COMPLEXES OF COBALT(II) AND NICKEL(II) WITH D-ALDONIC AND D-ALDURONIC ACIDS IN AQUEOUS-SOLUTION

The equilibrium reactions between D-glucoheptonic, D-gluconic, D-galactonic, D-ribonic, D-glucuronic and D-galacturonic acids with cobalt(II) and nickel(II) ions have been studied by potentiometric methods in aqueous solution. All measurements were carried out at t = 20 degrees C and mu = 0.10 M, and the corresponding stability constants were calculated by applying the computer program BEST, The interactions between the proposed cations and these biological ligands are compared. As an indicator of probable structures of D-alduronic acid complexes, relaxation rate measurements on C-13 spectra of the ligand in the absence and presence of metal ion were performed.