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

Enhanced electrochemical resolution of anodic processes is possible in the presence of [N(Bu-n)(4)][B(C6F5)(4)], 1, as supporting electrolyte over that obtained in the presence of [N(Bu-n)(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 0.5 mmol dm(-3) solutions of [Ru-2(mu-FcCOO)(4)center dot(CH3CH2OH)(2)][PF6], 2, Fc = ferrocenyl, in CH2Cl2/[N(Bu-n)(4)][B(C6F5)(4)] were found to involve four well-resolved ferrocenyl- based electrochemical reversible redox processes as well as reduction of Ru-III-Ru-II. At 1.0 mmol dm(-3) concentrations of 2, or in the presence of [N(Bu-n)(4)][PF6], the four ferrocenyl processes coalesced into only two waves as a result of (Fc(+))center dot center dot center dot(PF6-) ion paring. Seventeen of the possible 18 one-electron transfer processes of the biscadmium trisphthalocyaninato complex [Cd-2{Pc(C6H13)(8)}(3)], 3, could be observed in THF/[N(Bu-n)(4)][B(C6F5)(4)], but the electrochemical window of CH2Cl2/[N(Bu-n)(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 (3n+)center dot center dot center dot(PF6-) prevented good resolution of oxidation processes. The CH2Cl2/[N(Bu-n)(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 beta-diketone FcC-OCH(2)CORc, 4, Rc = ruthenocenyl. In CH3CN/[N(Bu-n)(4)][PF6], the ruthenocenyl moiety was oxidised to a Ru-IV species. (C) 2010 Elsevier B.V. All rights reserved.