No abstract

ABSTRACT:The structure and properties of the lanthanum and lutetium ␤-diketonates and mixed Ln(dik) 3 ligand complexes with o-phenantroline, Ln(dik) 3 Phen, are modeled by using the quantum mechanical/molecular mechanical (QM/MM) technique with the universal force fields (UFF) in the MM part. The set of parameters for UFF was adjusted to obtain the adequate modeling of the structures. The LnOO and Ln(dik) 3 OPhen bond energies were estimated by using the single-point calculations with Becke's three-parameter functional with Perdew-Wang correlational functional density functional theory. It is shown that the LnOO and Ln(dik) 3 OPhen bond energies are decreasing in the series from nonbulky ␤-diketonate ligands to their branched analogs. The introduction of the fluorinated substituents leads to substantial increase in bond energy. The natural bond orbital analysis was used for characterization of electronic structure of the complexes.

The formation of two metastable complexes (M=L ¼ 1=2 and 1=1) is shown for low temperature co-condensates of europium and samarium vapors with mesogenic ligand 4-penthyl-4 0 -cyanobiphenyl (5CB). The DFT-calculations based on hybrid B3LYP potential have been carried out to study the equilibrium structures of complexes. The model structures including one and two metal atoms with antiparallel disposition of ligand molecules are considered. The spectral shifts for ligand CNgroup stretching vibrations and the relative thermal stability of the complexes are discussed.

No abstract