• Bulletin of the Korean Chemical Society
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• 제23권6호
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• pp.903-907
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• 2002

• 대한화학회지
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• 제30권1호
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• pp.84-89
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• 1986

주게원자가 ONNO인 새로운 네자리 리간드인 ethylenediamine-N,N'-di-${\alpha}$-isobutyric acid(eddib)를 합성하고 이 리간드의 디클로로 코발트(III)착물을 공기산화법에 의하여 합성하였다. Eddib리간드가 코발트(III)이온에 배위될 때 S-cis이성체만이 선택적으로 만들어짐이 관찰되었는데 이것은 ring strain과 steric hinderance 때문이다. 그리고 eddib의 디클로로 코발트 (III)착물을 용액중에서 $[Co(eddib)L]^{n+}$ $(L = Cl{\cdot}(H_2O),\;CO_3^{2-},\;(H_2O)_2)$로 치환반응을 시켰을 때 이들의 흡수 스펙트럼의 흡수띠 위치가 분광학적계열과 일치함을 알 수 있었다. 합성된 착물의 구조는 원소분석, 적외선 흡광분석법, 핵자기 공명 및 전자흡수 스펙트럼으로 확인하였다.

• 한국재료학회지
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• 제10권1호
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• pp.55-61
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• 2000

$UO_2$분말에 PVA-Al(III) 착물과 AlOOH를 각각 0.03~1.0wt%를 첨가하여 소결체를 제조한 후 소결체 특성을 비교하였다. PVA-Al(III) 착물과 AlOOH는 $1000^{\circ}C$의 소소분위기에서 열분해하는 경우 생성상은 $\theta-Al_2O_3$이었다. 순수 $UO_2$분말에 비해 AlOOH가 첨가된 혼합 분말의 곁보기 밀도는 더 높았고, PVA-Al(III) 착물이 첨가된 혼합 분말은 더 낮은 겉보기 밀도를 보였다. AlOOH가 첨가된 소결체의 경우 약 $800^{\circ}C$ 부근에서 치밀화가 시작되었지만, PVA-Al(III) 착물이 첨가된 소결체의 경우에는 약 $900^{\circ}C$에서 치밀화가 시작되었다. 기공 크기 분포는 AlOOH가 첨가된 $UO_2$소결체의 경우에 monomodal 형태로, 그리고 PVA-Al(III) 착물의 첨가된 소결체의 경우에는 bimodal 형태로 나타났다. 결정립 크기는 1wt% 첨가시 AlOOH가 첨가된 $UO_2$소결체의 경우에 약 $13\mu\textrm{m}$이었지만, PVA-Al(III) 착물의 첨가된 소결체의 경우에는 약 $\36mu\textrm{m}$까지 성장하는 현저한 효과를 확인하였다.

• Bulletin of the Korean Chemical Society
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• 제32권5호
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• pp.1729-1732
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• 2011

• Bulletin of the Korean Chemical Society
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• 제28권8호
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• pp.1299-1304
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• 2007

New sulfur functionalized cyclopentadiene ligands, 1-[2-(thioanisole)]-2,5-dimethylcyclopentadiene (3), 1-[2- (thioanisole)]-2,3,5-trimethylcyclopentadiene (4), and 1-[2-(thioanisole)]-2,3,4,5-tetramethylcyclopentadiene (5), were prepared. In these ligands, the S-donor atom is connected to a cyclopentadiene ring by a rigid phenylene spacer. CpCo(III)-diiodo half-sandwich complexes (6-8) were obtained from reaction the ligands (3- 5) with Co2(CO)8, followed by treatment of I2. Substitution reaction of CpCo(III)-diiodo complexes with MeLi yielded the corresponding CpCo(III)-dimethyl complexes (9-11). Further transformation to the corresponding cationic cobalt complexes (12-14) were achieved by reaction of the CpCo(III)-dimethyl complexes with HB(ArF)4·2Et2O and trapping with CD3CN. The new sulfur functionalized cyclopentadiene ligands having a rigid phenylene spacer and the corresponding cobalt complexes were characterized by 1H, 13C and 19F NMR spectroscopy. The diiodo Complex 6 was also characterized by a single crystal X-ray diffraction method.

