الفهرس 
Introduction
SolutionsOnly 14 pages are availabe for public view
 |  | from | 398 |  |  |
| | | from | 398 | | |
Abstract
The results obtained can be summarized in the following points: 1- The proposed chemical formulae of the ligands and their metal complexes are in good agreement with the stoichiometries derived from their analytical data of carbon, hydrogen and metal contents. 2- All complexes have high melting points (> 300 °C) except [Cu(HPPS)Cl(H2O)2], [Cu(HAPO)Cl](H2O), [Hg(APO)2(H2O)2](H2O)2 and [Cd2(H2APO)Cl4(H2O)4] complexes and insoluble in most common organic solvents. 3- The coordination sites of the ligand, the nature of metal-ligand bonds, the existence of the solvated molecules were elucidated using IR spectra. Different modes of chelation for the investigated ligand were suggested based on careful comparison between the spectra of the ligands and those of their corresponding complexes. In general, three types of solid complexes were isolated in which the ligands may coordinate in neutral, mononegative and/or binegative manner. The ligands act as neutral bidentate via pyridyl nitrogen and thione sulphur (C=S) or neutral tetradentate via pyridyl nitrogen, thione sulphur, (NH)b and (NH)c or carbonyl oxygen group. Moreover, the ligands may act as mononegative bidentate via thiol (C-S) and pyridyl nitrogen or (NH)b. In addition, the ligands may act as mononegative tridentate through pyridyl nitrogen, thiol (C-S) and azomethine nitrogen or new azomethine nitrogen in case of H2PPS, via pyridyl nitrogen, thiol (C-S) and new azomethine nitrogen or (NH)b in case of H2PBO, via pyridyl nitrogen, enolic carbonyl oxygen group and new azomethine nitrogen or (NH)b in case of H2APO or via pyridyl nitrogen, (NH)b and thiol (C-S) in case of H2PPY. Also, H2PPS behaves as mononegative tetradentate via azomethine nitrogen, new azomethine nitrogen, (NH)a and thiol (C-S). In addition, H2PBO acts as binegative tridentate via new azomethine nitrogen, enolic carbonyl oxygen group and thiol (C-S). Moreover, the ligands may behave as binegative tetradentate via two thiol (C-S), azomethine nitrogen, new azomethine nitrogen, or pyridyl nitrogen in case of H2PPS, or via pyridyl nitrogen, two thiol (C-S) or one thione (C=S) , the second thiol (C-S) or thiol (C-S) and new azomethine nitrogen and carbonyl oxygen or enolic carbonyl oxygen group. Finally, H2PPY behaves as binegative pentadentate via two pyridyl nitrogen, two thiol (C-S) and new azomethine nitrogen. 4- The 1H NMR spectra of the diamagnetic Cd(II) and Hg(II) complexes were used to detect and confirm the potential coordination sites. 5- Detailed thermal analysis for the prepared complexes was performed in the temperature range 30-700 or 30-800 °C. The thermograms showed the decomposition steps after which a constant weight was observed corresponding to the remaining part of the complex after degradation. 6- The geometries were suggested for the prepared complexes based on the data evaluated from spectral and magnetic measurements: all Cr(III) and Hg(II) complexes assigned octahedral structure. All Cu(II) complexes assigned octahedral geometry except for [Cu(HAPO)Cl](H2O) complex, for which a square planar structure is proposed. For [Mn2(PPS)Cl2(H2O)4], [Mn2(H2APO)Cl4(H2O)4], [Co(PPS)(H2O)2](H2O), [Co(HAPO)Cl(H2O)2](H2O), [Ni(PPS)(H2O)2], [Ni(HAPO)Cl(H2O)2](H2O), [Cd2(PPS)Cl2(H2O)4] and [Cd2(H2APO)Cl4(H2O)4] complexes, an octahedral structure was suggested and a tetrahedral structure for [Mn(HPBO)Cl], [Mn(H2PPY)Cl2](H2O), [Co(PBO)(H2O)](H2O)2 and [Co(HPPY)Cl(H2O)](H2O) complexes. A square pyramidal geometry is suggested for [Cd2(PPS)Cl2(H2O)4] and [Cd(H2PPY)Cl2(H2O)] and mixed tetra- square plannar geometries for [Ni2(PBO)Cl2(H2O)2](H2O) and [Ni2(PPY)Cl2(H2O)](H2O) complexes. 7- Good information about the geometry and the degree of covalency of the metal-ligand bond for Cu2+ complexes were elucidated using ESR spectra. The spin Hamiltonian parameters of the complex were calculated. 8- In order to assess the influences of the structural properties of the ligands and the type of the metal on the thermal behavior of the complexes, the order n, and the heat of activation Ea of the various decomposition stages were determined from the TGA and DTG measurements using the coats-Redfern and Horowitz-Metzger methods. This section includes also the determination of the thermodynamic parameters of activation (ΔH*, ΔS* and ΔG*) which can be calculated by Eyring equation. 9- The ionization constants of H2PPS, H2PBO, H2APO and H2PPY and the stability constants of some complexes have been evaluated using pH-metric data at different temperatures. The acid-base character of the ligands is discussed based on its pH-metric titration with NaOH. The stability constants of the formed complexes have been evaluated using Irving-Rossotti model. In addition, thermodynamic parameters have been determined.