Russian Journal of Inorganic Chemistry‎, ( ISI ), Volume (53), No (4), Year (2008-6) , Pages (660-664)

Title : ( Thermodynamic Behavior of Complexation of 18-Crown-6 with Tl+, Pb2+, ‎Hg2+, and Zn2+Metal Cationsin Methanol–Water Binary Media )

Authors: Glamhossein Ronagi , Mohammad Hossein Arbab Zavar , - - ,

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Abstract

The equilibrium constants and thermodynamic parameters for complex ‎formation of 18-Crown-6 (18C6) with Tl+,Pb2+,Hg2+, and Zn2+ metal cations have ‎been determined by conductivity measurements inmethanol (MeOH)–water (H2O) ‎binary solutions. 18-Crown-6 forms 1 : 1 complexes with Hg2+and Zn2+cations,but ‎in the case of Tl+and Pb2+cations, in addition to 1 : 1 stoichiometry, 1 :2 ‎‎(ML2)complexes are formedin some binary solvents. The thermodynamic parameters ‎‎( and ), which were obtained from the temperature edependences of equilibrium ‎constants, show that in most cases the complexes are enthalpy destabilized but ‎entropy stabilized. Non-linear behavior is observed between the equilibrium constants ‎‎( ) of complexes and the composition of the mixed solvent. The selectivity of the ‎ligand for these metal cations is sensitive to the solvent composition, and, in some ‎cases, the selectivity order is reversed in certain compositions of the mixed solvent. ‎The results also show that the mechanism of complexation reactions and the ‎stoichiometry of complexes of some metal cations change with the nature and even ‎with the composition of the mixed solvent.‎

Keywords

, 18-Crown-6 (18C6), Tl+, Pb2+, Hg 2+, and Zn2+ metal cations, methanol (MeOH)-water (H2O) binary solutions
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@article{paperid:1008297,
author = {Ronagi, Glamhossein and Arbab Zavar, Mohammad Hossein and -, -},
title = {Thermodynamic Behavior of Complexation of 18-Crown-6 with Tl+, Pb2+, ‎Hg2+, and Zn2+Metal Cationsin Methanol–Water Binary Media},
journal = {Russian Journal of Inorganic Chemistry‎},
year = {2008},
volume = {53},
number = {4},
month = {June},
issn = {0036-0236},
pages = {660--664},
numpages = {4},
keywords = {18-Crown-6 (18C6);Tl+; Pb2+; Hg 2+; and Zn2+ metal cations;methanol (MeOH)-water (H2O) binary solutions},
}

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%0 Journal Article
%T Thermodynamic Behavior of Complexation of 18-Crown-6 with Tl+, Pb2+, ‎Hg2+, and Zn2+Metal Cationsin Methanol–Water Binary Media
%A Ronagi, Glamhossein
%A Arbab Zavar, Mohammad Hossein
%A -, -
%J Russian Journal of Inorganic Chemistry‎
%@ 0036-0236
%D 2008

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