Synthesis, crystal structure, Hirshfeld surface and void analysis of bis(μ2-4-aminobenzoato-κ2 O:O′)bis[bis(4-aminobenzoato-κ2 O,O′)diaquathulium(III)] dihydrate

Abstract

The asymmetric unit of the title compound, [Tm2(C7H6NO2)6(H2O)4]·2H2O, contains three 4-aminobenzoate (4ABA) ligands, two coordinated water molecules, a thulium metal ion, and a water molecule of crystallization. The overall structure of the complex (4ABA-Tm) is in the form of a dimer. In the dinuclear thulium complex, symmetry-relevant TmO8 coordination polyhedra are formed by the O atoms of two chelating 4-aminobenzoate ligands, the O atoms of two non-chelating 4-aminobenzoate ligands, and two water molecules. The Tm—O bond lengths range from 2.216 (3) to 2.471 (3) Å with the Tm...Tm separation in the dinuclear complex being 4.7863 (5) Å. The crystal structure features O—H...N, N—H...O, and O—H...O hydrogen-bonding interactions. Further stabilization of the crystal packing is due to C—H...π and off-set π–π stacking interactions. Hirshfeld surface analysis indicates that H...H contacts are the most significant contributors to the crystal packing (45.9%). In addition, a void analysis was performed to check the strength of the crystal packing.