• Journal of the Korean Chemical Society
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• v.34 no.2
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• pp.159-164
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• 1990

Absolute configuration of optically active [Co(EDDS)]- (EDDS = ethylenediaminedisuccinate) complex was determined as Λ-form by octant rule and spectroscopic data, and the stereoselective ionic association of Λ-[Co(EDDS)]- and racemic-$[Co(en)^3]_{3+}$ occurs preferrentially between Λ$-[Co(EDDS)]-$ and Δ$-[Co(en)3]3+$. The stereoselective electron-transfer reaction between Λ-[Co(EDDS)]- and racemic-$[Co(en)_3]^{2+}$ has produced 14% e.e (e.e = enantiomeric excess) of Δ$[Co(en)_3]^{3+}$ through the stereoselective ion pairing.

• Journal of the Korean Chemical Society
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• v.34 no.2
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• pp.211-214
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• 1990

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2018.11a
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• pp.275-276
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• 2018

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2018.11a
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• pp.273-274
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• 2018

• Journal of the Korean Chemical Society
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• v.39 no.4
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• pp.275-280
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• 1995

The electron transfer reactions between cis-[Co(en)2(NO2)2]+ and rac-[Co(Y)]2-(Y=EDTA, PDTA, CyDTA) have been investigated in the presence of hydrogen ion. From the kinetic data, it has been found that electron transfer reactions between cis-[Co(en)2(NO2)2]+ and rac-[Co(Y)]2- proceed via inner-sphere pathway by catalysis of hydogen ion. The stereoselectivity in the electron transfer reactions between optically active △-cis-[Co(en)2(NO2)2]+ and rac-[Co(Y)]2- produced 6.0, 2.9, 3.0% e.e.(e.e.=enantiomeric excess) of △-[Co(EDTA)]-, △-[Co(PDTA)]- and △-[Co(CyDTA)]-, respectively. Based upon this observation, it seems that △-cis-[Co(en)2(NO2)2]+ is associated with rac-[Co(Y)]2- at first, and followed by the electron transfer reaction. Therefore, it was suggested that stereoselective electron transfer reaction between △-cis-[Co(en)2(NO2)2]+ and rac-[Co(Y)]2- proceed through both inner-sphere by the proton catalysis and outer-sphere with ionic association.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2018.11a
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• pp.309-310
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• 2018

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2018.11a
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• pp.307-308
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• 2018

• Journal of the Korean Chemical Society
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• v.31 no.6
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• pp.534-541
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• 1987

The study of reaction mechanism for the substitution of ethylenediamine (en) for Cl and Hedta from $[CoCl(Hedta)]^-$ in the presence of $Hg^{2+}$ ion was carried out by uv and CD spectra. From the kinetic data, we proposed that the first ethylenediamine be substituted through the associative reaction path by means of interaction of $Hg^{2+}$ ion with Co(III), and that the second and the third ethylenediamine be substituted stepwise. From the optical purities of $[Co(en)_3]^{3+}$ which was formed after reaction, we suggested the critical stereochemical step and new substitution reaction paths.

• Bulletin of the Korean Chemical Society
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• v.35 no.11
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• pp.3244-3248
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• 2014

Two ethylenediamine cobalt(II) oxalate complexes Co(ox)(en), 1 and $Co(ox)(en){\cdot}2H_2O$, 2 have been hydrothermally synthesized and characterized by single crystal X-ray diffraction, IR spectrum, TG analysis, and magnetic measurements. In 1, Co atoms are coordinated by two bis-bidentate oxalate ions in transconfiguration to form Co(ox) chains, which are further bridged by ethylenediamine molecules to produce 2D grid layers, Co(ox)(en). In 2, Co atoms are coordinated by bridging oxalate ions in cis-configuration to form Co(ox) chains, and the additional chelation of ethylenediamine to Co atoms completes 1D zigzag chain, Co(en)(ox). Two lattice water molecules stabilize the chains through hydrogen bonding. Magnetic susceptibility measurements indicate that both complexes exhibit weak antiferromagnetic coupling between cobalt(II) ions with the susceptibility maxima at 23 K for 1 and 20 K for 2, respectively. In 1 and 2, the oxalate ligands afford a much shorter and more effective pathway for the magnetic interaction between cobalt ions compared to the ethylenediamine ligands, so the magnetic behaviors of both complexes could be well described with 1D infinite magnetic chain model.

• Journal of the Korean Chemical Society
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• v.33 no.2
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• pp.215-224
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• 1989

Electrochemical reductions of $trans-[Co(en)_2X_2](ClO_4)_n$ (where X is cyanide, nitrite, ammonia, and isothiocyanate) were investigated by cyclic voltammetry and polarography at mercury and glassy carbon electrode. $trans-[Co(en)_2(CN)_2]ClO_4$ was reduced to Co(II) complex followed by adsorption to the mercury electrode. Cyanide ion was not released from the reduced Co(II) complex but the cyanide and (en) were released after the reduction to metallic cobalt. The other complexes except $trans-[Co(en)_2(CN)_2]ClO_4$ were reduced to cobalt(II) complexes followed by release of monodendate ligand, and (en) was released at the reduction step to metallic cobalt. $trans-[Co(en)_2(NO_2)_2]ClO_4$ was reduced to cobalt(Ⅱ) complex, and $NO_2^-$ ion was released followed by electroreduction through ECE mechanism at pH 2. On glassy carbon electrode, all complexes of Co(III) were reduced to Co(II) complexes with irreversible one-electron diffusion controlled reaction in which (en) was not released at this step. Increasing absorption wave number of complexes caused to negative shift of peak potential.