Further Investigation on Preparation, Structure and Electrochemical Properties of N-Alkyl- and N-Aryl-2-aza-[3]-ferrocenophanes

摘要

The reactions of 1,1'-bis (hydroxymethyl) ferrocene with primary amines such as 6-aminohexanol, cyclohexylamine, 4-phenylbutylamine, 2-isopropylaniline, 4-(trifluoromethyl) benzylamine, and 1-aminomethylferrocene in the presence of [RuCl_2(PPh_3)_3] catalyst led to intermolecular condensation of the CH_2OH and NH_2 groups to afford N-alkyl-or N-aryl substituted 2-aza-[3]-(1,1')-ferrocenophances. Cyclic voltammograms of the obtained N-alkyl-2-aza-[3]-(1,1')-ferrocenophanes exhibit reversible redox of the Fe center at E_(1/2) = -0.01 -+0.04V (vs Ag~+/Ag) and subsequent irreversible oxidation of the amino group of the ligand at E_(ox) = 0.41-044 V. N-(4-Hydroxyphenyl)-2-aza-[3]-(1,1')-ferrocenophane shows two pairs of reversible electrochemical oxidation and reduction at E_(1/2) = 0.04 and 0.44V. The latter potential is significantly lower than t he corresponding electrochemical oxidation of N-aryl-2-aza-[3]-(1,1')-ferrocenophanes (0.68-075 V). The N-alkyl-2-aza-[3]-(1,1')-ferrocenophanes react with MeI to cause methylation of the amino group to produce cationic 2-aza-[3]-(1,1')-ferrocenophanes containing a quaternary nitrogen center. The iodo counter anion is easily replaced with BF_4~- or PF_6~-. Cyclic voltammograms of the cationic ferrocenophanes show the redox between ferrocene and ferrocenium at E_(1/2) = 0.37-0.42V.