(2,2'-Biquinoline-kappa(2)N,N')dichloropalladium(II), -copper(II) and -zinc(II).

In the three title complexes, namely (2,2'-biquinoline-kappa(2)N,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) degrees for (I), (II) and (III), respectively. The structure of (II) has twofold imposed symmetry.