Syntheses, characterization of and studies on the electrochemical behaviour of ferrocenyl dithiophosphonates and 4-methoxyphenyl dithiophosphonates

Abstract

Some 1,3-dithiadiphosphetane 2,4-disulfides (X2P2S4, X: Fc, FcLR; X: CH3OC6H4, LR) were allowed to react with alcohols to obtain dithiophosphonic acids (X(OR)PS2H). These were converted to the corresponding ammonium salts. The salts were of the structures [Fc(OR)PS2](-)[NH4](+), R: 3-methyl-1-butyl- for I; 1-phenyl-1-propyl- for II; 3-pentyl- for III; 3-phenyl-1-propyl- for IV and [CH3OC6H4(OR)PS2](-)[NH4](+), R: 3-methyl-1-butyl- for V and 1-phenyl-1-propyl- for VI. To the best of our knowledge, all the compounds except V were prepared for the first time.The compounds synthesized were characterized by elemental analysis, NMR (H-1, C-13, P-31), MS, FTIR, and Raman spectroscopies. Electrochemical behaviors of I-VI at disposable pencil graphite electrode (PGE) were investigated by using cyclic voltammetry (CV) and square-wave voltammetry (SWV). Adsorption and diffusion patterns of all the compounds on the PGE were also studied.Two electroactive groups were identified in the compounds I-IV and only one in V and VI. The ferrocenyl groups of I-IV were oxidized at around 0.4V. The same compounds display a second, more intense CV band at 0.8V. The corresponding band for the compounds V-VI appears at around 0.6V with a much weaker intensity. It is suggested that the ferrocenyl group introduced into the structures stabilizes the radical species formed as the product of the oxidation of the dithiophosphonato group.