Syntheses and crystal structures of two novel Cu(II) and Co(II) complexes with 3-methyl-4-(p-bromophenyl)-5-(2-pyridyl)-1,2,4-triazole

A new ligand, 3-methyl-4-(p-bromophenyl)-5-(2-pyridyl)-1,2,4-triazole (L) and its complexes, trans-[CuL₂(ClO₄)₂] (1) and cis-[CoL₂(H₂O)₂](ClO₄)₂·H₂O·CH₃OH (2), have been synthesized and characterized by UV, IR, electrospray ionization mass spectrum, elemental analyses, and single-crystal X-ray diffraction methods. In the structure, two L ligands are stabilized by intermolecular π···π interactions between the triazole rings. In the complexes, each L ligand adopts a chelating bidentate mode through N atom of pyridyl group and one N atom of the triazole. Both complexes have a similar distorted octahedral [MN₄O₂] core (M = Cu²⁺ and Co²⁺) with two ClO₄^- ions in the trans position in 1 but two H₂O molecules in the cis arrangement in 2.