Synthesis and electrochemical properties of a series of ferrocene-containing alcohols

• Published in: Polyhedron Vol. 24; no. 12; pp. 1611 - 1616
• Main Authors: Davis, Wade L., Shago, Rebotsamang F., Langner, Ernie H.G., Swarts, Jannie C.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 25.08.2005
• Subjects: Alcohol; Carboxylic acid; Cyclic voltammetry; Electrochemistry; Ferrocene; Synthesis; Cyclic voltammetry; Electrochemistry; Alcohol; Synthesis; Carboxylic acid; Ferrocene
• ISSN: 0277-5387
• DOI: 10.1016/j.poly.2005.04.022

Different synthetic methods towards a series of primary ferrocene-containing alcohols with m = 1–4 and two secondary alcohols are described. The dependency of formal reduction potentials on chain length has been determined; results are compared to the analogues carboxylic acid series. A series of primary ferrocenylalcohols, Fc–(CH 2) m –OH with m = 1–4 and Fc = ferrocenyl, was synthesised by reduction of the appropriate ferrocenylcarboxylic acids, Fc–(CH 2) n –COOH ( n = 0–3) and the ester methyl 4-ferrocenylbutanoate with LiAlH 4, the reduction of the γ-ketoacid ferrocylpropanoic acid, Fc–CO–(CH 2) 2–COOH, with AlCl 3/LiAlH 4, and the reduction of ferrocenylcarboxaldehyde, FcCHO, with NaBH 4. The secondary ferrocenyl alcohols CpFe(C 5H 4–CH(OH)–CH 3) and Fe(C 5H 4–CH(OH)–CH 3) 2 were obtained by NaBH 4 reduction of acetyl and diacetyl ferrocene. The different reduction methods are compared. The electrochemistry of the alcohols was studied by cyclic voltammetry in CH 3CN/0.1 M N( n Bu) 4PF 6 utilising a platinum working electrode. The ferrocenyl group showed reversible electrochemistry with the formal reduction potential ( E o′ versus Fc/Fc +) of the ferrocenyl group inversely proportional to side chain length. The influence of the side chain length on E o′ was more pronounced for the acids because the electron-withdrawing properties of the carbonyl group is stronger than that of the alcohol group. Ion pairing was found to play a major role in the electrochemical behaviour of ferrocenylmethanol, Fc–CH 2–OH.