2-Chloro-5-(trifluoromethyl)aniline-Derived Schiff Base Palladium(II) Complexes: From Molecular Design to Acute Toxicity Assessment.

Four Schiff bases newly synthesized from 2-chloro-5-(trifluoromethyl)aniline served as ligands for the preparation of four palladium(II) complexes. Characterization of all compounds was performed using the following physicochemical techniques: elemental analysis, IR, UV-vis, 1H NMR, 13C NMR, mass spectrometry, thermal analysis, molar conductivity, and magnetic susceptibility. In addition, crystals of the ligands HL1-HL4 and the complexes 2 and 4 were obtained, enabling their structures to be confirmed by single-crystal X-ray diffraction. Crystallography showed that ligands form molecular crystals with one molecule per unit cell, except HL1, which contains two chemically identical molecules; HL1, HL2, and HL4 are centrosymmetric, and HL3 crystallizes as a pure enantiomer. Complex 4 is mononuclear, coordinated by two deprotonated ligands through an N2O2 donor set, while complex 2 is dinuclear, with each palladium(II) coordinated via an O3N set by one bidentate anionic ligand and two bidentate-bridging acetate anions. Phytotoxicity and animal toxicity were assessed using Triticum aestivum L. and Artemia franciscana Kellogg, respectively. Complexes were slightly more inhibitory than ligands on Triticum, but overall effects were weak, with root growth exceeding that of the negative control at all tested concentrations. Only complexes 2 and 4 exhibited dose-dependent toxicity in Artemia, with LC50 values of 389.8 and 48.7 µM.