Syntheses, crystal structures, Hirshfeld surface analyses, and magnetic property of a new dinuclear nickel(II) and two mononuclear copper(II) complexes with triaryltriazoles

A new dinuclear nickel(II) complex, [Ni₂(L¹)₂(H₂O)₄]Cl₄·6H₂O (1), and two mononuclear copper(II) complexes, [Cu(L¹)₂(H₂O)₂](NO₃)₂·2H₂O (2) and [Cu(L²)₂(H₂O)₂](NO₃)₂·2MeOH (3) (L¹ = 4-(p-methoxyphenyl)-3-(2-pyridyl)-5-(2-pyrimidinyl)-1,2,4-triazole, L² = 4-(p-methylphenyl)-3-(2-pyridyl)-5-(2-pyrimidinyl)-1,2,4-triazole), have been synthesized and characterized by elemental analysis, IR, PXRD, and single-crystal X-ray crystallography. The crystal structure analysis shows that the [Ni₂N₈] unit in 1 is almost planar, in which each Ni(II) ion is coordinated by four nitrogen atoms from L¹ equatorially and two water molecules axially in a distorted octahedral [NiN₄O₂] geometry. In complexes 2 and 3, the six-coordinated Cu(II) cation displays a distorted octahedral [CuN₄O₂] configuration. The intermolecular interactions in 1–3 have been investigated by 3D Hirshfeld surface analyses and 2D fingerprint plots to show that the prominent interactions are H···H and C···H/H···C contacts in 1, and H···H and N···H/H···N contacts in both 2 and 3. Furthermore, variable-temperature magnetic susceptibility of 1 indicates that there is a weak antiferromagnetic interaction between the two Ni(II) ions with J = −13.8(6) cm⁻¹.