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Journal of the Korean Chemical Society (JKCS)

ISSN 1017-2548(Print)
ISSN 2234-8530(Online)
Volume 39, Number 4
JKCSEZ 39(4)
August 20, 1995 

Stereoselective Electron Transfer Reactions between Optically Active △-cis-[Co(en)2(NO2)2]+ and rac-[Co(Y)]2-(Y=EDTA, PDTA, CyDTA)
Bae-Wook Lee, Dong-Yeub Kim, Dong-Jin Lee, Chang-Eun Oh, Myung-Ki Doh*
수소이온 존재하에서 cis-[Co(en)2(NO2)2]+과 라세미-[Co(Y)]2-(Y=EDTA, PDTA,CyDTA)간에 일어나는 전자전달반응속도를 조사하였다. 속도자료로부터 cis-[Co(en)2(NO2)2]+과 라세미-[Co(Y)]2-간에 일어나는 전자전달반응은 수소이온이 촉매로 작용하여 내부권으로 진행되는 것을 알 수 있었다. 한편, 광학활성인 △-cis-[Co(en)2(NO2)2]+과 라세미-[Co(Y)]2-(Y=EDTA, PDTA,CyDTA)간의 입체선택적 전자전달반응에서는 △-[Co(EDTA)]-, △-[Co(PDTA)]- and △-[Co(CyDTA)]-가 각각 6.0, 2.9, 3.0% e.e.(e.e.=enantiomeric excess) 생성되었다. 이것은 두 착물이 접근하여 먼저 선택적 이온회합을 이루고 전자전달반응이 일어나는 것으로 불 수 있다. 따라서 △-cis-[Co(en)2(NO2)2]+과 라세미-[Co(Y)]2-간의 입체선택적 전자전달반응은 산촉매에 의한 내부권 반응과 입체선택적 이온회합에 따른 외부권 반응으로 진행된다고 추정할 수 있다.

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.

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