Structural, Physicochemical, and Biological Insights into Novel (Acetylacetonate)(Oxydiacetato)Oxidovanadium(IV) Complexes with N‐Containing Aromatic Compounds

The crystal structures of three novel oxidovanadium(IV) salts containing the [VO(acac)(oda)]^- anion (acac=acetylacetonate, oda=oxydiacetate) and quinolinium ([QH]⁺), isoquinolinium ([(isoQ)H⁺) and acridinium ([(acr)H⁺)] counterions, of molecular formulas [QH][VO(acac)(oda)] (1), [(isoQ)H][VO(acac)(oda)](H₂O) (2) and [(acr)H][VO(acac)(oda)](H₂O)₂ (3) are reported. Notably, these complexes represent the first structurally characterized salts comprising the heteroligand [VO(acac)(oda)]^- complex anion. A comprehensive physicochemical characterization of the complexes in both solid state and solution is provided, with general discussions on the role of nitrogen-containing heterocyclic compounds on the structure of the resulting ternary oxidovanadium(IV) complexes. The experimental results were complemented by density functional theory (DFT) calculations to evaluate possible ligand conformations in the coordination sphere of V(IV). In addition, the nature of the bonds involved in the chelation of the vanadium(IV) cation is considered and a detailed assessment of the electron spin density is presented. Finally, the cytotoxic activity of the compounds was tested against breast (MDA-MB-231 and MCF-7) cancer cell lines to assess their potential use as chemotherapeutic agents in cancer therapy.