In the title copper(II) complex, the metal atom is coordinated by two N atoms and two O atoms from two bidentate ( E)-1-[(2,4,6-tribromophenyl)diazenyl]naphthalen-2-ol ligands, forming a slightly distorted square-planar environment. In the isotypic nickel(II) and palladium(II) complexes, the metal atoms are located on centres of inversion, hence the metal coordination spheres have perfect square-planar geometries.
In the copper(II) complex, bis{( E)-1-[(2,4,6-tribromophenyl)diazenyl]naphthalen-2-olato}copper(II), [Cu(C 16H 8Br 3N 2O) 2], (I), the metal cation is coordinated by two N atoms and two O atoms from two bidentate ( E)-1-[(2,4,6-tribromophenyl)diazenyl]naphthalen-2-olate ligands, forming a slightly distorted square-planar environment. In one of the ligands, the tribromobenzene ring is inclined to the naphthalene ring system by 37.4 (5)°, creating a weak intramolecular Cu⋯Br interaction [3.134 (2) Å], while in the other ligand, the tribromobenzene ring is inclined to the naphthalene ring system by 72.1 (6)°. In the isotypic nickel(II) and palladium(II) complexes, namely bis{( E)-1-[(2,4,6-tribromophenyl)diazenyl]naphthalen-2-olato}nickel(II), [Ni(C 16H 8Br 3N 2O) 2], (II), and bis{( E)-1-[(2,4,6-tribromophenyl)diazenyl]naphthalen-2-olato}palladium(II), [Pd(C 16H 8Br 3N 2O) 2], (III), respectively, the metal atoms are located on centres of inversion, hence the metal coordination spheres have perfect square-planar geometries. The tribromobenzene rings are inclined to the naphthalene ring systems by 80.79 (18)° in (II) and by 80.8 (3)° in (III). In the crystal of (I), molecules are linked by C—H⋯Br hydrogen bonds, forming chains along [010]. The chains are linked by C—H⋯π interactions, forming sheets parallel to (011). In the crystals of (II) and (III), molecules are linked by C—H⋯π interactions, forming slabs parallel to (10-1). For the copper(II) complex (I), a region of disordered electron density was corrected for using the SQUEEZE routine in PLATON [Spek (2015 ▸). Acta Cryst. C 71, 9–18]. The formula mass and unit-cell characteristics of the disordered solvent molecules were not taken into account during refinement.