KOH; KNO3 in water soln. of aliphatic acid in H2O mixed with soln. of metal salt at 25+/-0.1°C under N2 atm.; ionic strength was kept const. using soln. of 0.1 M KNO3; pH was adjusted with soln. of KOH; complex formed at pH 3.0-4.5; not isolated; monitored by pH-metric titration;