Title : Synthesis and structural Insights into monoethanolammonium bis(pyridine-2,6-dicarboxylato)nickelate(II)
Abstract:
2,6-pyridinedicarboxylic acid (H₂dipic) is a versatile N,O-chelating ligand that forms stable complexes through various coordination modes. This study focuses on the synthesis and structural characterization of a new mixed-ligand nickel(II) complex to explore its intermolecular interaction landscape.
Methods: The complex Ni(dipic)₂₂ was synthesized by reacting nickel(II) acetate with 2,6-PDCA and monoethanolamine (https://www.google.com/search?q=MEA) in a 1:2:2 molar ratio. The reaction was maintained at 60°C for 30 minutes with intensive stirring. Single crystals suitable for X-ray diffraction (XRD) were obtained via slow evaporation. Intermolecular interactions were quantified using Hirshfeld surface analysis via CrystalExplorer 17.5.
Results: X-ray structural analysis revealed that the Ni(II) center adopts a distorted octahedral geometry. The metal is coordinated by two tridentate dipic ligands, each binding through two carboxylate oxygen atoms and one pyridine nitrogen atom. The [Ni(dipic)₂]²⁻ anionic unit is balanced by two [NH₃CH₂CH₂OH]⁺ cations. Hirshfeld surface mapping ($d_{norm}$) highlights significant O...H/H...O (50.9%) and H...H (18.7%) interactions as the primary stabilizing forces in the crystal lattice. Strong hydrogen bonding was identified between the https://www.google.com/search?q=MEA hydroxyl/ammonium groups and the carboxylate oxygens of the dipic ligand.
Conclusion: The synthesis of the Ni(dipic)₂₂ complex was successfully achieved with an 86% yield. The structural data has been deposited in the Cambridge Crystallographic Data Centre (CCDC 2256725).
Keywords: 2,6-pyridinedicarboxylic acid, Nickel(II) acetate, Crystal Structure, Hirshfeld Surface.
