MANGANESE(II) AND NICKEL(II) COMPLEXES OF SOME 2-(POLYHYDROXYALKYL)THIAZOLIDINE-4-CARBOXYLIC ACID-DERIVATIVES

The manganese(II) and nickel(II) ion coordination equilibria of some 2-(polyhydroxyalkyl)thiazolidine-4-carboxylic acid (PHTAC) derivatives were studied by potentiometric titration in the pH range 2-11. Nickel(II) parent complexes with (1, 1, 0) and (1, 2, 0) compositions and manganese(II) complexes with (1, 1, 0) composition were formed. In both systems, mixed-ligand complexes involving hydroxide ion coordination and/or further deprotonation of the alcoholic hydroxy groups of the sugar moieties were observed at pH > 6. EPR measurements indicated that in alkaline solution all the manganese(II)PHTAC complexes are dimeric. The magnitudes of the complex-formation constants were shown to depend on the conformation of the hydroxy groups on the first carbon atoms of the polyol chains.