Crystal structure and Hirshfeld-surface analysis of di-aqua-bis-(5-methyl-1 H -1,2,4-triazole-3-carboxyl-ato)copper(II).

The title compound, [Cu(H L ) 2 (H 2 O) 2 ] or [Cu(C 4 H 4 N 3 O 2 ) 2 (H 2 O) 2 ], is a mononuclear octa-hedral Cu II complex based on 5-methyl-1 H -1,2,4-triazole-3-carb-oxy-lic acid (H 2 L ). [Cu(H L ) 2 (H 2 O) 2 ] was synthesized by reaction of H 2 L with copper(II) nitrate hexa-hydrate (2:1 stoichiometric ratio) in water under ambient conditions to produce clear light-blue crystals. The central Cu atom exhibits an N 2 O 4 coordination environment in an elongated octa-hedral geometry provided by two bidentate H L - anions in the equatorial plane and two water mol-ecules in the axial positions. Hirshfeld surface analysis revealed that the most important contributions to the surface contacts are from H⋯O/O⋯H (33.1%), H⋯H (29.5%) and H⋯N/N⋯H (19.3%) inter-actions.