Ferrocene- and ruthenocene-containing chalcones: A spectroscopic and electrochemical study

Chalcones of the type Mc-CO–CHCH-Ph, Ph-CO–CHCH-Mc and Mc-CO–CHCH-Mc with Mc = Fc = ferrocenyl or Rc = ruthenocenyl, and Ph = phenyl were synthesized. Synthesis was achieved by base catalyzed Claisen–Schmidt condensation of the appropriated acetyl and aldehyde in ethanol. Cyclic voltammetry in CH3CN in the presence of 0.1 mol dm−3 [N(Bu)4][PF6] revealed chemical and electrochemical reversible behaviour for the Fc/Fc+ couple and irreversible electrochemistry for the two electron Rc/Rc2+ couple. The potential ranges for the Fc/Fc+ couple varied in the range 138 ⩽ E°′ ⩽ 302 mV while Epa for Rc/Rc2+ couple was between 358 and 510 mV vs. FcH/FcH+, the internal standard. Chalcones with the carbonyl group adjacent to the metallocene, are more difficult to oxidize.