ABSTRACT
Electrochemical Advances Using Fluoroarylborate Anion Supporting Electrolytes Frédéric Barrière,1 Robert J. LeSuer, William E. Geiger* 2
1 INTRODUCTION
1.1 Role of Supporting Electrolytes
A supporting electrolyte is required in virtually every experiment involving molecular electrochemistry [1-3]. Exceptions to this (e.g., through use of an ultra-microelectrode [4]) may be found when the voltammetric currents are sufficiently low to approach potentiostatic conditions, but even in those cases it is assumed that adventitious ions are present to carry the current. In the vast majority of cases, an electrochemically suitable electrolyte [5] is prepared by adding to the solvent a salt in 50-100 fold excess over that of the electroactive compound (i.e., the analyte). Within the context of nonaqueous solvents, the most important supporting electrolytes are those comprised of anions such as [C104]-, [BF4]-, [PF6]- and [CF3SO3]- as tetraalkylammonium salts. The use of these anions became standard practice over four decades ago [3], so that their [NR4]
+ salts may now be referred to as 'traditional' supporting electrolytes. It is fair to say that the choice of a supporting electrolyte had become a pragmatic, rather than an intellectual, matter. The purpose of this Chapter is to discuss very recent developments involving a new family of salts which promise to supplant the traditional electrolytes under many experimental conditions, especially those
involving lower-polarity solvents having dielectric constants (e) of about 10 or less. The crucial characteristic of the new electrolyte family is the inclusion of relatively large anions of very low nucleophilicity.
