Click Synthesis and Redox Chemistry of Mono- and Heterobimetallic Triazolyl and Triazolium-Ferrocene and Cobalticinium Complexes

Mono- and heterobimetallic triazolylferrocene and cobalticinium complexes and triazolium derivatives were synthesized by click reactions between the ethynylmetallocenes and benzyl azide or (azidomethyl)ferrocene followed by methylation reactions, respectively. Cyclic voltammetry data shed light on the electron-withdrawing character of the 1,2,3-triazolyl and triazolium substituents of the metallocenes, and cathodic reduction of the triazolium group was found to be irreversible even at 50 degrees C. Chemical reduction of orange triazolylcobalticinium hexafluorophosphate using NaBH4 yielded a mixture of red isomeric triazolyl eta(4)-cyclopentadienecobalt eta(5)-cyclopentadienyl complexes, whereas reduction by the single-electron reductant [(FeCp)-Cp-I(eta(6)-C6Me6)] yielded the brown 19-electron triazolylcobaltocene.