Amide Tricobaltcarbon Clusters With Multiple Redox Centers

Abstract

The complexes FcNHC (O)CCo₃(CO)₉ ( Fc = ferrocenyl ) (3) and Fc ( alaOMe )C(O)CCo₃(CO)₉ (ala = alanine ) (5) have been synthesized from the ⁺C(O)CCo₃(CO)₉ cation and FcNH₂ or Fc ( alaOMe )H respectively. Derivatives FcNHC (O)CCo₃(CO)₆[P( OPh )₃]₃ (4) and Fc ( alaOMe )C(O)CCo₃(CO)₆[P( OPh )₃]₃ (6) are also described. Analysis of the spectroscopic and redox behaviour shows that the amide linkage acts as a -I, -M substituent group to Fc and the Co₃C unit acts as a-I, +M group. Unlike complexes where these redox centres are directly linked, electronic effects are not transmitted between Co3C and Fc . Oxidation at the ferrocene centre and reduction at the Co₃C centre in (3) and (5) is chemically reversible whereas oxidation of the amino acid moiety is irreversible; oxidation of the cluster takes place in (4) and (6) but no intervalence charge transfer is observed.