A Polarographic Study of Nickel-Monoethanolamine Complex

Ni-Monoethanolamine 착염의 폴라로그라피-

Polarographic studies of Ni(II) ion complexed with monoethanolamine, MEA, in aqueous solution have been carried out using sodium perchlorate as a supporting electrolyte. With use of D. C. and A. C. polarograms polarographic behaviors of the complex have been discussed. The wave obtained from basic solutions are found to be well defined and reversible, while reduction of the complex at pH smaller than 8.8 seems to be kinetic controlled with different complex species. Reducing species of the complex on the mercury electrode is determined to be $Ni(MEA)_3OH$ instead of $Ni(MEA)_2(OH)_2$ which is reported by other workers. Overall stability constant of $Ni(MEA)_3OH$ is obtained to be $10^{20}.$

Ni(II)-Monoethanolamine(MEA)錯鹽의 水銀電極表面에 있어서의 還元反應의 反應機構를 폴라로그라프법을 써서 解明하였다. 이 錯鹽의 電極環元의 可逆程度를 直流 및 交流 폴라로그람으로 檢討하였더니 pH가 9.0보다 낮은 範圍에서는 錯鹽의 反應電流로 推測되는 非可逆性波를 나타니고 pH $9.5{\sim}11.0$ 사이에서는 Cd(II)波에 相當하는 比較的 可逆的인 well defined wave를 얻었다. MEA의 濃度와 pH를 變함으로서 얻은 波를 檢討한 結果 還元波는 이를 ligands와 빠른 平衡에 있는 Ni錯鹽에 基因하고 이 錯鹽의 化學式은 $Ni(MEA)_3OH$이고 總安定度常數는 約 $10^{20}$임을 밝혀내었다.