Synthesis, characterization and electrochemical behavior of new bis(fluoroalkyl) ferrocenylphosphonates and their tin tetrachloride complexes

International audience; The synthesis of fluoroalkyl and non-fluorinated long chain alkyl ferrocenylphosphonates of the type FcP(O)(OR)2 (Fc: ferrocenyl; R = CH2CF3 (1), CH2C2F5 (2), Et (3) n-Hex (4), n-Hep (5) and n-Oct (6)) from reaction of ferrocene with corresponding phosphorochloridates is reported. The ferrocenyl phosphonates 1-4 were used as ligands, which reacted with tin(IV) chloride to produce the new complexes [SnCl4(1)2] (7), [SnCl4(2)2] (8), [SnCl4(3)2] (9) and [SnCl4(4)2] (10). All these ferrocenylphosphonate derivatives were characterized with multinuclear (1H, 13C, 19F, 31P and 119Sn) NMR, IR and UV-visible spectroscopic techniques. The electrochemical behavior of these compounds was investigated using cyclic voltammetry (CV); the results show that fluoroalkyl groups render the reverse one-electron transfer oxidation reaction more difficult (ΔE1/2 = 310–330 mV) as compared to non-fluorinated alkyl groups (ΔE1/2 = 215–261 mV). Preliminary results from CV measurements on the viability of ferrocenyl-containing tin(IV) complexes 7–10 as sensitizers for TiO2-based dye sensitized solar cells are also described.