(2,2′‐Biquinoline‐κ2N,N′)dichloropalladium(II), ‐copper(II) and ‐zinc(II)

In the three title complexes, namely (2,2′‐biquinoline‐κ²N,N′)dichloro­palladium(II), [PdCl₂(C₁₈H₁₂N₂)], (I), and the corresponding copper(II), [CuCl₂(C₁₈H₁₂N₂)], (II), and zinc(II) complexes, [ZnCl₂(C₁₈H₁₂N₂)], (III), each metal atom is four‐coordinate and bonded by two N atoms of a 2,2′‐biquinoline molecule and two Cl atoms. The Pd^II atom has a distorted cis‐square‐planar coordination geometry, whereas the Cu^II and Zn^II atoms both have a distorted tetra­hedral geometry. The dihedral angles between the N—M—N and Cl—M—Cl planes are 14.53 (13), 65.42 (15) and 85.19 (9)° for (I), (II) and (III), respectively. The structure of (II) has twofold imposed symmetry.