Role of non-covalent interactions in three copper(II) 5-chloro-2-nitrobenzoate complexes with N-donor ligands: Syntheses, characterization and packing analyses of trans-[Cu(β-pic)2(H2O)2(5-chloro-2-nitrobenzoate)2], trans-[Cu(γ-pic)2(5-chloro-2-nitrobenzo

•Three copper(II) complexes have been synthesized and characterized.•Single crystal X-ray crystallography revealed different modes of coordination.•EPR spectra exhibits exchange interactions.•Non-covalent interaction play crucial role in lattice stabilization.

Three new copper(II) complexes trans-[Cu(β-pic)2(H2O)2(5-chloro-2-nitrobenzoate)2] 1, trans-[Cu(γ-pic)2(5-chloro-2-nitrobenzoate)2], 2 and [trans-Cu(en)2(H2O)2](5-chloro-2-nitrobenzoate)2·2H2O, 3 (where β-pic = β-picoline, γ-pic = γ-picoline and en = ethylenediamine) were prepared by the addition of β-pic, γ-pic and en, respectively, to the hydrated copper(II) 5-chloro-2-nitrobenzoate, suspended in methanol–water mixture (4:1, v/v). The newly synthesized complexes have been characterized by elemental analyses, TGA, spectroscopic techniques (FT-IR, UV–Vis and EPR), conductivity measurements, magnetic susceptibility studies and single crystal X-ray structure determination. Complex 1 crystallizes in monoclinic crystal system with P21/c space group whereas the complexes 2 and 3 crystallizes in triclinic crystal system with P1¯ space group. Single crystal X-ray structure determination revealed the presence of elongated octahedral geometry in all three complexes. Cu(II) center is covalently coordinated by two 5-chloro-2-nitrobenzoate, two β-pic moieties and two water molecules in complex 1, two bidentate 5-chloro-2-nitrobenzoate and two γ-pic moieties in complex 2. In complex 3, the copper ion is coordinated to two chelating en ligands, two water molecules; with two 5-chloro-2-nitrobenzoate as counter anions and two water molecules of crystallization. The crystal lattice in complexes 1–3 is stabilized by an intricate network of hydrogen bonding interactions (C–H…O, O–H…O in complex 1, C–H…O in complex 2 and O–H…O, N–H…O and C–H…O in 3). Besides this, π…π stacking interactions in complex 1 and C–H…π interactions in complex 2 also contribute towards stability of the crystal lattice.

Graphical abstractThree new copper(II) complexes [Cu(β-pic)2(H2O)2(5-chloro-2-nitrobenzoate)2] 1, [Cu(γ-pic)2(5-chloro-2-nitrobenzoate)2] 2 and [Cu(en)2(H2O)2](5-chloro-2-nitrobenzoate)2·2H2O 3 have been synthesized, characterized by elemental analyses, TGA, spectroscopic techniques (IR, UV–Vis and EPR), conductance measurements, magnetic susceptibility studies and single crystal X-ray structure determination. The crystal lattice is stabilized by framework of supramolecular interactions (C–H…O, O–H…O, π…π stacking in 1, C–H…O, C–H…π in 2 and O–H…O, N–H…O and C–H…O in 3).Figure optionsDownload full-size imageDownload as PowerPoint slide