Polarographic study of stability constant and thermodynamic parameters of [Mn-L-amino acidate-vitamin-PP] system vis-à-vis electrode kinetics

Electrochemical Laboratory, Department of Chemistry, Dr. H. S. Gour University, Sagar-470 003, Madhya Pradesh, India E-mail: faridkhanS8@yahoo.com, farid.fk@reddifmail.com Manuscript received 6 August 2009, revised 18 February 2010, accepted 25 February 2010 The polarographic behavior of complexes of Mnll with glycine, α-alanine; L-leucine, L-valine, L-asparagine and L-glutamine as primary ligands and vitamin-PP (nicotinamide) as secondary ligand was studied using manual polarography at pH = 7.30 ± 0.01, µ= 1.0 M NaClO4 at 25 ºC and 35 ºC. MnII funned 1 : 1 : 1, 1 : 1 : 2 and 1 : 2 : 1 complexes with these ligands as confirmed by Schaap and McMaster method. The sequence of the stability constant of complexes was L-glutamine < L-asparagine < L-valine < L-leucine < α-alanine < glycine, log of which varied from 1.68 to 9.45. The kinetic parameters are determined using Tamamashi and Tanka method. The transfer coefficient (II) varied from 0.40 to 0.55 (0.50) confirmed that transition state behaves between reactant and product response to applied potential and it lies always between dropping mercury electrode and solution Interface. The waves were characterized as being quasireversible with diffusion controlled. The thermodynamic parameters enthalpy change (ΔH), free energy change (ΔG) and entropy change (ΔS) also determined