Solvent and electrolyte effects in enhancing the identification of intramolecular electronic communication in a multi redox-active diruthenium tetraferrocenoate complex, a triple-sandwiched dicadmium phthalocyanine and a ruthenocene-containing β-diketone

Abstract: Enhanced electrochemical resolution of anodic processes is possible in the presence of [N( n Bu)4][B(C6F5)4], 1, as supporting electrolyte over that obtained in the presence of [N( n Bu)4][PF6]. By changing the anion of the supporting electrolyte to a salt having [B(C6F5)4]−, anions, electrochemical processes of especially cationic analytes can benefit. Thus, the redox chemistry of 0.5mmoldm−3 solutions of [Ru2(μ-FcCOO)4·(CH3CH2OH)2][PF6], 2, Fc=ferrocenyl, in CH2Cl2/[N( n Bu)4][B(C6F5)4] were found to involve four well-resolved ferrocenyl-based electrochemical reversible redox processes as well as reduction of RuIII–RuII. At 1.0mmoldm−3 concentrations of 2, or in the presence of [N( n Bu)4][PF6], the four ferrocenyl processes coalesced into only two waves as a result of (Fc+)⋯() ion paring. Seventeen of the possible 18 one-electron transfer processes of the biscadmium trisphthalocyaninato complex [Cd2{Pc(C6H13)8}3], 3, could be observed in THF/[N( n Bu)4][B(C6F5)4], but the electrochemical window of CH2Cl2/[N( n Bu)4][B(C6F5)4] only allowed detection of 15 of these processes. Although reduction processes were unaffected, THF solvation leading to species such as (3 n +)(THF) x with 1⩽ n ⩽4 and x ⩾1 as well as ion pair formation of the type (3 n +)⋯() prevented good resolution of oxidation processes. The CH2Cl2/[N( n Bu)4][B(C6F5)4] system also allowed detection of reversible one-electron transfer ferrocenyl (Fc/Fc+) and ruthenocenyl-based (Rc/Rc+) processes for both enol and keto isomers of the β-diketone FcCOCH2CORc, 4, Rc=ruthenocenyl. In CH3CN/[N( n Bu)4][PF6], the ruthenocenyl moiety was oxidised to a RuIV species. [Copyright &y& Elsevier]