trans-Dichloridobis(2,4-dimethylaniline-κN)palladium(II)

In the title compound, [PdCl2(C8H11N)2], the PdII atom is located on a crystallographic inversion center and adopts a square-planar coordination geometry, with pairs of equivalent ligands in trans positions. In the crystal, adjacent molecules are linked with each other through weak N—H⋯Cl hydrogen bonds and π–π stacking interactions between the phenyl rings [shortest centroid–centroid distance = 3.720 (2) Å], leading to the formation of layers parallel to the a-axis direction.

In the title compound, [PdCl 2 (C 8 H 11 N) 2 ], the Pd II atom is located on a crystallographic inversion center and adopts a square-planar coordination geometry, with pairs of equivalent ligands in trans positions. In the crystal, adjacent molecules are linked with each other through weak N-HÁ Á ÁCl hydrogen bonds andstacking interactions between the phenyl rings [shortest centroid-centroid distance = 3.720 (2) Å ], leading to the formation of layers parallel to the a-axis direction.
Data collection: APEX2 (Bruker, 2004); cell refinement: SAINT (Bruker, 2004); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: XP in SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXL97.  (Padmanabhan et al. 1985). Some dramatic results in homogeneous catalysis of reactions of organic compounds, particularly the successful commercial exploitation of the Wacker one stage process for the homogeneous catalytic oxidation of ethylene to acetaldehyde in the presence of palladium (II) chloride (Hartley 1973), have contributed to this interest. In this paper we report crystallization of the title compound, a new palladium(II) complex obtained by the reaction of 2,4-dimethylaniline with palladium chloride in ethanol. As illustrated in Fig.1, the Pd II atom exhibits a squareplanar coordination sphere, defined by two N atoms from two 2,4-dimethylaniline and two chloride atoms. The molecule adopts the trans configuration in the solid state. The bond distances of Pd-N (2.055 (2)) and Pd-Cl (2.293 (3) Å) are comparable with the values found in related complexes (Newkome et al. 1982;Chen et al. 2002). The dihedral angle between the plane of the phenyl ring and the square plane around Pd is 63.03 (1) °. In the crystal structure, intermolecular N-H···Cl hydrogen bonding interactions involving the amino groups and chlorine anions (Table 1) and π-π stacking interactions (centroid-centroid distance = 3.720 (2) Å) occurring between neighboring phenyl rings of centrosymmetrically related complexes form a layer network running parallel to the a axis (Fig. 2).

Experimental
A mixture of palladium chloride (0.1 mmol, 0.018 g) and 2,4-dimethylaniline (0.2 mmol, 0.024 g) in 12 ml of anhydrous ethanol was sealed in an autoclave equipped with a Teflon liner (25 ml) and then heated at 353 K for 1 day. Yellow crystals were obtained by slow evaporation of the solvent at room temperature (0.093 g, 45%). IR

Refinement
All H atoms were positioned geometrically and refined using a riding model with the distances of 0.97 Å for methyl groups with U iso (H) = 1.5U eq (C) and 0.94 Å for phenyl groups with U iso (H) = 1.2U eq (C), respectively. H atoms bonded to N atoms were placed at calculated positions and refined with distance constraints of N-H = 0.91 Å, and with U iso (H) = 1.2 U eq (N). The hightest residual electron density peak is located 0.93 Å from Pd1 and the deepest hole is located 0.95 Å from Pd1.

Figure 2
View of one of the two-dimensional layers of the title compound. The intermolecular hydrogen bonds and π-π stacking interactions are shown as turquiose and red dashed lines, respectively. H atoms not involved in hydrogen bonds have been omitted for clarity. where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max < 0.001 Δρ max = 1.65 e Å −3 Δρ min = −0.66 e Å −3

Special details
Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes. 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 R-factors(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.