• 대한화학회지
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• 제30권4호
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• pp.377-382
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• 1986

광학활성인 ${\Delta}-[Co(en)_3]^{3+}$ion을 이용하여 라세미체인 $[Co(ox)_3]^{3-}$ 이온을 광학분할한 후 얻어진 ${\bigwedge}-[Co(ox)_3]^{3-}$ 이온의 라세미화를 여러가지 혼합용매 즉, 물-유기용매(유기용매=에탄올, 이소푸로필알코올, 아세톤 및 디옥산)내에서 조사하였다. 라세미화속도는 물<에탄올<이소프로필 알코올<디옥산의 순서로 증가하였고 그 순서는 첨가한 유기용매의 polarizability의 증가순서와 일치하였다. 이상의 결과와 ${\Delta}H^{\neq}$와 ${\Delta}S^{\neq}$를 고려하면 ${\bigwedge}-[Co(ox)_3]^{3-}$의 라세미화메카니즘은 가능한 라세미화메카니즘중 twist메카니즘으로 진행됨을 알 수 있었다.

• 한국산업융합학회 논문집
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• 제3권1호
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• pp.77-82
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• 2000

The stereoselective ligand exchange reaction of trans-$[Co(SS-epm)Cl_2]^+$ and racemic propane-1,2-diamine (rac-pn) produces the complex that is identified as $[CO(N)_6]^{3+}$ type of $[Co(SS-epm)(pn)]^{3+}$ by absorption spectrum. It is conceivable that the reaction mechanism involves substitution and isomerization. The calculated and experimentally determined ratios of the complexed enantiomeric substrates at equilibrium were as follows: $[Co(SS-epm)(pn)]^{3+}$,calcd 32 % / 68 %, exptl 19 % / 81 % R-pn / S-pn. It has been shown that the employment of molecular mechanics calculations as a predictive tool may lead to the design of chiral complexes that may be applied to the separation of racemic mixtures of simple bidentate ligands.

• Bulletin of the Korean Chemical Society
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• 제21권4호
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• pp.405-411
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• 2000

Electrochemical and spectroelectrochemical studies of cobalt-Schiff (Co-SB) base complexes, Co(salen) [N-N'-bis(salicylaldehyde)-ethylenediimino cobalt(II)] and Co(salophen) [N-N'-bis(salicylaldehyde)-1,2-pheny-lenediimino cobalt(II)], have been c arried out to test them as oxygen reduction catalysts. Both compounds were found to form an adduct with oxygen and exhibit catalytic activities for oxygen reduction. Comparison of spec-tra obtained from electrooxidized complexes with those from Co-SB complexes equilibrated with oxygen in-dicates that the latter are consistent with the postulated complex formed with oxygen occupying the coaxial ligand position, namely, Co(III)-SB·O2 - .The catalysis of oxygen reduction is thus achieved by reducing Co(III) in the oxygen-Co-SB adduct, releasing the oxygen reduction product, e.g., O2 - ., from the Co(II)-SB complex.

• 대한화학회지
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• 제51권6호
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• pp.595-599
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• 2007

• Bulletin of the Korean Chemical Society
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• 제19권4호
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• pp.457-462
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• 1998

A chiral pentadentate bis-amide ligand, 1,9-bis(S)-pyrrolidinyl-2,5,8-triazanonane-1,9-dio ne$(S,S-prodienH_2)$ has been synthesized from the reaction of bis(2-aminoethyl)amine(dien) and S-proline, and the structure of $[Co(S,S-prodien)H_2O]ClO_4$ has be en determined by single crystal X-ray diffraction. The geometrical structure of the Co(III) complex has been an αβ -form, where the dien moiety of ligand chelates to a facial in metal center, and the aqua ligand coordinates a cis site to the secondary nitrogen of dien. The Co-N(1), Co-N(3) distances of two amide moiety in S,S-prodien are shorter than the other Co-N(2), Co-N(4), and Co-N(5) distances because of the increased basicity of nitrogen in amide. The complex crystallizes in the monoclinic space group $P2_1$(#4), with a=7.838(1), b=12.675(1), c=9.710(1) Å, β=100.39(1) and z=2. Refinement gives the final R and $R_w$ values of 0.045 and 0.057, respectively for 2130 observed reflections. Based upon the CD and X-ray data, it is identified that the absolute configuration of the αβ -$[Co(S,S-prodien)H_2O]ClO_4$ has a Λ-form.