Crystal structures of a copper(II) and the isotypic nickel(II) and palladium(II) complexes of the ligand (E)-1-[(2,4,6-tri­bromo­phen­yl)diazen­yl]naphthalen-2-ol

In the copper(II) complex, bis­{(E)-1-[(2,4,6-tri­bromo­phen­yl)diazen­yl]naph­thalen-2-olato}copper(II), [Cu(C16H8Br3N2O)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) A], 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(C16H8Br3N2O)2], (II), and bis­{(E)-1-[(2,4,6-tri­bromo­phen­yl)diazen­yl]naphthalen-2-olato}palladium(II), [Pd(C16H8Br3N2O)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. C71, 9–18]. The formula mass and unit-cell characteristics of the disordered solvent mol­ecules were not taken into account during refinement.