Photoelectron spectra and electronic structure of Zn(II)bis-β-diketonates with aromatic substituents by the PES, DFT, and OVGF methods

The electronic structure of Zn(II) bis-beta-diketonate complexes was studied by the methods of ultraviolet photoelectron spectroscopy (PES) (HeI) and electron density functional theory (CAM-B3LYP/cc-pVTZ): acetylacetonate (Zn(acac)2), its thio-analogs with aromatic substituents in the beta positions – Zn(OC(OEt)CHC(C6H5)S)2 and Zn(OC(CH3)CHC(C10H7)S)2. To improvethe analysis of the spectra, the raw spectra were compared with differential spectra (second derivative), the spectra were interpreted using calculations in the outer valence Green functions (OVGF) method. In order to study the electronic effects at substitution of O by S and CH3 by С6Н5 in Zn(acac)2, the electronic structures of Zn(acac)2 and Zn(Sbzac)2 were calculated and analyzed. It is shown that in Zn(bzac)2 the dihedral angles between the planes of cycles of chelate and aromatic substituents are close to 40–45°, that allows π-σ mixing. The splitting of Zn3d-orbitals by ligand fieldinto a1+b1+b2 +e and their mixing with the ligand MOs, shown by the DFT method was used in the interpretation of the PES spectrum.