Thermodynamic and kinetic control over the electrochemical reduction of di(propylthiotetramethylcyclopentadienyl) titanium dichloride in tetrahydrofuran

The first reduction step of di(propylthiotetramethylcyclopentadienyl) titanium dichloride (Cp2′TiCl2) in THF solution has been investigated by cyclic voltammetry under steady-state conditions, cyclic voltammetry in diffusion and in thin layer. The results can be interpreted in terms of a square scheme with ligand-exchange chemical reactions. The thermodynamic and kinetic parameters have been obtained by simulation. The rate constants of the charge transfer, derived from the voltammetric curves, are rather slow (khi=0.025 cm s−1). The equilibrium Cp2′TiCl2+L/Cp2′TiClL++Cl− is determined by the fast recombination of the chloride ion and the cation (K1=2.4×10−11 M, kb1≅1011 M−1 s−1); whereas the equilibrium Cp2′TiCl2−+L/Cp2′TiClL+Cl− is in favour of the chloride ion departure (K2=0.01 M) with a fast reaction rate (kf2=1000 s−1).