Three-Phase Electrochemistry of a Highly Lipophilic Neutral Ru-Complex Having a Tridentate Bis(benzimidazolate)pyridine Ligand

Here we describe the synthesis and electrochemical testing of a heteroleptic bis(tridentate) ruthenium(II) complex [Ru^II(LR)(L)]⁰ (LR =2,6-bis(1-(2-octyldodecan)benzimidazol-2-yl)pyridine, L = 2,6-bis(benzimidazolate)pyridine). It is a neutral complex which undergoes a quasireversible oxidation and reduction at relatively low potential. The newly synthetized compound was used for studies of ion-transfer at the three-phase junction because of the sensitivity of this method to cation expulsion. The [Ru^II(LR)(L)]⁰ shows exceptional stability during cycling and is sufficiently lipophilic even after oxidation to persist in the organic phase also using very hydrophilic anions such as Cl⁻. Given its low redox potential and strong lipophilicity this compound will be of interest as an electron donor in liquid-liquid electrochemistry.