2-Chloro-4-fluorobenzoate vs. 2,4-dichlorobenzoate: A comparative study of non-covalent interactions in copper(II) 2-chloro-4-fluorobenzoate and copper(II) 2,4-dichlorobenzoate complexes with nitrogen-donor ligands

The coordination behavior of 2-chloro-4-fluorobenzoate and 2,4-dichlorobenzoate ligands towards copper(II) ion were investigated in the presence of different nitrogen ligands. Four new copper(II) complexes, [trans-Cu(2-Cl-4-FC7H3O2)(2)(beta-pic)(2)] 1, [trans-Cu(en)(2)(H2O)(2)](2-Cl-4-FC7H3O2)(2), 2, [trans-Cu(2, 4-Cl2C7H3O2)(2)(beta-pic)(2)(H2O)(2)], 3 and [trans-Cu(en)(2)(H2O)(2)](2,4-Cl2C7H3O2)(2).2H(2)O, 4, (where beta-pic = beta-picoline, en = ethylenediamine) were synthesized by addition of beta-picoline/ethylenediamine to the respective hydrated copper(II) arylcarboxylate suspended in methanol-water (4:1) mixture at room temperature. The newly synthesized complexes have been characterized by elemental analyses, TGA, spectroscopic techniques (FT-IR and UV-Vis), conductance, magnetic susceptibility studies. Single-crystal X-ray structure determination of the complexes revealed the presence of neutral structure in complexes 1 and 3 whereas complexes 2 and 4 possess ionic structure consisting of complex cation [trans-Cu (en)(2)(H2O)(2)](2+) and two 2-chloro-4-fluorobenzoate/2,4-dichlorobenzoate as counter anions. The crystal lattice in these copper(II) complexes is stabilized by various non-covalent interactions such as N-H...O, O-H...O hydrogen bonds and other weaker interactions including C-H... pi, C-H....halogen and halogen...halogen ones. A comparison of non-covalent interactions in four copper(II) complexes is also discussed.