Transition metal ions and amides. VIII. Discrimination between different models for the complexation of Cu2+ with N, N′-diglycyl 1, 2-ethanediamine, N, N′-diglycyl-1, 3-propanediamine and glycine ethylamide by potentiometric or by spectrophotometric titration
✍ Scribed by Markus Briellmann; Andreas D. Zuberbühler
- Publisher
- John Wiley and Sons
- Year
- 1982
- Tongue
- German
- Weight
- 557 KB
- Volume
- 65
- Category
- Article
- ISSN
- 0018-019X
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✦ Synopsis
Abstract
The complexation of Cue^2+^ with 1, 8‐diamino‐3, 6‐diaza‐2, 7‐octanedione (__N, N′‐diglycyl‐1, 2‐ethanediamine, DED) and with 1, 9‐diamino‐3, 7‐diaza‐2, 8nonanedione (__N, N′‐diglycyl‐1, 3‐propanediamine, DPD) has been studied by potentiometric and by spectrophotometric titration. With both ligands L the complexation to Cue^2+^ leads to relatively complicated equilibria with CuLH^3+^, CuL^2+^, CuLH^−2^, and dimeric Cu~2~L complexes. With DED, another dimeric species, Cu~2~L~2~H, is formed in addition. Independent numerical treatment of spectrophotometric and poteritiometric titrations was used to obtain a satisfactory model for the complexation and to test the relative discriminatory power of the two methods. Titrations of glycine ethylamide (GEA) were used as an additional test and as a model for DED and DPD. It was shown that in each case spectrophotometric titrations give results of similar reproducibility and have a discriminatory power equal to or better than potentiometric titrations, provided that optimum mathematical algorithms are used in the numerical treatment.