Equilibrium and spectroscopic studies of transition metal complexes of sugar-containing thiazolidine derivatives

Abstract

Transition-metal co-ordination equilibria of 2(RS)-D-galactothiazolidine-4(R)-carboxylic acid were studied by potentiometric titrations in the range pH 1.5–8.5. In most cases, (1,1,1), (1,2,0) and (1,2,0) parent complexes M_pL_qH_r were formed, but in the cases of oxovanadium(IV), manganese(II) and zinc(II) at >pH 6 mixed-ligand complexes involving hydroxide-ion co-ordination or further deprotonation of alcoholic hydroxy groups were also observed. EPR measurements indicated that the manganese(II) complex is dimeric, while that of VO²⁺ is monomeric.