trans-Dichloridobis(quinoline-κN)palladium(II)

In the title complex, [PdCl2(C9H7N)2], the PdII ion is four-coordinated in an essentially square-planar environment defined by two N atoms from two quinoline ligands and two Cl− anions. The Pd atom is located on an inversion centre, and thus the asymmetric unit contains one half of the complex; the PdN2Cl2 unit is exactly planar. The dihedral angle between the PdN2Cl2 unit and quinoline ligand is 85.63 (8)°. In the crystal, the complex molecules are stacked into columns along the b axis. In the columns, several intermolecular π–π interactions between the six-membered rings are present, the shortest ring centroid–centroid distance being 3.764 (3) Å between pyridine rings.

In the title complex, [PdCl 2 (C 9 H 7 N) 2 ], the Pd II ion is fourcoordinated in an essentially square-planar environment defined by two N atoms from two quinoline ligands and two Cl À anions. The Pd atom is located on an inversion centre, and thus the asymmetric unit contains one half of the complex; the PdN 2 Cl 2 unit is exactly planar. The dihedral angle between the PdN 2 Cl 2 unit and quinoline ligand is 85.63 (8) . In the crystal, the complex molecules are stacked into columns along the b axis. In the columns, several intermolecularinteractions between the six-membered rings are present, the shortest ring centroid-centroid distance being 3.764 (3) Å between pyridine rings.

Comment
In the title complex, [PdCl 2 (quinoline) 2 ], the Pd II ion is four-coordinated in an essentially square-planar environment by two N atoms from two quinoline ligands and two Clanions ( Fig. 1 and Table 1). The Cl atoms are in trans conformation with respect to each other. By contrast, in the analogous Pt II complex [PtCl 2 (quinoline) 2 ].0.25DMF (DMF = N,N-dimethylformamide), the Cl atoms are in cis conformation (Davies et al., 2001).
The Pd atom is located on an inversion centre, and thus the asymmetric unit contains one half of the complex; the PdN 2 Cl 2 unit is exactly planar. The nearly planar quinoline ligands, with a maximum deviation of 0.015 (4) Å from the least-squares plane, are parallel. The dihedral angle between the PdN 2 Cl 2 unit and quinoline ligand is 85.63 (8)°. The Cl atoms are almost perpendicular to the quinoline planes, with the bond angle <N1-Pd1-Cl1 = 89.53 (10)°. In the crystal, the complex molecules are stacked into columns along the b axis (Fig. 2). In the columns, several intermolecular π-π interactions between the six-membered rings are present, the shortest ring centroid-centroid distance being 3.764 (3) Å between pyridyl rings.

Experimental
To a solution of Na 2 PdCl 4 (0.2943 g, 1.000 mmol) in H 2 O (20 ml) was added quinoline (0.2590 g, 2.005 mmol). The mixture was stirred for 3 h at room temperature. The formed precipitate was separated by filtration, washed with H 2 O and EtOH, and dried at 50 °C, to give a yellow powder (0.3706 g). Crystals suitable for X-ray analysis were obtained by slow evaporation from its dimethyl sulfoxide (DMSO) solution at 90 °C.

Refinement
H atoms were positioned geometrically and allowed to ride on their respective parent atoms [C-H = 0.95 Å and U iso (H) = 1.2U eq (C)]. The highest peak (1.30 e Å -3 ) and the deepest hole (-0.40 e Å -3 ) in the final difference Fourier map were located 1.01 Å and 1.49 Å from the atoms Pd1 and H5, respectively. Fig. 1. A view of the molecular structure of the title complex, with displacement ellipsoids drawn at the 40% probability level and the atom numbering. Unlabelled atoms are related to the reference atoms by the (-x, 1 -y, -z) symmetry transformation.

trans-Dichloridobis(quinoline-κN)palladium(II)
Crystal data [PdCl 2 (C 9  Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > σ(F 2 ) is used only for calculating Rfactors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.