Synthesis and Characterization of V(IV), V(V), and Fe(II) Complexes with Bidentate Donor Ligands

Abstract

The overall goal of this thesis is to synthesize and characterization complexes of transition metal ions of the VO(II), V(V), and Fe(II) with bidentate ligands in various molar ratios, as well as their mixed-ligands complexes. Many types of spectroscopic methods including (FT-IR, UV-Vis, 1H-NMR, and GC-mass spectrometry) were used to determine these molecular geometry structures (melting point, molar conductivity, and magnetic susceptibility measurements). Thus, this work may be described as follows: The FT-IR spectra of the produced complexes revealed that all the ligands exhibited bidentate coordination by N-N, N-O, and O-O atom on both its ends with (VO(II), V(V), and Fe(II)). The magnetic susceptibility at 25 ⁰C shows that the VO(II) complexes are paramagnetic, whereas V(V) and Fe(II) are diamagnetic. When conducting molar conductivity studies of the VO(II), V(V), and Fe(II) complexes in H2O as a solvent, molar conductivity measurements demonstrate that certain complexes are an electrolyte and other complexes have ionic nature of type 1:1 and 1:2 electrolytes. A series of laboratory experiments yield data indicating that the complexes VO(II) are formed via complexes featuring square pyramidal organization of complex molecules while the V(V) and Fe(II) complexes are formed as complexes utilizing the octahedral formation of complex molecules. Theoretical calculations of the free ligands and some prepared complexes have been done by using DFT calculations with proper basis sets for each other. The complexes were very stable and their energies ranged from (-775.86 to -1164.09 a.u.) and were very different from that of the free (HQ, Ox, DTO and APy) ligands. The prepared complexes are more polar (5.69 to 15.54 Debye) than the free ligands. The HOMO orbitals energies of the complexes are ranged from (-0.098 to -0.392 a.u.), whereas the ligands are ranged from (-0.216 to -0.262 a.u.), and the LUMO orbitals energies of the oxocomplexes are ranged from (-0.007 to -0.296 a.u.).