Two new isomeric copper(II) complexes: Syntheses, spectroscopic characterization, single crystal X-ray structure determination and packing analyses of [Cu(L1/L2)2 (TEMED)], where L1 = 4-chloro-2-nitrobenzoate, L2 = 5-chloro-2-nitrobenzoate and TEMED = N,N

Two new copper(II) complexes [Cu(L1)2(TEMED)] (1) and [Cu(L2)2(TEMED)] (2) (L1 = 4-chloro-2-nitrobenzoate, L2 = 5-chloro-2-nitrobenzoate, TEMED = N,N,N′,N′-tetramethylethylenediamine) have been obtained by the addition of TEMED to hydrated Cu(II) benzoates, in methanol–water (4:1, v/v) mixture. The newly synthesized complexes have been characterized by elemental analyses, spectroscopic techniques (UV–Vis, FT-IR, EPR), magnetic moment determination, thermogravimetric analyses, and single-crystal X-ray diffraction analysis. Both complexes 1 and 2 adopt monoclinic crystal structures (space group C2/c, Z = 4) and exhibit a distorted square planar coordination geometry around Cu(II) centers. Detailed packing analyses of complexes 1 and 2 have revealed that C–H⋯π interactions in complex 1 and C–Cl⋯π interactions in complex 2 stabilize the crystal lattice. In addition, the structures are influenced by weak C–H⋯O hydrogen bonding intermolecular interactions involving both nitro and carboxylate O atoms. EPR measurements showed the presence of different environment around Cu2+ in 1 and 2.

Graphical abstractTwo novel copper(II) complexes [Cu(L1)2(TEMED)] (1) and [Cu(L2)2(TEMED)] (2) (L1 = 4-chloro-2-nitrobenzoate, L2 = 5-chloro-2-nitrobenzoate, TEMED = N,N,N′,N′-tetramethyl ethylenediamine) have been synthesized, characterized by elemental analyses, TGA, spectroscopic techniques (IR, UV–Vis and EPR), magnetic susceptibility studies and single crystal X-ray structure determination. C–H…π interactions in complex 1 and C–Cl…π interactions in complex 2 provides robustness to the crystal lattice in both complexes. However, some significant C–H…O hydrogen bonding interactions have also been observed in both complexes.Figure optionsDownload full-size imageDownload as PowerPoint slide