LAUSR

Abstract In this study, two new copper (II) carboxylate complexes, [Cu(4-mba)2(tmeda)](1) and [Cu(3-mba)2(H2O)2(tmeda)](2) (4-mbaH = 4-methylbenzoic acid, 3-mbaH = 3-methylbenzoic acid, tmeda = N,N,N',N'-tetramethylethyleneamine) were synthesized. The structures and properties of the complexes were determined by X-ray single crystal diffraction method and FT-IR spectroscopy. While the crystal packing of the complex 1 is stabilized by C—H•••O hydrogen bonds, in the complex 2, the molecules are connected to each other by C—H•••O and O—H•••O hydrogen bonds. The optimized structures were formed using density functional theory (DFT) at the B3LYP level within the 6–311G(d,p) and LAN2DZ basis sets. Their Hirshfeld surface analyses were performed for the detailed investigation of all the contacts involved in the crystal packing. 2D fingerprint plots and Hirshfeld surface analyses signify important interactions in the crystal packing [H⋯H (64.2%), C⋯H/H⋯C (21.1%) and O⋯H/H⋯O (14.7%) contacts for [Cu(4-mba)2(tmeda)], while [Cu(3-mba)2(H2O)2(tmeda)] showed H⋯H (67.3%), C⋯H/H⋯C (21.8%) and O⋯H/H⋯O (10.9%) contacts].