting from 2, two optically active complexes, Λ-[Co(H3L)](ClO4)3·1. 5H2O (Λ-1) and Λ-[Co(L)] (Λ-3), were obtained. The crystal structures of these complexes are compared with those of the racemic structures. Λ-1 shows an unusually strong circular dichroism (λ = 488 nm, Δε = -7.74 M-1 cm-1) in the first d-d absorption band region. The effects of deprotonation-reprotonation of the uncoordinated imidazole NH groups of Λ-[Co(H3L)]3+ on the UV/Vis and CD spectra and on the cyclic voltammograms were studied in methanol. Although the deprotonation-reprotonation reactions are reversible, the redox couple for the completely deprotonated species [CoIII/II(L)] 0/- is not observed.
| Original language | English |
|---|---|
| Pages (from-to) | 1258-1267 |
| Number of pages | 10 |
| Journal | European Journal of Inorganic Chemistry |
| Issue number | 8 |
| DOIs | |
| Publication status | Published - Mar 2008 |
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Keywords
- Chiral resolution
- Cobalt
- Crystal structure
- N ligands
- Schiff bases
- Tripodal ligands
ASJC Scopus subject areas
- Inorganic Chemistry
Cite this
Cobalt(III) complexes of a tripodal ligand containing three imidazole groups : Properties and structures of racemic and optically active species. / Nakamura, Hirofumi; Fujii, Megumi; Sunatsuki, Yukinari; Kojima, Masaaki; Matsumoto, Naohide.
In: European Journal of Inorganic Chemistry, No. 8, 03.2008, p. 1258-1267.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Cobalt(III) complexes of a tripodal ligand containing three imidazole groups
T2 - Properties and structures of racemic and optically active species
AU - Nakamura, Hirofumi
AU - Fujii, Megumi
AU - Sunatsuki, Yukinari
AU - Kojima, Masaaki
AU - Matsumoto, Naohide
PY - 2008/3
Y1 - 2008/3
N2 - The complex [Co(H3L)](ClO4)3·H 2O (1), where H3L {tris[2-(4-imidazoylmethylideneamino) ethyl]amine} is a tripodal ligand obtained by condensation of tris(2-aminoethyl)amine and 4-formylimidazole in a 1:3 molar ratio, was synthesized and optically resolved by fractional crystallization of the diastereomeric salt with [Sb2{(R,R)-tart}2]2- [(R,R)-tart = (2R,3R)-tartrate(4-) ion]. From the less soluble part, Λ-[Co(H2L)][Sb2-{(R,R)-tart}2] ·4H2O (2) was isolated. Starting from 2, two optically active complexes, Λ-[Co(H3L)](ClO4)3·1. 5H2O (Λ-1) and Λ-[Co(L)] (Λ-3), were obtained. The crystal structures of these complexes are compared with those of the racemic structures. Λ-1 shows an unusually strong circular dichroism (λ = 488 nm, Δε = -7.74 M-1 cm-1) in the first d-d absorption band region. The effects of deprotonation-reprotonation of the uncoordinated imidazole NH groups of Λ-[Co(H3L)]3+ on the UV/Vis and CD spectra and on the cyclic voltammograms were studied in methanol. Although the deprotonation-reprotonation reactions are reversible, the redox couple for the completely deprotonated species [CoIII/II(L)] 0/- is not observed.
AB - The complex [Co(H3L)](ClO4)3·H 2O (1), where H3L {tris[2-(4-imidazoylmethylideneamino) ethyl]amine} is a tripodal ligand obtained by condensation of tris(2-aminoethyl)amine and 4-formylimidazole in a 1:3 molar ratio, was synthesized and optically resolved by fractional crystallization of the diastereomeric salt with [Sb2{(R,R)-tart}2]2- [(R,R)-tart = (2R,3R)-tartrate(4-) ion]. From the less soluble part, Λ-[Co(H2L)][Sb2-{(R,R)-tart}2] ·4H2O (2) was isolated. Starting from 2, two optically active complexes, Λ-[Co(H3L)](ClO4)3·1. 5H2O (Λ-1) and Λ-[Co(L)] (Λ-3), were obtained. The crystal structures of these complexes are compared with those of the racemic structures. Λ-1 shows an unusually strong circular dichroism (λ = 488 nm, Δε = -7.74 M-1 cm-1) in the first d-d absorption band region. The effects of deprotonation-reprotonation of the uncoordinated imidazole NH groups of Λ-[Co(H3L)]3+ on the UV/Vis and CD spectra and on the cyclic voltammograms were studied in methanol. Although the deprotonation-reprotonation reactions are reversible, the redox couple for the completely deprotonated species [CoIII/II(L)] 0/- is not observed.
KW - Chiral resolution
KW - Cobalt
KW - Crystal structure
KW - N ligands
KW - Schiff bases
KW - Tripodal ligands
UR - http://www.scopus.com/inward/record.url?scp=46749137928&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=46749137928&partnerID=8YFLogxK
U2 - 10.1002/ejic.200700950
DO - 10.1002/ejic.200700950
M3 - Article
AN - SCOPUS:46749137928
SP - 1258
EP - 1267
JO - Chemische Berichte
JF - Chemische Berichte
SN - 0009-2940
IS - 8
ER -