5 mL of a 1.53 x 10-2 M solution of the ligands, in CH2Cl2 stabilized with amylene, were equilibrated under magnetic stirring, in a centrifuge test tube, with 7.65 x 10-2 mmoles of solid ammonium salts for 2 h. After centrifugation an aliquot of 3 mL of solution was withdrawn, diluted with 30 mL of methanol, acidified with 6N- HNO3 and potentiometrically titrated with a 10-2 M solution of AgNO3. Values are within ± 5% error.