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 choice of different nitrogen-ligands influences the benzoate coordination behavior.
• The presence of water molecules are crucial in determining the packing modes.
• CH…halogen and halogen…halogen interactions play a role in stabilizing the supramolecular architectures.

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(β-pic)2] 1, [trans-Cu(en)2(H2O)2](2-Cl-4-FC7H3O2)2, 2, [trans-Cu(2,4-Cl2C7H3O2)2(β-pic)2(H2O)2], 3 and [trans-Cu(en)2(H2O)2](2,4-Cl2C7H3O2)2·2H2O, 4, (where β-pic = β-picoline, en = ethylenediamine) were synthesized by addition of β-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 NH…O, OH…O hydrogen bonds and other weaker interactions including CH…π, CH…halogen and halogen…halogen ones. A comparison of non-covalent interactions in four copper(II) complexes is also discussed.

Four copper(II) complexes, [trans-Cu(2-Cl-4-FC7H3O2)2(β-pic)2], [trans-Cu(en)2(H2O)2](2-Cl-4-FC7H3O2)2, [trans-Cu(2,4-Cl2C7H3O2)2(β-pic)2(H2O)2], and [trans-Cu(en)2(H2O)2](2,4-Cl2C7H3O2)2·2H2O, (where pic = picoline, en = ethylenediamine) were synthesized and characterized by different techniques. The coordination behavior of the benzoate ligands towards copper(II) ion were investigated in the presence of different nitrogen ligands; a comparison of non-covalent interactions in the four complexes was also presented.Figure optionsDownload as PowerPoint slide