Studies of electrode kinetics of mixed ligand complexes of Ni(II) in tetrahydrofuran (THF) at DME

The reduction of synthesized mixed ligand complexes of Ni(II) with pyridines and halides and pseudohalides have been studied at dropping mercury electrode in different percentages (v/v) of tetrahydrofuran (THF). The reduction of each of these complexes, i.e. Ni(beta-PiC)(4) (NCS)(2), Ni(gamma-PiC)(4) (NCS)(2), Ni(PY)(4) (NCS)(2), Ni(beta-PiC)(4) Cl-2, Ni(gamma-Pic)(4) Cl-2, Ni(PY)(4) Cl-2 was found to be diffusion controlled. The slope values indicate the reduction to be irreversible. This was further confirmed by the plot of E-1/2 vs log t, which indicates a change of E-1/2 with drop. time or height of mercury column. The kinetic parameters (K-fh(0) cm and xi) of these complexes have been calculated by using Meites-Israel method and its modifications by Gaur-Bhargava's method. The results of the kinetic parameters suggest that with the increase in percentages of the solvent (upto 60%) the reduction takes place irreversibly. Moreover, the reduction of the aquo-nickel ion takes place more irreversibly than that of nickel complexes.