Rare Earths-Schiff Base Complexes: A Potentiometric Study
T.K. Chondhekar
Department of Chemistry, Marathwada University, Aurangabad-431 004, India  

Stability constants of lanthanide chelates of Schiff bases derived from 5-chloro-2-hydroxy acetophenone and p-toluidine and m-toluidine have been determined at 25º, 35º and 50º ± 0.02ºC potentiometrically in 60% ethanol-water medium and 0.1 M (NaClO4) ionic strength. The lanthanides form 1 : 1 and 1 : 2 chelates and the trend in log K values show a break at gadolinium. Thermodynamic functions obtained revealed that the 1 : 1 chelates were enthalpy and entropy stabilized and 1 : 2 chelates showed predominance of entropy effect.


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  • Asian J. Chem. /
  •  1989 /
  •  1(2) /
  •  pp 178-180