Synthesis, crystal structure, Hirshfeld surface and void analysis of bis(μ2-4-aminobenzoato-κ2O:O′)bis[bis(4-aminobenzoato-κ2O:O′)diaquathulium(III)] dihydrate

The asymmetric unit of the title compound, [Tm-2(C7H6NO2)(6)(H2O)(4)]center dot 2H(2)O, 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) angstrom with the Tm center dot center dot center dot separation in the dinuclear complex being 4.7863 (5) angstrom. The crystal structure features O-H center dot center dot center dot N, N-H center dot center dot center dot O, and O-H center dot center dot center dot O hydrogen-bonding interactions. Further stabilization of the crystal packing is due to C-H center dot center dot center dot pi and off-set pi-pi stacking interactions. Hirshfeld surface analysis indicates that H center dot center dot center dot 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.