Extractions and Spectroscopic Studies of Various Metals with Diglycolamide-Type Tridentate Ligands

Three tridentate extractants and three masking reagents including O, N, and S donors have been developed and their properties are compared and discussed. The extractants are N,N,N′,N′-tetraoctyl-diglycolamide (TODGA), methylimino-N,N′-dioctylacetamide (MIDOA) and N,N,N′,N′-tetraoctyl-thiodiglycolamide (TDGA(C8)) together with masking agents having the same central frame but with short alkyl chains. The results of the present study indicate that TODGA can extract mainly hard acid metals belonging to groups 2-4,13-15 in the periodic table. MIDOA can extract soft acid metals and oxyanions (groups 5-10, 16), and TDGA can extract soft acid metals (groups 10-11). Some spectrophotometric studies (UV-vis., IR, and NMR) indicate the stoichiometry and the effect of donor atoms for metal-complexation. The ΔHf values, the heat generation during complex formation, obtained by chemical calculation by DFT theory show a reverse-correlation with their extraction ability.