Analytical Sciences

Electrochemical Study of the Assisted Transfer of Silver Ion by 1,5-Cyclooctadiene at the 1,6-Dichlorohexane |Water Interface

Hajime KATANO, Hirosuke TATSUMI, and Takao HIBI

Department of Bioscience, Fukui Prefectural University, Matsuoka, Fukui 910-1195, Japan

The transfer of Ag⁺ ion across a polarized 1,6-dichlorohexane | water interface assisted by an alkene or olefin ligand, 1,5-cyclooctadiene (COD), was studied by cyclic voltammetry. Even if COD was absent from the organic phase, Ag⁺ ion gave a reversible voltammetric wave, and the formal potential of the non-assisted ion-transfer at the 1,6-dichlorohexane | water interface was determined from the reversible half-wave potential. By the addition of COD to the organic phase, the reversible half-wave potential shifted to more negative potentials with increasing concentration of COD. The concentration dependence of the half-wave potential revealed that the transfer of Ag⁺ ion is assisted by the formation of 1:1 and 1:2 Ag⁺-COD π-complexes in 1,6-dichlorohexane with overall formation constants of (2.1 ± 0.2) × 10³ M^-1 and (7.8 ± 1.0) × 10³ M^-2, respectively. The formal potential and the formation constants coincide well with those obtained by the potentiometry of Ag⁺ ion in aqueous and organic media with a Ag electrode.

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