Complexation and thermodynamic studies of oxathiadibenzo crown ethers with some transition metals

Other Title(s)

دراسة الديناميكية الحرارية لمركبات الإيثر التاجية المحتوية على ذرات الكبريت و قدرتها على عمل معقدات مع بعض العناصر الإنتقالية

Dissertant

al-Biqain, Muhammad

Thesis advisor

Mizyid, Shihadah
al-Ashram, Muhammad Hasan

Comitee Members

al-Alaali, Abd Allah Muhammad
al-Rawashidah, Nadhir Ahmad
al-Suway, Muhammad Izzat

University

Mutah University

Faculty

Faculty of Science

Department

Department of Chemistry

University Country

Jordan

Degree

Master

Degree Date

2007

English Abstract

-A thermodynamic study of the complexation of Cu2+ and Pb2+ ions with 10, and the complexation of Cu2+, Pb2+, Zn2+ and Cd2+ ions with 11 in acetonitrile, has been carried out.

The study was conducted in the temperature range 283-308 K using a coductometric technique.

The observed molar conductivities, Λ, were found to decrease significantly for mole ratios [L]t/ [M]t less than unity.

A model involving 1:1 stoichiometry has been used to analyze the conductivity data.

The stability constant, K, for each 1:1 complex was determined from the conductivity data by using a nonlinear least squares curve fitting procedure.

The results show that compound 10 and 11 have no peak selectivity between Cu2+ and Pb2+, while the selectivity order of compound 11 is as follows: Cu2+ > Pb2+ > Zn2+ > Cd2+.

The values of standard enthalpy change (ΔH°) and entropy change (ΔS°) for complexation reactions were obtained from the slope and intercept of the van't Hoff plots respectively.

The standard Gibbs free energy change values (ΔG°) were determined from the Gibbs-helmholtz equation and the significance of these values is discussed.

The stability sequence of the complexes of 10 and 11 are as follows: 1- Pb2+ > Cu2+ for 10.

2- Pb2+ > Cu2+ > Zn2+ > Cd2+ for 11.

The spontaneity of the complexes is indicated by the values of ΔG°.

Also a conductance study of the interaction between AgNO3, Cu(ClO4)2, Hg(ClO4)2, Pb(ClO4)2, Zn(ClO4)2 and Cd(ClO4)2 with 10, 11 and 12 in acetonitrile-dimethylsulfoxide mixtures has been studied at 298K.

The results show that, the stability constants increased by increasing the DMSO percentage in the mixture.

This observation was discussed in terms of complexing agent that, the solvated metal ion form as a complexing agent which has two positive ends that are able to interact with the crown ether cavity.

The results also show the effect of the solvent on the stoichiometry of the complex, since the stoichiometry depends strongly on the nature of the medium

Main Subjects

Chemistry

Topics

• Electrical properties

No. of Pages

108

Table of Contents

• APA
• MLA
• AMA

Language

English

Data Type

Arab Theses

Record ID

BIM-304831