A study of the complexation of copper (II) ion by N-tetramethyl substituted diamines.

Abstract

The steric and ionic strength effects upon the chelating ability of substituted diamines with copper (II) ion was studied using N3N3N11N1-tetramethylethylenadiamine and N3N3N13N1-tetramethylpropylenediamine. The stepwise formation constants of copper (II) ion with the diamines were deteremined at 20 degrees, 30 degrees and 40 degrees C, and in aqueous .10-1OM C104 solutions. The Bjerrum potentiometric method was used to determine the constants. The results indicate a general decrease in stability with increasing chain length. The N-tetramethyl substituted dismines have been deteremined to be less stable than the substituted dismines. Also, the acid dissociation constants indicate that the N-tetramethyl substituted dismines to be less basic than the unsubstituted dismines. Thermodynamic parameters G, H4, and S were determined for k.