Dichlorido(4,7-diaza-1-azoniacyclononane-κ2 N 4,N 7)palladium(II) p-toluenesulfonate

The title compound, [PdCl2(C6H16N3)](C7H7SO3), consists of a PdII atom bonded to two N atoms of the 1,4,7-triazacyclononane (TACN) ligand and two chloride ions, which define a distorted square-planar geometry. The third N atom of the TACN ligand is protonated and hydrogen bonds to the p-toluenesulfonate anion. The Cl—Pd—Cl angle is larger than the N—Pd—N angle. The packing is dominated by layers, which are formed by the criss-crossing of two different hydrogen-bonded chains. One chain is composed of hydrogen-bonded Pd(TACNH)Cl2 + cations, while the second is formed through hydrogen bonding between the p-toluenesulfonate anion and the Pd(TACNH)Cl2 + cation.

The title compound, [PdCl 2 (C 6 H 16 N 3 )](C 7 H 7 SO 3 ), consists of a Pd II atom bonded to two N atoms of the 1,4,7-triazacyclononane (TACN) ligand and two chloride ions, which define a distorted square-planar geometry. The third N atom of the TACN ligand is protonated and hydrogen bonds to the ptoluenesulfonate anion. The Cl-Pd-Cl angle is larger than the N-Pd-N angle. The packing is dominated by layers, which are formed by the criss-crossing of two different hydrogen-bonded chains. One chain is composed of hydrogenbonded Pd(TACNH)Cl 2 + cations, while the second is formed through hydrogen bonding between the p-toluenesulfonate anion and the Pd(TACNH)Cl 2 + cation.

Comment
Complexes of Pd II and Pt II with 1,4,7,-triazacyclononane (TACN) have been reported in which the metal ion is coordinated to all three of the TACN nitrogen atoms  or to only two of the N atoms (Blake et al., 1988;Blake et al., 1993;Margulis & Zompa, 1992;Hunter et al., 1988). In the latter case, under acidic conditions, the non-Pd bonded N atom becomes protonated. As a result, hydrogen bonding networks can be formed in the presence of an acceptor site. A similar type of complex has been reported for Pt II (Davies et al., 2000).

Experimental
The ligand (TACN) was prepared according to the procedure reported in the literature (Kang & Jo, 2003). K 2 PdCl 4 (0.126 g, 0.387 mmol) was dissolved in deionized H 2 O (20 ml) and heated to 343 K. TACN (0.0500 g, 0.387 mmol) was dissolved in 50% 2-propanol/50% water solution (20 ml) and heated to 343 K. The two hot solutions were combined, removed from the heat and allowed to stir for 48 h. Yellow-brown crystals precipitated and were isolated by suction filtration. These were recrystallized from a 50% 2-propanol/50% water mixture to obtain crystals suitable for X-ray analysis.

Refinement
Carbon-bound H-atoms were placed in calculated positions(C-H 0.93 -0.97 Å) and were included in the refinement in the riding model approximation with U iso (H) set to 1.2-1.5 U eq (C). The nitrogen-bound H-atoms were located in a difference Fourier map and were refined with U iso (H) = 1.2U eq (N).

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