Theoretical studies on oxovanadium(IV) complexes with sterically crowded Schiff base ligands

Abstract

Abstract. Electronic structures of five oxovanadium(IV) complexes with sterically crowded Schiff base ligands are optimized by using density functional theory (DFT/B3LYP) method with LANL2DZ basis set. The studied complexes are [N,N'-ethylenebis(o-(tert-butyl- (4) and bis(N-methyl-o-(tert-butyl-p-methylsalicylaldiminato) oxovanadium (IV) (5). The structural parameters and stretching frequencies were obtained for five oxovanadium(IV) complexes. The calculated structural parameters show that the vanadium(IV) center is distorted square pyramidal (dsp) for complexes (1), (2) and distorted trigonal bipyramidal (dtbp) for complexes (3), (4) and (5). The excitation energies of complexes were obtained by using time-dependent density functional theory (TD-DFT/B3LYP) method with LANL2DZ basis set in dichloromethane solvent. The calculated excitation energies are in a good agreement with experimental datum for oxovanadium(IV) complexes. Frontier orbital energies (ELUMO and EHOMO), global hardness (), softness (σ) and LUMO-HOMO energy gap (E) were calculated to predict the antidiabetic effects of complexes. According to these quantum chemical parameters, antidiabetic effect ranking of the complexes were predicted as (1) > (2) > (5) > (3) > (4).

Electronic Structure, IR and UV-Vis Spectra of Some Suggested Ziegler-Natta Catalysts

“…The electronic properties were calculated according to Koopmans theorem [11,12]. Excitation energies and electronic transitions are carried out by using the Time Dependent TD density functional theory [12][13][14].…”