The peculiarities of high-molecular complex compounds of metal ions with fibrous complexites in water-organic mixtures

The results of equilibria studies of formation of high-molecular complex compounds (HMCC) of transition metal ions (Cu2+, Co2+, Ni2+) with fibrous complexites when ionic strength is 0.05 at temperature range of 298-358 K in mixed solvents of variable composition are reported as the function of a solvent composition. The experiments were carried out by the potentiometric method in water - methanol and water - dimethylsulfoxide mixtures. Under a complexite the author implies a fibrous matrix formed on the basis of a cellulose that contains amidoxime and hydroxamic groups. The composition was stated, stability constants (log K-st) and thermodynamic characteristics (Delta GD(st)(0), DeltaH(st)(0), DeltaS(st)(0)) of complex formation were calculated. The HMCC are characterised by spectra of electronic reflection and infrared spectra. The values of log K-st increase with the decrease of the dielectric constant (E) of the solvent. It was found that the dependence of a log K-st is not linear. The addition of the protolytic solvent that results in the stability increase of the complexes is stated. The influence of the addition of the aprotic polar component of a mixed solvent depends to some extent on the nature of the metal ion. The change of both HMCC structure and its geometry is shown not to be affected by the solvent. The results obtained are discussed in terms of the solvolytic ability of a solvent as well as of the effect of specific polymeric factors. (C) 2001 Elsevier Science B.V. All rights reserved.