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The Stabilities and Thermodynamic Properties of Triethylenetetraminehexaacetic Acid Chelates of the Tripositive Lanthanide Ions
Author(s) -
Hseu TongMing,
Chang ChunChih,
Lin ZuiFeng
Publication year - 1987
Publication title -
journal of the chinese chemical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.329
H-Index - 45
eISSN - 2192-6549
pISSN - 0009-4536
DOI - 10.1002/jccs.198700028
Subject(s) - chemistry , chelation , lanthanide , stability constants of complexes , enthalpy , inorganic chemistry , ionic strength , ion , titration , metal ions in aqueous solution , analytical chemistry (journal) , thermodynamics , organic chemistry , physics , aqueous solution
Abstract The interaction between the decadentate ligand triethylenetetraminehexaacetic acid (TTHA or H 6 Z) and tripositive rare‐earth metal ions (Ln 3+ ) has been investigated. The acid formation constants of the hydrogen chelates (LnHZ 2− , LnH 2 Z‐) and the formation constants of the normal chelates (LnZ 3− ) have been evaluated at 15, 25 and 35° C , and at an ionic strength of 0.1 (KNO 3 ), the former by a titration method and the latter by a mercury indicator electrode technique. Enthalpy and entropy changes characterizing the formation of the normal chelates have been calculated at 25° C . These functions have been compared with corresponding values for related chelating agents.