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Journal of the Korean Chemical Society (JKCS)

ISSN 1017-2548(Print)
ISSN 2234-8530(Online)
Volume 36, Number 2
JKCSEZ 36(2)
April 20, 1992 

 
Title
Electrochemical Propertics and Oxidation Reaction of Hydrazobenzene by Oxygen Adducted Tetradentate Schiff Base Cobalt(Ⅱ)(3MeOSED) Activated Catalyst in Aprotic Solvents(Ⅰ)

비수용매에서 산소첨가된 네자리 Schiff Base Cobalt(Ⅱ)(3MeOSED) 활성촉매에 의한 Hydrazobenzene의 산화반응과 전기화학적 성질 (제 1 보)
Author
Ki-Hyung Chjo, Yong-Kook Choi, Sang-Bock Kim

조기형, 최용국, 김상복
Keywords
Abstract
네자리 Schiff base의 착물 Co(Ⅱ)(3MeOSED)(H2O)2을 합성하였다. 이 착물의 균일 산화 활성촉매로서 산소첨가 착물은 DMF와 DMSO 용매에서는 μ-peroxo형인 [Co(Ⅲ)(3MeOSED)(DMF)]2O2와 [Co(Ⅲ)(3MeOSED)(DMSO)]2O2이나 pyridine 용매에서는 superoxo형인 [Co(Ⅲ)(3MeOSED)(Py)]O2로 주어진다. 이들의 CV법과 DPP법에 의한 전기화학적인 특성으로 μ-peroxo형은 3단계 환원과정으로 일어나지만, superoxo형은 O2-의 prewave를 포함한 4단계 환원과정으로 일어난다. 산소가 포화된 메탄올 용액에서 [Co(Ⅲ)(3MeOSED)(L)]O2 (L: CH3OH)의 균일 산화 활성촉매에 의한 hydrazobenzene-(H2AB)의 산화 주생성물은 trans-azobenzene(t-AB)이 선택적으로 다음과 같은 반응식으로 생성되고 이 때 속도상수는 k = (2.96 ± 0.2) × 10-1M/sec임을 알았다. H2AB + Co (Ⅱ)(3MeOSED)(L)2+O2 ↔ [Co(Ⅲ)(3MeOSED)(L)]O2·H2AB → Co(Ⅱ(3MeOSED)(L)2+t-AB+H2O2

Tetradentate Schiff base Cobalt(Ⅱ)(3MeOSED)(H2O)2 complexe was synthesized and allowed to react with dry oxygen to form oxygen adducts of Cobalt(Ⅲ) complexes such as μ-peroxo type [Co(Ⅲ)(3MeOSED)(DMF)]2O2 and [Co(Ⅲ)(3MeOSED)(DMSO)]2O2 in DMF and DMSO or superoxo type [Co(Ⅲ)(3MeOSED)(Py)]O2 in pyridine. The oxygen adducted complex was investigated by cyclic voltammetry and DPP method with glassy carbon electrode in 0.1M TEAP-DMF (-DMSO,-Py) as supporting electrolyte solution. As a result the reduction reaction process occurred to four steps including prewave Of O2- in 1 : 1 oxygen adducted superoxo type [Co(Ⅲ)(3MeOSED)(Py)]O2 complex and three steps not including prewave of O2- in 1 : 2 oxygen adducted μ-peroxo type [Co(Ⅲ)-(3MeOSED)(DMF)]2O2 and [Co(Ⅲ)(3MeOSED)(DMSO)]2O2. A superoxo type [Co(Ⅲ)(3MeOSED)(L)]O2 (L: CH3OH) was generated with oxygen in methanol. Selectively oxidized hydrazobenzene (H2AB) to trans-azobenzene(t-AB) and the rate constant k for oxidation reaction of the following equation is (2.96 ± 0.2) × 10-1M/sec. H2AB + Co (Ⅱ)(3MeOSED)(L)2+O2 ↔ [Co(Ⅲ)(3MeOSED)(L)]O2·H2AB→Co(Ⅱ(3MeOSED)(L)2+t-AB+H2O2.

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