Crystal structure of bis[(5-amino-1H-1,2,4-triazol-3-yl-κN4)acetato-κO]diaquanickel(II) dihydrate

Abstract

The title compound, [Ni(C4H5N4O2)2(H2O)2]·2H2O, represents the first transition metal complex of the novel chelating triazole ligand, 2-(5-amino-1H-1,2,4-triazol-3-yl)acetic acid (ATAA), to be structurally characterized. In the molecule of the title complex, the nickel(II) cation is located on an inversion centre and is coordinated by two water molecules in axial positions and two O and two N atoms from twotrans-oriented chelating anions of the deprotonatedATAAligand, forming a slightly distorted octahedron. Thetransangles of the octahedron are all 180° due to the inversion symmetry of the molecule. Thecis-angles are in the range 87.25 (8)–92.75 (8)°. The six-membered chelate ring adopts a slightly twisted boat conformation with puckering parametersQ= 0.542 (2) Å, Θ = 88.5 (2) and ϕ = 15.4 (3)°. The molecular conformation is stabilized by intramolecular N—H...O hydrogen bonds between the amino group and the chelating carboxylate O atom of twotrans-oriented ligands. In the crystal, the complex molecules and lattice water molecules are linked into a three-dimensional framework by an extensive network of N—H...O, O—H...O and O—H...N hydrogen bonds.