Synthesis of electroactive multinuclear dipyrrinato complexes and Fe(III) assisted formation of α-alkoxy substituted 5-ferrocenyldipyrromethenes

Abstract

The synthesis and characterization of multinuclear complexes [Pd(acac)(fcdpm)] (1), [Pd(fcdpm)₂] (2), [Co(acac)(fcdpm)₂(3), [Co(fcdpm)₃] (4) and α-alkoxy derivatives [α-OMe-fcdpm] (5), [α-OEt-fcdpm] (6), [α-OPrⁿ-fcdpm] (7) and [α-OBuⁿ-fcdpm] (8) (fcdpm = 5-ferrocenyldipyrromethene; acac = acetylacetone) have been described. Formation of alkoxy derivatives 5–8 takes place from highly selective Fe(III) mediated alkoxylation of fcdpm in alcohol. It has been established that yield of α-alkoxy derivatives depend on the alcohol chain length. The compounds under study have been characterized by elemental analyses, spectral (IR, ¹H, ¹³C NMR, ESI-MS, UV-vis) and electrochemical studies (CV and DPV). Structures of 1, 3 and 5 have been verified by X-ray single crystal analyses. Structural studies revealed distorted square planar and octahedral geometry about Pd(II) and Co(III) centres. All the compounds exhibited oxidation wave due to Fc/Fc⁺ redox couple (0.34–0.36, 1–4; 0.24–0.25 V, 5–8).