Synthesis and Electrochemical Behavior of Ferrocenyl β‐Ketoamines FcC(O)CH=C(NH(C6H4‐4‐R'))R.

FcC(O)CH=C(OH)R (1, R=Me; 2, R=Fc; Fc=Fe(η5‐C5H4)(η5‐C5H5)) reacts with 1‐H2N‐4‐R'‐C6H4 (3 a, R'=Me; 3 b, R'=OMe; 3 c, R'=C≡N; 3 d, R'=F) producing β‐ketoamines FcC(O)CH=C(NH(C6H4‐4‐R'))R (4 a–d, R=Me; 5 a–d, R=Fc). Electrochemistry shows that 4 a–d possess one (4 a: E°′=90 mV; 4 b: E°′=80 mV; 4 c: E°′=145 mV; 4 d: E°′=95 mV) and 5a–d two (5 a: E°′1,2=90, 305 mV; 5 b: E°′1,2=85, 305 mV; 5 c: E°′1,2=155, 360 mV; 5 d: E°′1,2=105, 325 mV) reversible redox processes. In 5 a–d electrostatic interactions occur among Fc/[Fc]+ as oxidation progresses, as evidenced by UV/vis‐NIR spectroscopy. Compounds 4 a,d and 5 b,c display an irreversible N‐oxidation at 1100–1450 mV, while 4 b owns a reversible event at 910 mV. A linear relationship between the σ Hammett constants and the E°′1 values exists. [ABSTRACT FROM AUTHOR]