Stability Dependence on Redox–active Site Structure in Free Catechol‐ or Hydroquinone–substituted Polypyridylruthenium(II) Complexes

Abstract Polypyridylruthenium(II) complexes with redox‐active, structurally isomeric catechol or hydroquinone units were newly prepared to examine the structure‐stability relationships in the redox‐active sites. A marked difference based on the structure of the active site was confirmed with respect to the formation of the oxidized forms, i. e. the quinone complexes: only the para ‐isomer was completely converted into the corresponding quinone form. The conversion of Ru II to Ru III was not observed. Redox‐mediated interconversion between the hydroquinone and para ‐quinone units is also reported.