Synthesis, Spectral, X-Ray Diffraction, DFT, and Nematicidal Activity of Mixed Ligand Complexes of Ethyl 2-(2-Hydroxybenzylidine)-Hydrazine Carboxylate and 1,10-Phenanthroline with Some Transition Metals

In this work, mixed ligand complexes derived from ethyl 2-(2-hydroxybenzylidine)-hydrazine carboxylate (HL) and 1,10-phenanthroline (Phen) as ligands were synthesized and their structures elucidated by elemental analysis, infrared (IR), electronic,1H NMR, and mass spectra, X-ray diffraction (XRD), magnetic susceptibility measurements, and TG/DTG analyses. The analytical and spectral data support the formation of the complexes with the central ion in each complex six-coordinated and a slightly distorted octahedral geometry. The IR spectra showed that HL and Phen ligands act as neutral bidentates. The XRD patterns of the complexes showed their crystalline nature. The calculated bond length and the force constant F(U═O) in the uranyl complex are 1.738 A and 685.90 Nm−1, respectively. The molar conductance values of the synthetic complexes in DMF were found to be in the range 5.00–274.06 S cm2/mol at room temperature. The thermodynamic parameters were evaluated by using the Coats–Redfern (CR) and Horowitz–Metzeger (HM) methods. Theoretical molecular structures were investigated by the density functional theory/B3LYP method using the Gaussian 98 W basis set. The nematicidal activity of the ligands and its metal complexes was also studied.