Synthesis, characterization and DFT aspects of some oxovanadium(IV) and manganese(II) complexes involving dehydroacetic acid and β-diketones

Six new mixed-ligand oxovanadium(IV) and manganese(II) complexes of the general composition [VO(dhaH)(L¹H)(L²)] and [Mn(dhaH)(L¹H)(L²)], where dhaH=dehydroacetic acid, L¹H=β-ketoenolates viz., acetoacetanilide (aaaH), o-acetoacetotoluidide (o-aatdH), o-acetoacetanisidide (o-aansH) and L²=benzimidazole (bzl), 3-methyl-1phenyl-2pyrazoline-5one (mphp), 2-aminobenzimidazole (abzl) or 2-aminobenzathiozole (abtz) have been synthesized. The resultant complexes were characterized on the basis of elemental analysis, molar conductance, magnetic measurements, mass spectrometry, thermogravimetric analysis, infrared and electron spin resonance studies. The thermal decomposition processes of one representative of the complexes are discussed and the order of reaction (n), the activation energies (E_a), the pre-exponential factor (A), have been calculated from thermogravimetric (TG) and differential thermogravimetric (DTG) curves. Gaussian 09 software package was used to carry out theoretical computation using density functional theory (DFT) methods with Becke3-Lee-Yang-Parr (B3LYP) hybrid exchange-correlation functional and the standard LANL2 MB basis set. Based on combined experimental-theoretical characterization, a suitable octahedral structure has been proposed for this class of complexes.