Voltammetric study of the interfacial electron transfer between bis(butylcyclopentadienyl)iron in 1,2-dichloroethane and hexacyanoferrate in water

The electron transfer (ET) reaction between bis(butylcyclopentadienyl)iron(II) ([FeII(C5H4Bu)2]) in 1,2-dichloroethane (1,2-DCE) and the hexacyanoferrate redox couple ([FeII/III(CN)6]4−/3−) in water (W) at the 1,2-DCE∣W interface has been studied by use of normal pulse voltammetry and cyclic voltammetry. In normal pulse voltammetry, S-shaped current vs. potential curves with well-defined limiting currents attributable to the interfacial ET reaction were observed. The voltammetric results can be explained well by the theoretical equations [M. Senda, Rev. Polarogr. (Jpn), 49 (2003) 219; 50 (2004) 60] according to a so-called IT-mechanism, that is, the [FeII(C5H4Bu)2] molecule is transferred from the 1,2-DCE to the W phase across the interface, then the ET reaction takes place homogeneously in the W phase between [FeIII(CN)6]3−(W) and [FeII(C5H4Bu)2](W) to produce [FeII(CN)6]4−(W) and [FeIII(C5H4Bu)2]+(W), which is followed by the transfer of the [FeIII(C5H4Bu)2]+ ion from the W to the 1,2-DCE phase across the interface to give the voltammetric current. Experimental results from cyclic voltammetry are also explained well by the IT-mechanism.