Synthèse, caractérisation et étude des propriétés physico- chimiques de nouveaux complexes hétéroleptiques de Fer(III) à base du ligand oxalato(2-).

Abstract

Within the context of this thesis, two new heteroleptic organic-inorganic hybrid salts were synthesized and characterized by means of diverse experimental methods: These are (CH6N3)[K (H O) Fe (C O ) ] (1) 5242 2 4 6 et (CH6N3)2[Fe(C2O4)2(H2O)Cl] (2), (CH6N3)+ is guanidinium cation. Compound 1 crystallizes in a monoclinic system, space group centrosymetric P2 /c. Compound 2 crystallizes in an orthorhombic system, space group non- 1 centrosymetric Pbcn. Compounds 1 and 2 share guanidinium as a counter cation. Compound 1 consists of one guanidinium cation and one heteroheptanuclear complex anion, [K (H O) Fe (C O ) ] . In the 5242 2 46 - solid, this polymetallic anion forms a three dimensional polymer through oxalato bridges. The crystalline structure of 1 shows the cavities housing guanidinium cations. As for 2, it consists of two guanidinium cations and one mononuclear complex anion, [Fe(C O ) (H O)Cl] . The 2- 2 42 2 cohesion of the crystalline network in these compounds is reinforced by hydrogen bonds N–H···O and O–H···O in 1 and N–H···O, O–H···O and O–H···Cl in 2. The Hirshfeld surface analysis reveals that the hydrogen bonds O–H···O are most abundant with a contribution of 36.4 % (1) and 49.7 % (2). ATG thermograms confirm the absence of water of crystallization molecules in these compounds. The IR spectra confirm the presence of the guanidinium cation in both salts as well as that of oxalato(2-) ligands and aqua in 1; oxalato(2-), aqua and chlorido in 2. UV-Vis spectra show any visible-based absorption, which is characteristic of Fe ions in octahedral geometry in a low field. The spectra of EPR samples of compounds 1 and 2 measured at room temperature are substantially similar, the anisotropy of the g parameters along the two main axes complies with the complexes of Fe in an octahedral environment. The concordance of the different intensity peaks of the experimental and simulated spectra justifies the purity of the compounds 1 and 2. The two compounds exhibit antiferromagntic behavior at low temperatures. The evaluation of the in vitro antimicrobial activity revealed that compounds 1 and 2 are active on the strains of Klebsiella pneumoniae, Staphylococcus aureus, Candida albicans 358B when the diameters of the inhibitory zones are located between 15 mm and 20 mm.