6533b825fe1ef96bd128201c

RESEARCH PRODUCT

Ion Pairing in the Analysis of Voltammetric Data at the ITIES: RbTPB and RbTPBCl in 1,2-dichloroethane

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The association of rubidium-tetraphenylborate (RbTPB) and rubidium-tetrakis(-chlorophenyl)borate (RbTPBCl) ion pairs in the organic solvent 1,2-dichloroethane (DCE) have been obtained from condutivity and voltammetric data. Conductivity measurements given K RbTPBCl =43 100 M -1 and yield a lower bound for K RbTPB (K RbTPB > 70000 M -1 ). The latter association constant is at variance with the previously accepted value. A method for analysing voltammetric data which allows for the determination of the association constants is presented. The positive polarization limit where the transfer of Rb + takes place is shifted by ca. 200 mV when changing the anion of the organic base electrolyte from TPB - to TPBCl - . If we interpret this shift in terms of the association constant, then K RbTPB =7.4.10 7 M -1 . The values of K RbTPB and K RbTPCl are discussed in terms of the classical theories by Bjerrum and Fuoss. Finally, we consider if the preferential solvation of p-chlorophenyl rings of TPBl - could account for the observed difference between the values of the association constants.